Carrier 38EV024320 User Manual

38EV,QV

HEATING A COOLING

Operation, Service and Troubleshooting

For Models 38EV024320, 38EV036320, 38QV024320, 38QV036320

CONTENTS
INTRODUCTION
Step 1 —General System Description

Step 2—Component Functional Description

• Outdoor Unit Components

• Indoor Unit Components

Step 3—Sequence Of Operation........................................ 7

Step 4—VVT-II Thermostat Operation Troubleshooting. 13
Step 5—System Troubleshooting

• Self-Diagnostics—Error Codes

• System Malfunctions—No Error Code

Step 6—Service and Maintenance....................................40

NOTE: Malfunction of certain electronic control compo

nents can cause lack of Automatic Emergency Heat initia
tion. See Service and Maintenance section for corrective
servicing procedures.

INTRODUCTION

This publication is designed to provide the information nec

essary to understand and troubleshoot Carrier’s 38EV and
s 38QV Variable Speed Split System Heat Pump and Air
' Conditioning Systems. The text covers variable speed 38EV

condensing and 38QV heat pump outdoor units, coupled

with 40QV Fan Coil or 28RD/RN Coil and 58SS Furnace
with blower accessory package. AU system combinations
are controUed in a similar manner utilizing the same elec
tronic components for both heat pump and cooling only sys
tems. System Diagrams are shown in Figs. 2 and 3.

This guide covers single zone applications only. For multi

ple zone instaUation, see proper supplemental manual.

STEP 1—Gênerai System Description
Outdoor Units:

The 38EV condensing and 38QV heat pump units are
derived from standard Carrier single-speed units. The con
trol box is slightly larger to aUow room for the induction

inverter and system microprocessor control board.
Although the unit is 208/230 VAC single phase, the inverter

supplies three-phase power at a wide r^ge of frequencies to
control the speed of the three-phase compressor. By varying

compressor speed, the system is able to control its output
within a range of about one-half to fuU rated capacity. The
outdoor fan motor is of standard single-phase, single-speed
design.

Indoor Units:

The 40QV Fan Coü provides variable indoor airflow control
for the system. This feature gives the system the capability
not only to vary its output capacity, but to control humid

ity levels throughout this capacity range.
The 58SSB Blower Accessory provides these same,features

when coupled with a 58SSB Furnace and 28RD/RN Furnace
Coil.

..............................

....................

.......................................

1

1

15

Variable Speed Systems

Thermostat:

The 38EV/QV system must be installed with a VVT-II ther
mostat Model MST-04 or MST-16 with software revision 6.7
or higher, available through your Carrier distributor.

General Operation:

The abflity of the system to control compressor and blower
speeds as described above allows it to adjust its output
capacity to match the varying load requirements of an

installation.
This type of operation results in less on-off cycling (ref. Fig.

1), quieter operation and improved temperature control at

modera:te and low load conditions.

Fig. 1—Variable Speed System Matches Load

STEP 2—Component Functional Description

CONTENTS

Page

38EV, QV Outdoor Units

Main Control Board...............................................................4

Compressor Inverter..............................................................4

Compressors
Outdoor Coil, Suction Thermistor (Tl, T2)

Outdoor Fan Motor/Capacitor
Outdoor Solenoid Expansion Valve (SEV)
High Pressure Switch (HPS)

Low Pressure Switch (EPS)....................................................7

Emergency Stop Switch (ESS)

Crankcase Heater and Switch (CH, CHS)...........................7

40QV Fan Coil, 58SSB Furnace Blower Accessory

Interface Board ....

Blower Controller...................................................................7

Blower Motor

Indoor Solenoid Valve (SEV) . .............................................

Indoor Coil Thermistor (T3)..................................................7

Figs. 2 and 3 shows layout of components in the variable

speed control system. This section will describe each compo
nent and discuss its function in attaining proper system
operation.

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...............................................................7

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6
7

7

7
7

4

6
6

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obiigations.

Book| 1 I 1 I 4 I 4 PC 101 Cataiog No. 533-895 Printed in U.S.A. FormSSEV, QV-1SM Pg 1 12-87 Replaces: New

Tab I3al5al2al5a

38EV Variable Speed Air Conditioning System

SERVICE VALVES

THERMOSTAT

FAN COIL

40QV024
40QV036

SERVICE VALVES,

SERVICE PORT

OUTDOOR FAN

OUTDOOR UNIT

38EV024
38EV036

&

inrininTlTnili

iMTrifrilTTnW

felinui

™eidemh

N>1

----

°

-----

U

GND , 1 0 208/230 V.A.C.

LOW PRESSURE SWITCH

Fig. 2—Simplified System Schematic

(shown with 40QV Fan Coil)

ESS SWITCH
(036 ONLY)

SUCTION THERMISTOR

A87260

Fig. 3—Simplified System Schematic

(shown with 40QV Fan Coil)

A87215

38EV, 38QV Outdoor Unît
Main Control Board:

The main control board is located in the front of the 38E V/

QV control box. It is fully visible and serviceable by simply
removing the control box cover, as shovm in Fig. 4. All wir
ing connections for components internal to the unit are at
the top of the board as shown in Fig. 5. Low voltage connec
tions are at thè white 17 pin connector, high voltage (O.D.
fan relay) at the two push on terminals in the upper left. All

connections to the indoor unit aré made through the 15 con
ductor Interface Cable connector located in lower left of the
board.

Thè main "control boárd receives information on system sta
tus from 5 devices (including WT-II thermostat) and uses

it to determine proper control for its 10 outputs. These I/O’s

are listed below: •

Inputs:

1) Thermistor (T2), Suction Line.

2) Thermistor (Tl), O.D. coil (between expansion device
and coil).

3) Thermistor (T3), I.D. coil (between expansion device
and coil).

4) Compressor Inverter (over-current alarm).

5) Thermostat (cool/heat, capacity demand, etc.)

Outputs:

1) Inverter (compressor) speed signal.

2) I.D. Blower Speed Signal (via interface board).

3) O.D. Solenoid Expansion Valve* (refrig, expansion con
trol, heat mode).

4) I.D. Solenoid Expansion Valve (refrig, expansion con
trol, cool model).

5) Main Contactor (inverter/compressor on-off control).

6) O.D. Fan (on-ofif control).

7) Reversing Valve* (on-off control).

8) Aux. Heat (electric or furnace heat on-ofif).

9) On-Board LED (on-off for diagnostics codes, etc.)

10) Thermostat (display of diagnostics codes, etc.)

*38QV Heat Pump Units Only

Compressor Inverter:
NOTE: The following text describes disassembly of the con

trol box for purposes of explaining inverter, coniponent func
tion only. Inverter components are not serviceable, and
shoüld not be removed from the control box.

Serviceable items include only the main control board, con

tactor and fan capacitor.

Failure of any other component requires replacement of the
entire control box. See instructions included with replace
ment control box for this procedure.

The inverter is made up of 6 components, all mounted in the
38EV/QV control box. , ~

With the main system control board and backpanel
removed (3-screws) the inverter board is clearly visible (See
Fig. 6). _ w,, /;

Removal of the inverter board allows a view of the rest of
the inverter components, which are pointed out in Fig. 7.

(Refer to Fig. 8) The inverter operates with 208-230VAC,

single-phase input power provided to the Diode Module (or
diode bridge). Here the AG power is converted to high volt
age DC (325V approx.).

The large (black) Smoothing Capacitor in upper right of the
control box is required to Smooth the DC voltage and is at
this 325 VDC potential.

SUB-BOARD it2

SUB-BOARD tn

SMOOTHING CAPACITOR

CONTACTOR

CONTROL BOX-TO-UNIT
CONNECTORS

FAN CAPACITOR

Fig. 4—Control Box, Cover Off

17 PIN DIAGNOSTIC
CONNECTOR LED

INTERFACE

CABLE
CONNECTOR &
RETAINER
LATCH

Fig. 5—Control Board

The DC power is then provided to the Power Modules (3) or
Power Transistors via a buss mounted across all 3 modules.

The power modules drive the 3-phase compressor when the
Inverter Board receives a signal from the main control
board requesting a certain compressor speed. The inverter
board switches each power module on-ofif into a signal simu
lating a single-phase signal. (See Fig. 9A). Each power mod
ule is switched in the same pattern, but 120-deg. out-of

phase from the other two modules, so the total output is in
3-phase form. (See Fig. 9C).

A87438

A87216

POWER

MODULES (3)

HEAT SINK

A87440

Fig. 6—Control Board Removed Fig. 7—Inverter Board Removed

38EV/QV COMPRESSOR INVERTER OPERATION

. - .

.... SERIAL ........................................................

........

- -

A87441

..........

ON (325VDC) —

OFF (OVDC) —

/

\

Fig. 9—Inverter Power Module Switching

VOLTAGE OUTPUT

(Average of ON-OFF

■ voltage)

o

A87443

A change in the speed signal from the main control board

causes thé inverter board to switch the power modules at a
different rate, thus changing the 3-phase output frequency,
and compressor speed. (Ref. Fig..9B),

In summary, the inverter takes a 230V, single-phase, 60 Hz.

frequency input and converts it'to high voltage DC. It then
converts it to 3-phase AC power at frequencies of 30-90 Hz.
to drive the 3-phase compressor at speeds of 1800 to 5400
RPM.

Although other inverter components (shown in Fig. 4) were
not needed in the above'functional description, they are still
necessary to maintain inverter integrity and reliability.
Sub-board #1 is used to suppress electrical noise caused by
power module switching to prevent interference with the
inverter microprocessor. It also contains 2'current loops so
the inverter can monitor its own current output. Sub-board
#2 is an under-voltage protector for the inverter bbardr

Compressors—are of a spedial design to operate reliably
over the 180Ô-540Ô RPM (30-90 Hz. frequency) speed range.
They are driven by a standard design 3-phase motor. ,

—38EV024, 38Qy024 Models—have a reciprocating 'com

pressor with internal PTC heater and internal overload
feature. It has specially hardened valves for high speed
operation, and special oil pump to retedn proper lubrica

tion at low speeds.

Its internal current and temperature sensitive overload
resets automaticaUy when internal compressor motor
temperature drops to a safe level (overloads may require

. .. up to 30 minutes to reset). When an internal overload is

suspected of being open, check by using an ohm-meter
or continuity tester. - -

..:...

■

The internal high Pressure Relief Valve opens at a pres
sure differential of approximately 450-f-50 psig
between suction (low side) and discharge (high side) to

. allow pressure equalization..
See Table 1 for proper oil charge.
—38EV036, 38QV036 Models—have a scroll compressor.

This type of compressor contains no valves, similar to a

rotary type. The “movable” vane osciQates in a cam fash-

ion to force refrigerant around from outer edge to the cen
ter discharge, while compressing it.

The scroll compressor contains no internal overload
devices. Instead, an emergency stop switch (ESS) is
mounted to the top of the compressor (see description
below).

It also requires no high' pressure relief valve. At exces
sive pressure the scroll vane is hfted from its seahng
surface, allowing high tolow'side bypass.

Table 1—Refrigerant and Oil Charge

Unit

Model

38EV024

38QV024 ;

38EV036 : 8.1

38QV036

Charge

R-22(lb)

, 8;5 Sontex2000

9.5

Oil

Type

Calumet RD-15 or

Sunisco 4GS 41/39

Oil Charge (oz)
New/Recharge

( , : 55/51

Thermistors:

Three thermistors are utilized by the main control board to
monitor refrigerant temperatures at locations shown in
Figs. 2, 3 and 10. The same model thermistor is used at all

three locations. Each is mounted in a %6” O.D. tube secured
to the refrigerant hne for improved accuracy and protection
of the device, and then heavily insulated (armaflex tube).

O.D. Fan Motor/Capacitor:

The totally enclosed fan motor is of standard 208-230
single-phase design for single-speed operation. Its related
capacitor, located in lower right of the control box, is also of
standard design.

Outdoor Solenoid Expansion Valve (SEV)—38QV Heat

Pumps Only.
This device is identical to that used at the indoor unit,

except for accurator piston size. Refer to Indoor Solenoid

Expansion Valve Description.

Fig. 10—Thermistor Locations

58SSB Furnace Blower Accessory—Includes the same
motor as the 40QV fan coil. Its controller and interface
board are 115 VAC versions of the fan coil components,
mounted as shown in Fig. 13.

Interface Board—serves three major functions in the

system.

Whenever gas or electric heat is energized, the interface
board takes over control of the blower from the outdoor
unit. It then forces the blower to high heating speed, which

is adjusted at the blower speed trimpot (ref. Fig. 14).
The board also contains the VVTTI thermostat power

supply.

Last of all, it acts as a connection point for input power, and

the control circuit between outdoor unit and indoor compo
nents (i.e., indoor SEV, thermistor, transformer, and blower
motor).

Blower Controller—serves a function similar to the outdoor
unit compressor inverter. It converts single-phase, 60 Hz.
power into a variable frequency output to control blower
motor speed. High and low motor speed settings are adjust
able at a 10-pin connector on the controller.

Blower Motor—is of unique design, containing a permanent
magnet rotor for superior eflBciency.

High Pressure Switch (HPS)—is provided for high pressure
protection of the system. It is located on the hquid line in
38EV units, and the discharge hne in 38QV units, (ref. Figs.
2 and 3). Its setting is 425 (+ -10) psig.

Low Pressure Switch (LPS)—is included to provide loss-of­charge protection.

(

In 38QV heat pumps the LPS is located in the hquid line
between the outdoor coil and outdoor SEV (ref. Fig. 3). Its
setting is 5 + (+ -3) psig and provides protection in the heat
ing mode.

In 38EV coohng units, the LPS is located in the suction line

between suction service valve and accumulator (ref. Fig. 2).
Its setting is 27 (4--5) psig.

Emergency Stop Switch /EiSSj—Is used only on 38ÉV036
and 38QV036 model units. It is mounted to the top of the
scroU compressor to provide over-temperature protection,

as the scroll has no internal overload. It is located in the
safety electrical circuit in series with LPS and HPS
switches. The ESS is set to open on temperature rise at
265 + -10 deg.F and reclose at 210 + -20 deg.F.

Crankcase Heater and Switch (CH,CHS)—is connected
across the input side of the line filter and operates continu

ously except above the setting of the crankcase heater
switch (70-deg.F) which is located on the liquid hne.

The purpose of the heater is to keep the crankcase warm
during the off cycle and thus prevent dilution of the oil with
refrigerant. This assures good lubrication and prevents loss
of oil from the crankcase during startup. To energize crank
case heater, turn the indoor thermostat to OFF position and

energize electrical disconnect to the outdoor unit. If the elec
trical disconnect switch to the outside unit has been off for
an extended period of time, the crankcase heater should
be always energized for 24 hours before starting the
compressor.

INDOOR UNIT COMPONENT DESCRIPTION

40QV Fan Coils—Are essentially standard Carrier indoor
units with motor replaced by the variable speed motor and
208-230 VAC controller and interface board (ref. Figs. 11
and 12.)

A CAUTION

An extremely hard or sharp blow to the casing or drop
ping the motor may affect motor operation due to mag
net damage.

Indoor SEV Assembly—Is provided with the 38EV or 38QV

outdoor unit. It must be mounted to indoor unit liquid con
nection during installation. The 38EV SEV assembly pro
vides two expansion orifices in parallel; a main orifice, which

is controlled by the solenoid, and a b3q)ass orifice (See

Fig. 15).

The b5qiass orifice is sized to meter refrigerant properly at
low compressor speeds with valve de-energized. At high
Compressor speed, the solenoid is energized, allowing paral

lel flow through a second, main orifice, sized properly for the

additional refrigerant flow needed. At intermediate com
pressor speeds, the solenoid is cycled on-off to control mid
range flow rates.

The 38QV heat pump valve functions in much the same
manner, except the fixed bypass orifice is replaced by a
standard accurator piston. This allows the capability for
non-expanded flow in the reverse direction needed in heat

pumps. This valve, with cutaway, is shown in Figs. 16
and 17. See Table 3 for piston sizes.

The SEV solenoids are energized by a 24 VDC coil, driven
directly by the main control board.

Indoor Coil Thermistor (T3)—Mounted to the SEV assem

bly, it is identical to the outdoor unit thermistors.

STEP 3—Sequence Of Operation

Startup—Once the system is properly installed or serviced,
there are two methods available to start the system and
check operation.

The first method is the “Run Test” function, which is
highly recommended for operational checkout after initial
installation or servicing. The Run Test automatically oper
ates the system in both the heat (including aux. heat) and
cool modes, thus eliminating the need to adjust the thermo

stat a number of times to force system into the desired oper
ating conditions. “Run test” operation is detailed below.

LOW-VOLTAGE

TERMINAL AREA i|

FAN DECK WIRING-^^
PASSAGE HOLE

(HIDDEN)

ACC ELECTRIC HEATER
AND CONTROLS

MOTOR LEADS

OUTDOOR CABLE
ENTRY HOLE

INTERFACE BOX

REFRIGERANT LINE
CONNECTIONS

SEV ASSEMBLY'

CONDENSATE
DRAINS

OUTDOOR CABLE
ENTRY HOLE

ECM MOTOR
CONTROLLER

BLOWER ASSEMBLY

INDOOR COIL

FILTER SECTION

A87445

Fig. 11—40QV024 Fan Coil

ACC. ELECTRIC
HEATER AND CONTROLS

jr LOW-VOLTAGE

TERMINAL AREA

1^'

MOTOR LEADS

ECM MOTOR
CONTROLLER

REFRIGERANT
LINE CONNECTIONS

SEV ASSEMBLY

CONDENSATE
DRAINS

FAN DECK WIRING
PASSAGE HOLE

INTERFACE BOX

BLOWER

ASSEMBLY

INDOOR COIL

FILTER SECTION

A87446

Fig. 12—40QV036 Fan Coil

R

ISOLATOR GROMMET

Fig. 13—58SSB Furnace Blower Assembly

A87447

INTERFACE CABLE
GROUND WIRE

SEV/THERMISTOR
CONNECTOR

INTERFACE CABLE

LOW VOLTAGE TERMINAL
BLOCK (TO ACCESSORT
HEATERS OR FURNACE)

THERMOSTAT
TERMINAL BLOCK

TO OUTDOOR
UNIT
LIQUID LINE

CONNECTOR FOR HEATER BOX TRANSFORMER
ACCESSORY OR FURNACE
BLOWER LEADS

„ PR1-2 POWER TO INTERFACE

LI, L2 POWER INPUT PRM,

Fig. 14—Interface Board

CONTROL POWER FROM
INTERFACE BOX
TRANSFORMER

A87448

THERMISTOR

Fig. 15—38EV SEV Cutaway

A87449

INDOOR
THERMISTOR

Fig. 16—38QV SEV Cutaway

A87450

Fig. 17—38QV SEV Parts

The second method involves setting the thermostat setpoint

for a high demand (4-deg.F or more from room temperature)
in the heat or cool mode. To accomplish this, refer to ther
mostat setup instructions, Step 4. This will allow the sys
tem to start and operate normally.

A “Speed-Up” function is available to aid in operational
checkout if the normal startup method is used. The “Speed-

Up” function shortens the delays and timing sequences of
the normal startup routine, and is described in this section.

The system Self-Diagnostic feature (Eef. Troubleshooting,
Step 5) is incorporated in both the Run Test and normal

startup operation.

Run Test-

Initiation—Remove the outdoor unit control box cover, then
apply power to indoor and outdoor units.

A WARNING

High Voltage power is supplied to control box compo
nents immediately upon closure of external main dis
connect. The main contactor is bypassed fqr initi^
charge-up of inverter capacitor (ref. Fig, 8). Electrical
shock or death may result,, ,,

one of the following responses:

a) The unit may not start (Error Codes 3-5,8).

b) The unit may shut down prematurely (Error Codes 9,

10). Compressor and/or indoor fan speed may fluctuate
before shutdown as the system attempts to verify or
clear the problem (Error Codes 11, 14).

c) The unit may complete the Run Test properly, but

flash an Error Code during operation. Some diagnos
tics, such as low cheu-ge indication (Error Code 15), are
designed to warn the serviceman of potential problems
but may not affect system operation.

Manual Checkout During Run Test:

Although the system is equipped with self-diagnostic capa
bilities, it should stül be visually and audibly inspected for

proper installation and operation during the Run Test.
A check list of system operational functions is included

below. Refer to Fig. 18 for the sequence of these functions
and check each item. To complete the list, the Run Test can

be initiated more than once.

a) Verify that compressor and outdoor fan operate with

out excessive vibration of the outdoor unit in its

mounted position.

b) Verify indoor blower operates in both the Cool and

Heat Mode.

c) Verify indoor solenoid expansion valve operates prop

erly by listening closely for valve clicking off-on at
about 3-second intervals.

d) Reversing valve switches off (detected by “woosh”

sound) when unit changes to Heat Mode. This sound
also ensures valve was properly energized for cooling
operation (38QV only). /

e) Verify that indoor blower speed override for gas or elec

tric heat operates properly (blower jumps from medium
to high speed). This function is necessary to guarantee

full blower speed operation when electric heat or fur
nace is on. (Blower control is different for gas vs. elec
tric heat as shown in Fig. 18).

f) Verify that electric heaters or furnace burners operate.

Once the “Run Test” has completed and the unit, including

auxiliary heat is off, the main control board LED will illumi
nate. When it extinguishes, system can be started normally
by adjusting thermostat.

The Red LED on Main Control Board will illuminate for
approximately 30 seconds, and then extinguish.

To initiate “Run Test” function, remove yellow jumper
(board is labeled “Run Test” as ishowri in Fig. 5). Unit will

start soon after jumper is reinstalled in its proper position
on the board. _ v

Operating Sequence;

In the absence of any diagnosed problems, the system will
operate in the Cool Mode for 7 minutes. It will then switch
to Heat with auxiliary heat on (gas or electric) and immedi

ately ramp the compressor down and off. Auxiliary heat
remains energized for about 3 minutes. See Fig. 18 for a pic
torial of Run Test sequence.

Influence of Diagnostics:

If a problem is diagnosed by the main control board, the
Red LED will flash an error code. Refer to Section 5, “Trou
bleshooting” for interpretation of the flashing code.

The system may, however, react in different ways, depend

ing upon the problem diagnosed. Certain errors wiU cause

A87452

Fig. 18—Run Test Sequence

(J

A WARNING

Unit is capable of restarting on normal thermostat
demand soon after Run Test is completed. Personal

injury can result.

Normal System Startup Sequence

Apply power to indoor units via main disconnect switches.

If outdoor unit control box cover is removed, main control
board LED wiU light and extinguish after 30 seconds.

Thermostat will display HPOO (for 38QV units) or ACOO (for

38EV units).

Set up thermostat in heat, cool or automatic mode for room
temperature desired (Ref. Thermostat Operation, Trouble
shooting Section 4).

Thermostat setpoint must be 2-deg.F or more away from
room temperature for the system to initiate a startup.
(Room temperature can be displayed on thermostat by
pressing both heat setpoint adjustment buttons to right of
display simultaneously).

Startup Sequence
NOTE: Startup delays and sequence times can be shortened

for system checkout by initiating “Speed-Up” jumper,
described below.

a) Time Guard-

Normal Ambient Startup—Mter applying power and/

or adjusting thermostat setpoint, the system will
undergo a 5-minute delay before starting. This will also
occur any time the system cycles off normally, to pre
vent unnecessary on-off cycling.

Low Ambient, Initial Startup—When outdoor tempera
tures are near or below 20-deg.F, the system will
undergo a 26-minute delay bn initial power-up only.
This allows the crankcase heater to at least partially
warm up compressor before startup.

Siartop—Compressor wffl start and ramp up to low

speed, outdoor fan wffl come on. Indoor blower will
start in a similar manner to compressor, 30 seconds
later.

b) Low Speed LocA-Iti—After starting, the' unit will lock

in at low speed for a period of 8 minutes. This is done
for the following reasons:

1. System self-diagnostics wffl monitor system condi-

tionis during this period to verify proper system
operation.

2. Allows indoor blower time to circulate and slowly

mix possibly cold ductwork air with room air, thus
avoiding erratic speed fluctuations due to unstable
thermostat readings.

c) Transition to Normal Control—li the thermostat is sat

isfied during the Srminute period at low speed, the sys
tem wffl remain at low speed for 4 more minutes and
then shut down. If not, it wffl speed up depending upon
thermostat demand. The startup sequence is complete.

“Speed-Up” Function

The “Speed-Up" jumper is a yellow jumper, similar to the

“Run Test” jumper. It’s located on the outdoor unit main
control board next to the label “Speed-Up” (ref. Fig. 5). The
function is initiated by removing and reinstalling the

jumper during the sequence period you want to eliminate.

For instance, if you want to ehminate the time guard period

before startup, wait for the LED to extinguish after power­up. Then pull and reinstall the “Speed-Up” jumper. This
wffl shorten the respective period, (i.e., 5 minutes down to 2

minutes for the normal time guard, or 20 minutes down to 4

minutes for low ambient initial startup).
If the jumper is pulled and reinstalled during a sequence

period listed in Table 2, it wffl shorten that period as indi

cated. The speed-up function will then cancel automatically
when the next event listed in the table occurs. To shorten
subsequent sequence periods, the jumper must be initiated
again.

Table 2—Speed-Up Function

Initiate The
Jumper During
This Period

—Prestart

Time Guard

—Low Speed

Lock in At
Startup

— Between Defrost

Periods (Beiow
32-Deg.F

Ambient)

—During Defrost 4-10 Min.-

*Low Ambient Initial Startup

Period Wiil
Shorten From
Normal- to Speed-Up

5 Min.—2 min.
OR* 20 Min.—4 Min.

8 Min.—
40-50 Seconds

45 Min.—4-5 Min.
(1st Defrost)

30 Min.-4 Mrs.­3-24 Min.
(Subsequent
Defrosts)

24 Sec-1 Min.

Speed-Up Function
Will Cancel
When

Compressor Starts

Compressor Begins
Ramping Above
Low Speed, Or
Shuts Down

Unit Initiates
A Defrost

Defrost Termination

Cooling Operation
Compressor—

During normal operation, the compressor speed will vary,
based on thermostat demand, from 2200 RPM at low speed
to 5000 RPM at high speed.

Indoor Blower-

Blower speed (or airflow) wffl “track” or follow compressor

speed; i.e., when the compressor is at low speed, so is the
blower. If the compressor ramps^oTiigh.speed, the blower
ramps to high speed simultaneously. This speed signal is
sent from the outdoor unit main control board, through the
indoor unit interface board to the blower controller. (See
Fig. 19).

Outdoor Fan—

The outdoor fan cycles on-off with the compressor.

Solenoid Expansion Valves (SEV)—

In the cooling mode only, the SEV at the indoor unit is oper
ated. SEV operation “tracks” or follows compressor speed
directly. At low compressor speed operation, the solenoid
remains off and aU refrigerant flow is directed through a
bypass orifice in the valve body (38EV systems). In 38QV
systems, the bypass orifice is located in the accurator piston
(Ref. Component Description, Section 3). At high compres-

sor speed, the solenoid is energized on continuously, allow
ing the extra refrigerant flow required through a second ori­flce in parallel to the bypass orifice. At intermediate com

pressor speeds, the SEV is cycled on-off at different rates,

depending upon compressor speed. This rate is based on a
5-secpnd on-off period, with the on-time increasing (with

compressor speed) from zero (at low speed) to the full five
seconds on (i.e., continuous on) at high speed. For instance,
at lower speeds, the SEV is on 1 second, off 4 seconds; at

medium speed, on 2.5 seconds, off 2.5 seconds, and so on.
Proper vsllve operation can be checked by listening closely

for the “clicking’’ at the indoor SEV during intermediate
speed operation. - --—

The system will cycle on-off at low speeds at moderate^ (75-

deg.F) outdoor temperatures. It will operate continuously at
increasingly higher speeds as outdoor temperatures
increase.

Heating Operation—38QV Systems Heat Pump

Heat pump operation is executed in the same manner as in
the coohng mode. Indoor blower speed and SEV control
“track” or follow compressor speed directly. However, in

the heat mode, only the outdoor unit SEV is operated. It is
cycled in the same pattern as cool mode control, except
cycling on-time is shortened at colder ambients, (i.e. At low
ambients, the SEV may also be cycling on-off rather than

remaining full on when the unit is at high speed).
The system will cycle on-off at low speeds during normal

operation at moderate (50-deg.F) outdoor temperatures. It
will operate continuously at increasingly higher speeds as
outdoor temperatures drop.

When outdoor temperatures drop to a point where supple
mentary heat is required, dr the optimizer function is ena
bled, electric or gas heat is initiated. Electric heat and

furnace operation are described in the following sections.

Table 3—38QV Piston Sizes

UNIT

38QV024

, - -•

38QV036 ,

Electric Heat Control—(38EV and 38QV ¡Systems)

Electric heat is initiated and controlled by energizing “W”
in the same manner as in standard systems. However, since
the variable speed blower heeds a speed input signal to oper
ate, blower control is considerably different.

Blower Control—In.=a standard 'heat package, energising
‘‘W)’’ energizes the heater sequencer(s). When this is done,

the ian relay is b3^assed-by 230V power to drive the blower
directly. Therefore, if the fan relay is faulty, the blower still
operates for safe electric heat operation.

40QV Fan Coil Units operate in a similar manner (Ref. Wir

ing Diagrams). However, instead of operating the blower

directly, this ■'230VAC power is apphed to the interface
board at terminals C and 1 (see Figs. 14 and 19). When these
terhiinals are energized by the electric heat sequencer, the

interface board relay breaks the speed signal connection
from the outdoor unit and allows the interface board to
drive the board at a speed set by the adjustable pot on the
board. ; '

LOCATION

Outdoor

. . '„ Outdoor ,,

Indoor

. Indoor

...............

. 52

-----

■ PISTON#
42

49

63

When the electric heat (“W”) is cycled off, normal sequencer

operation retains blower control from the interface board
until the heaters cool down. When terminals C and 1 are de
energized by heater package, blower control reverts back to
the outdoor main control board.

Supplemental (2nd Stage) Heat—(38QV Heat Pump/40QV

Fan Coil Systems Only)

Supplemental heat is required when the outdoor tempera
ture drops too low for the heat pump to handle the load

alone. At this point, the system begins cycling electric heat,
in addition to continuing full speed heat pump operation.
This is done by energizing heater package terminal “W.”
The heaters and blowers are controlled as described above.

A change in blower speed when the interface board takes
over control may not be noticeable, since the outdoor unit is
already operating it at high speed.

It may be noticeable if the blower heating speed trimpot is
adjusted below its maximum setting.

Heating Operation—(38EV Cooling Systems) and
Emergency Heat—(38QV Heat Pump Systems)

Electric or gas heat is operated directly on thermostat
demand on 38EV systems or whenever the 38QV outdoor
unit operation is locked out due to a diagnostic problem.
The blower is controlled by the interface board as described
above. However, since the blower is not being operated by
the outdoor unit during electric heat off cycles, the blower

will cycle fuU-on-off similar to standard systems.

NOTE: Malfunction of certain electronic control compo

nents can cause lack of Automatic Emergency Heat initia
tion. See Service & Maintenance section for corrective

servicing procedures.

The 58SSB furnace will operate as described in the litera
ture provided with it. The only difference is control of the
variable speed blower. The standard 58SSB furnace
bypasses its fan relay to lock-in blower operation when the
burner is on, just like an electric heat package.

The variable speed blower package switches blower control
to its interface board when “W” is energized, in the same

manner as described above for “Electric Heat Control.”

(The furnace interface board design is identical to that for

the 40QV fan coil, except it is a il5VAC yersioh)/
The blower will remain off for 2r3 minutes while the burner

ignites and warms the heat exchanger. The blower wUl then

start, and ramp to low speed for a short period before going
to full speed. 'When “W” is de-energized, the blower will
stay on for a short period to use the remaining heat from
theexchanger.

Supplemental (2nd Stage) and Optimizer Control—(38QV

Heat Pump/58SSB Furnace Systems)

Unlike fan coil operation, the furnace wiU not operate simul

taneously with the heat pump. Therefore, whenever the out

door temperature drops to where the heat pump cem no
longer match the load, or the optimizer setpoint is reached,
the heat pump wfll shut down when. furnace startup is
requested (“W” is energized). At this point, the heat pump
wfll also shut down the indoor blower (except if ,the thermo
stat is in the fan-on position). The normal furnace delay of
2-3 minutes wfll then pass before the blower is cycled back

on, to allow the heat exchanger to heat up. Once the thermo

stat is satisfied by the furnace, it will cycle off. Operation
wfll alternate between furnace and heat pump, until either
the heat pump can handle the entire load, or the optimizer
setpoint is reached. If the optimizer setpoint is reached, the

heat pump wfll be locked out (a minimum of two hours) and
the furnace will cycle directly on thermostat demand.

I

Adaptive Defrost—

38QV Heat Pump Systems utilize an adaptive defrost con
trol which clears the coil of frost only when necessary.

•r ■■

Based on coil conditions and outdoor temperature, the time
between defrosts is adjusted between 30 minutes and four

hours, as described below.

Between Defrost Period Calculation-

Defrost monitoring is begun when the O.D. coil thermistor
temperature drops below 32 degrees F. The first defrost will
occur 45 minutes later.

When the unit is ready to defrost, the pre-defrost O.D. coil
thermistor temperature (frosted coU) is memorized, and thè

unit then switches to defrost. A short time after defrost is
completed, a post-defrost thermistor temperature (clear coU)
is memorized.

The after-defrost (clear cod) temperature is used to estimate
outdoor temperature and the optimum pre-to-post defrost
coil temperature change (i.e. frosted coil vs. clear coU
temperature).

The time period to the next defrost is then determined by:

a) If defrost time was less than 5 minutes, add 30 minutes

to previous period.

b) If defrost time was maximum (10 minutes), and O.D.

con temperature at termination was:

—more than 45 degrees F, divide previous period in

half.

—less than 45 degrees F, next period will be 30 min

utes.

c) If defrost time was greater than five and less than 10

minutes, the new time is calculated by:

. . , optimum temperature change *

previous peno x actual post-defr. temp..minus pre-defrost temp.

*The new period calculated by this method cannot be less

than half, or more than double the previous period.

Other Limitations:

Maximum period between defrosts is 4 hours.
Minimum period between defrosts is 30 minutes, except:

The initial defirost after coming out of optimizer mode will
occur 15 minutes after startup.

Defrost Sequence—

When a defrost is initiated, compressor speed is dropped to
medium speed. This is done to mininiize shock to the com
pressor. The reversing valve and heat (terminal “W”) relays
are energized, the outdoor fan relay de-energized, and com
pressor then ramped to full speed for a rapid defrost.
Defrost is terminated on any of the following occurrences:

a) O.D. coil thermistor rises to 80 degrees F (when out

door temperature is above 10 degrees F).

b) O.D. coil thermistor rises to 60 degrees F (when out

door temperature is below 10 degrees F).

c) 10-Miuute maximum defrost period.

The system then ramps down to medium speed, returns to
heat mode, and returns to the pre-defrost speed.

Heat/Cool/Auto Control-

This thermostat function controls as in standard systems.
Heat or cool operation may be requested separately. The

“Auto” position allows the' system to switch between these
two modes automatically as required to satisfy thermostat
setpoint demand.

Fan-On/Auto-

With the fan-auto mode selected, the indoor blower will

•HP’OBQV)

\ / \ / \ /

•AC’(38EV).

■HP
00

z' \

NORMAL POWER-UP IMPROPER

Fig. 20-VVT-ll MST Thermostat

--------------------------------------

It

—1

65 HP

56 ;; 56

CONFIGURATION

/

---------------

1 lO'O oii—

^OWER HEAT

SETPOINT

COOL

N

ON I OFF I

68 69 70 71 72 76 77 78 79

4 ’HP' or 'AC:.

\

•66 HP

-HEAT

' \

SETPOINT

ROOM TEMPERATURE

05

SYSTEM
DIAGNOSTIC
ERROR CODE

A87454

cycle on-ofil with the outdoor unit and/or the electric/gas

indoor unit.
The fan-on mode will keep the indoor blower operating at all

times. The blower will operate at low speed during system­off intervals.

STEP 4 VVT-II Thermostat Startup/Troubleshooting

The MST-04 or MST-16 thermostat consists of a printed cir

cuit board, a connector board, and a wall mounted case.
A thermostat software revision of 6.7 or higher is required.
AU wiring connections to the thermostat are made to the

connector board. .
Mount the thermostat as described in 38EV or 38QV out

door unit installation instructions, or follow the Installation
Instructions included with each control. Thermostat must
be wired as shown in Figs.. 36 and 37.

Fig. 20 shows front view of the VVT-II MST thermostat.

Start-Up Procedure:

Close indoor main disconnect.

Normal Display—The thermostat will. display HPOO (for
38QV systems), ACOO (for 38EV systems), or 4 zeros, then
switch to the normal heating/cooiing setpoint as shown.

Blinking Display—If the thermostat display blinks on .and
off or is erratic, it is an indication that a wiring connection

is not correct, or that the thermostat is not receiving ade

quate power. Check the wiring connections and the supply

voltage (22VAC rninimum) at terminals SEC-1 and SEC-2

on the interface board. Make certain the thermostat ribbon

cable has been inserted into the connector board correctly.

Display Four Zeros—If the display shows four zeros upon
power-up, and then displays “HF-11,” it indicates that the
thermostat is currently configured for a multiple-zone sys
tem. It must be reset for single-zone control.

Setting Thermostat For Single-Zone Control—

To correct the configuration, set the rotary switch to posi
tion #1 (ref. Fig. 20). A number and “ON” or “OFF” will

V /

N

appear on the display. Press either of the right (“Heat”)
setpoint buttons to change the display to “OFF.” This is
the indication that the thermostat is now correctly set for
single-zone control. Now adjust the displayed number to
“2” by pressing the cool setpoint buttons; the lower one to

decrease the number, upper one to increase. Return the
rotary switch to position #0 and press any setpoint button
to display the normal setpoints.

Adjust Heating/Cooling Setpoints—The setpoints for both

heating and coohng can be easily adjusted by pressing the
setpoint buttons as shown.

Installer Adjustable_Fe Clock Option—Each
thermostat is equipped with a buüt-in instruction manual
which explains the various installer adjustable features and
how to set the time clock.

FoUow each page of the manual to configure the thermostat
based on the application. Always set the “Local Set-back
Control” to ON.

For single-zone control applications, the following features
wül have no effect on the thermostat operation and can be
disregarded at the time of installation:

#6—Duct Temperature Sensor Calibration
#7—Max Damper Position/Min Ventilation Position

#C—System Demand
#D—Communication Test ­#E—Supplemental Heat

Error Codes—3ie displayed as HF, SF, HP or AC followed
by a two digit number (ref. Fig. 20.) An HF or SF code
indicates a thermostat malfunction (see Thermostat Trou
bleshooting, below). A HP or AC code indicates a system
diagnostic malfunction (see System Troubleshooting,
Section 5).

Set-Back Feature—li the homeowner desires to use the set
back feature, remove the “set-back override jumper” from
the connector board at the back of the thermostat.

Operation—When an “OFF” time occurs, the thermostat
displays the word “SETBACK” and the highest cooRng and
lowest heating setpoints. When an “ON” time occurs the
thermostat returns to the last setpoints that were displayed

before set-back.

Overriding Set-Back—During set-back the heating'or cool
ing set-back Setpoint can be manually 'overridden by adjust

ing the setpoint through the use of the setpoint buttons.
The setpoint selected becomes the new comfort setpoint
that the thermostat uses when the next “OÑ” time occurs.

When the set-back setpdiiit is overridden the comfort

setpoint chosen remains displayed until the next “OFF”
time occurs; unless the' user manually adjusts the setpoint
back to the set-back setpoint; ;

Programming Set-Back—Follow the built-in thermostat

instruction mandai (behind front cover) to program the ON/

OFF times for set-back operation (and for programming the

electronic time clock). ■ , - .
Set-Back Programming Tips—If it is desirable for a particu

lar period to be in set back coiitinuóuály do not enter any

ON/OFF times for that period;

If it is desirable, for a particular period to be in the comfort
rnode continuoúsíy enter an ON time that is the same as an
OFF time.

Heating/Cooling Cycles—The thermostat should be set to
energize a heating cycle and a cooling cycle. Check to make
certain the 38EV or 38QV system operates properly.

“HEAT,” “COOL,” or “FAN” may be shown in the lower
left corner of the thermostat display depending on the sta
tus of the system. The 38EV or 38QV system controls to

1.5-deg.F from setpoint in both heat and cool modes. It will
start-up at 1.5 deg.F from setpoint (minimum run time is 12
minutes), and cycle off based on rate of room temperature
change (ref. Fig. 20).

VVI-ll Thermostat Troubleshooting

Hardware Failures—HF-11 or HF-12. The thermostat is not
properly configured for single-zone control application.
Make certain that “OFF” is displayed when the rotary
switcMs set to position #1.

HF-14, HF-15, or HF-16. There is a failure in the electronic
circuitry on the thermostat. Replace the thermostat circuit

board.
HF-13. The thermostat room temperature sensor is reading

out of its normal range ... 30 to 180 F. (Ref. thermostat

instructions).
Check the room temperature sensor to make sure that it is

physically intact.
Attempt to calibrate the room temperature sensor by fol

lowing the built-in instruction manual. If cahbration is not
possible, replace the thermostat circuit board.

Storage Failures—The thermostat continuously checks its
memory to make certain that stored information is valid. If

information is ever determined to be invalid an error code of

“SF” followed by a number is displayed.

When an “SF” error is displayed, the thermostat will also
use a safe, substitute value appropriate to the particular
code. (See instructions included with thermostat.)

To Clear An “SF” Error—FoUow the buUt-in thermostat
manual to find the correct rotary switch position and reset

the desired setting. Then return the rotary switch back to
position #0.

Time Clock—The time clock should be accurate to within 10
minutes per year. During a power faUure, the time wiU be
maintained for a minimum of 8 hours, after which it may be
necessary to reset the clock, (Ref. thermostat instructions).

If the clock is not keeping accurate time, m^e certain the

power has not been off for over 8 hours. If it has not, then
replace the thermostat.

Set-Back—If the thermostat never goes into set-back make
certain: '

The set-back override jumper has been removed from the
connector board. ,

The thermostat hasn’t been programmed to be continuously

in the comfort mode.
The thermostat is set for the proper time of day.

If the thermostat never comes out of set-back make certain:
A set-back On/Off program has been entered.

The thermostat is set for the proper time of day.

STEPS System Troubleshooting

TABLE OF CONTENTS

Self-Diagnostics—Description

Diagnostic Error Codes Page

Error Codes 3, 4—Outdoor Coil, Suction
Thermistor Failure
Error Code 5—Indoor Coil Thermistor FaUure
Error Code 8—Locked Compressor Rotor
Error Code 9—Overcurrent Trip

Error Code 10—Contactor Control FaUure.................

.......................................................

..........

...................

............................ .22-23

.16-17

18-19
20-21

24-25

Error Code 11—Reversing Valve Failure
Error Code 14—Indoor Coil Freeze

Error Code 15—Low Refrigerant Charge

...................

................................

..................

29-31

26-27

28

System Malfunctions with No Error Code

No LED on power-up.....................................................32-33

No Indoor Blower Operation........................................34-35

Electric/Gas Heat Failure..............................................36-37

Miscellaneous Malfunctions

..............................................

39

BEFORE TROUBLESHOOTING THE SYSTEM

This troubleshooting guide covers all components of the
38EV/QV variable speed system, including outdoor and
indoor units.

See previous section for thermostat troubleshooting. (Ther

mostat Error Codes HF and SF).

A WARNING

High voltage (300VDC) circuit remains energized after

main disconnect is opened. Normal capacitive discharge
time is ten (10) minutes, but this period may be
extended indefinitely by component failure. Before
servicing, always check with D.C. voltmeter between
contactor terminal #23 (violet wire) and ground. Always

reinstall safety shield in top of control box after servic
ing. Electrical shock can cause personal injury or death.

Before replacing components to correct a system malfunc
tion, always inspect circuit for damaged or oorroded wiring.
Connectors should be inspected for improper mating. They
should then be unplugged and examined for corrosion, dam
age or incomplete terrhinal insertion. This procedure is espe
cially required when a system malfunction is intermittent
(does not occur consistently).

Clean and/or repair wiring as required. A special accessory
terminal kit (Carrier Service Part No. 38QV660001) includ

ing terminal extraction tools is available through your local,

distributor.

Use high quality multimeter for troubleshooting electronic
devices in this system.

Self-Diagnostic Error Codes—

Error codes are indicated at an LED located on the outdoor

unit main control board (Ref. Fig. 5), and on the indoor ther

mostat display (Ref. Fig. 20).
Control board LED error codes are shown as a series of %

second on, % second off flashes, followed by a 10-second

pause before repeating.
Thermostat display error codes are shown as a two-digit

number, preceded by “HP” on 38QV heat pump systems or
“AC” on 38EV coohng-only systems.

As an example, when an error Code #5 is diagnosed,

“HP05” or “AC05” will be displayed at the thermostat

when 5 flashes are indicated at the control board LED.

Automatic System Restarts on Diagnostic Shutdown—

AU diagnostic shutdowns described in this text wfll cause as
many as five restarts before final shutdown and compressor
lockout. The system wfll remain off for at least five minutes
(time guard function) before attempting each restart.

Note that the control board LED wfll display the error code

after each shutdown. The thermostat display will indicate

an error code only after final compressor lockout.

A CAUTION

Whenever troubleshooting system with power on and
control board LED flashing error code, check ther

mostat display. If error code is not indicated at thermo

stat, automatic restart is pending. Servicing of equip
ment at time of automatic restart may cause personal
injury.

How to “Clear"Error Codes—

Indoor unit power (i.e., controLpower) must be broken and

reset in order to cancel system lockout on a diagnostic.

. The-Self-Diagnostics, feature is designed .to monitor inputs

(thermistors and inverter alarm) and take over control of the
system if these inputs go out of normal range.

Table 4 lists each of the Self-Diagnostic error codes, the con
ditions, that cause the code, and how the system reacts to
each condition.

Troubleshooting System withRower On—

Always bredk power to both indoor and outdoor units when
servicing, except as indicated in the following procedures.

Table 4—Self Diagnostic Error Codes

ERROR

CODE DESCRIP TION

3
4

5
8 Locked C ompressor Rotor Inverter alarm—on within 2 minutes after contactor

9

10 Contactor Control. Failure No change in thermistor readings (See Note 2)-

11

14

15

NOTES:

* System attempts 5 restarts (each followed by 5 minute timeguard) before lockout and error code display on thermostat.

1. Inverter alarm comes on at 100% of rated inverter output-current. Control board ramps compressor speed down until alarm goes off at 85% of rated
current. If control board drops compressor speed to minimum and alarm remains on, it knows inverter has tripped, and shuts system down. (Inverter

trip requires reset of inverter power through contactor to shut off alarm).

2. Control board compares thermistor readings after 5 minutes of run time to readings taken at startup (contactor energization).

O.D. Coil Thermistor Failure

Suction Thermistor Failure
i.D, Coil Thermistor Failure

Overcurrent Trip -

Reversing Value Failure

indoor Coil Freeze

Low Refrigerant Charge

Thermistor reads greaterthan 160'’F or less than -dO^F '
Same as above
Same as above

energization
Inverter alarm—on after 2 m inutes of run time (See Note 1) Compressor slows down to cancel alarm. If alarm stays on system shuts down.

O.D., IrD. Coii Thermistor readings change in wrong
directions (See Note 2).

Suction Thermistor reads less than 32°F in Cool Mode. Blower speeds up to raise suction temperature above 35°F. If so, blower continues

Suction thermistor reads much higher than I.D.
coil (cool), or O.D. coil (heat) thermistor.

CAUSE ^ SYSTEM REACTION

: Immediate Shutdown or no startup*

Same as above*' - - ■

Same as above*

Sameasabove* -

Immediate Shutdown or no startup*

Com pressor speeds up to shift valve. If thermistor readings don't switch direction,
system shuts down.* - - ■

operation at higher speed. If not, .system shuts down.*'
No effect on system operation. Error code on control board LED only.

'I

Fig. 21 — Error Codes 3 and 4

16

ERROR CODE #3 - OUTDOOR THERMISTOR FAILURE
ERROR CODE #4 - SUCTION THERMISTOR FAILURE
REASON: CONTROL BOARD READS THERMISTOR TEMPERATURE ABOVE 160T OR BELOW -40T.

POSSIBLE CAUSES:

1) Thermistor failed or out of calibration (see Note 1).

2) Loose or corroded connection.

3) Faulty control board.

Reference Figure 21

Notes:

1) If thermistor is out of caiibra:tion, it may read accurately when system Is off, but may drift from actual

temperatures during operation.

2) COOL MODE: Monitor temperature at unit service valves.
HEAT MODE: Monitor temperature inside unit at thermistor location.

3) Adjust thermostat 4°F or more above or beiow room temperature, depending on mode, to force system

to high speed.

4) if unit has been off a short time, allow refrig, temperatures to stabilize.

A87475

ERROR CODE #5 - INDOOR THERMISTOR FAILURE
REASON: CONTROL BOARD READS TEMPERATURE ABOVE ISCTF OR BELOW -SCTF.
POSSIBLE CAUSES: 1) Thermistor failed or out of calibration (see Note 1).

2) Loose or corroded connection.

3) Faulty control board, Interface board or cable.

Reference Figure 22

Notes:

1) If thermistor Is out of calibration, it may read accurateiy with system off, but may drift from actual

temperatures during operation.

2) For furnace appiications - Remove furnace access panei and tape kili switch so that panel can later be

removed for blower inspection without breaking power.

Reinstall access panel.

3) Adjust thermostat 4°F or more above or below room temperature, depending on mode, to force system

to fuli speed.

A87477

fi

J

20

ERROR CODE #8 - LOCKED COMPRESSOR ROTOR Reference Figure 23
REASON; OVERCURRENT OR UNDERCURRENT SITUATION OCCURS DURING FIRST 2 MINUTES OF COMPRESSOR

OPERATION.

POSSIBLE CAUSES; 1. Loose high voltage lead

2. -036 Models; scroll compressor running backwards

3. Failed compressor

4. Failed inverter

I 1

V.

Notes;

1) Inverter alarm may be monitored using DC voltmeter at@, in Figure. Alarm-on is 1VDC. Alarm may energize before

inverter trips.

Inverter trip LED (yellow) may be viewed by removing safety sheild from upper control box. View downward into box,
beyond contactor and under main control board at inverter board. See Figure 7 for LED location.
Power (red) LED should light whenever contactor closes.

Power and Trip LED’s will go off when contactor de-energizes.

2) When contactor energizes, inverter output voltage will increase gradually for about 30 seconds before leveling off.
Inverter may trip on low current at about 10 seconds. as7478

YEL

HIGH VOLTAGE
CONNECTOR

(LOWER CJONTROL BOX:

Fig, 24—Error Code 9

Q

A87458

n

ERROR CODE #9 - OVERCURRENT TRIP
REASON; OVERCURRENT SITUATION AFTER FIRST 2 MINUTES OF RUN TIME.
POSSIBLE CAUSES: 1) Defective compressor or inverter.

2) Failed control board.

3) loose or corroded high voltage or inverter alarm connection.

4) Excessive loading due to:
Cool Mode - improper fan operation, dirty outdoor coil, overcharge.
Heat Mode - improper blower operation, dirty air fiiter, blocked duct, overcharge.

Reference Figure 24

Notes:

Inverter alarm may be monitored using DC voltmeter at(A)(see Fig). Aiarm-on is 1 VDC. Alarm may ener

1)

gize before inverter trips.
Inverter trip LED (yellow) may be monitored by removing safety sheild from upper control box. View

downward into box, beyond contactor and under main control board at inverter board. See Figure 7 for

LED iocation.
Power (red) LED should light whenever contactor closes.
Power, Trip LED’s will go off when contactor de-energizes.

Adjust thermostat 4°F or more above or beiow room temperature, depending on mode, to force system to

2)

fuil speed. kmm

• - NO CONNECTION

« - CONNECTION ON 38QV ONLY

(WIRE NUT CONNECTIONS - 036 ONLY -

INSIDE COMPRESSOR CONTROL BOX)

SUCTION LINE)

3BQV - (LOCATED ON

SERVICE VALVE
LIQUID LINE)

Fig. 25—Error Code 10

LIQUID LINE)

38QV - (LOCATED ON

COMPRESSOR
DISCHAROE LINE)

A87473

ERROR CODE #10 - CONTACTOR CONTROL FAILURE
REASON: THERMISTOR TEMPERATURES DID NOT CHANGE AFTER 5 MINUTES OF RUN TIME,

(i.e. REFRIGERANT NOT CIRCULATING IN SYSTEM) see Note 4.

POSSIBLE CAUSES: 1) Failed contactor, or control board output.

2) High, low pressure, or ESS (-036 only) switch.

3) Very low charge.

4) Stuck reversing valve.

Reference Figure 25

U

1) inverter POWER (red) LED can be viewed from above the control box. CAREFULLY remove white safety shield.

Look downward into box beyond contactor and behind main controi board at inverter board. See Figure 7

for LED location. Red LED shouid be on whenever contactor is energized, and outdoor unit power is on.

2) ESS - to - LPS spiice is iocated in compressor terminai box.

3) -036 Modeis Oniy
If compressor has been serviced or repiaced, check for proper 3-phase wiring connections.
If leads are miswired, compressor will not pump in reverse direction.

4) Error code may not appear untii up to 5 minutes after startup (outdoor fan energizes).

A87474

1

REV n/10/87

® - NO -CONNECTION ..

e - CONNECTION ON 38QV ONLY

UNIT CONNECTOR

Fig. 26—Error Code 11

OR

REVERSING VALVE

SOLENOID CRVS)

(LOCATED ON 4-WAY

VALVE) C38QV UNITS)

A87459

ERROR CODE #11 - REVERSING VALVE FAILURE (38QV HEAT PUMPS ONLY)
REASON: INDOOR THERMISTOR DOES NOT DROP IN TEMPERATURE AFTER SYSTEM STARTUP (COOL

MODE ONLY) see Note 1.

POSSIBLE CAUSES: 1) Reversing valve stuck.

2) Reversing valve coil not energizing.

3) Indoor thermistor not installed property.

:f I

Notes:

1) Error code may not appear until up to 5 minutes after startup.

A87466

ERROR CODE # 14 - INDOOR COIL FREEZE
REASON: SUCTION THERMISTOR READS BELOW 32° F.

POSSIBLE CAUSES; 1) Blocked return or supply duct.

2) Dirty air filter.

3) Suction thermistor out of calibration (see Note 1).

Notes: kzim

1) If thermistor is out of calibration it may read accurately with system off, but may drift from actual during operation.

ERROR CODE #15 - LOW REFRIGERANT CHARGE (see Note 1).
REASON: LARGE REFRIGERANT TEMPERATURE RISE THROUGH INDOOR COIL (COOL MODE),OR OUTDOOR COIL

(HEAT MODE).

POSSIBLE CAUSES: 1) Low refrigerant charge.

2) Plugged or failed solenoid expansion valve (SEV).

Notes:

1) Error code will not affect system operation, and will only be displayed at control board LED.

2) Superheat Tables provided in outdoor unit installation instructions.

3) In outdoor ambients below 75-80°F in Cool, above 45°F in Heat, system will not go to full speed, and SEV should be

cycling on-off.

4) Refer to Figures 15 and 16 to see location of valve orifices. Valve main orifice may be cleaned by blowing air, etc. into

outlet of valve. If this is unsuccessful, replace valve.

------------

A87471

PUSH A SHARP OBJECT
INTO WIRE TERMINAL
HERE TO UNLOCK AND

■ f

REV 11/10/87

CLOCATED ON SERVICE

VALVE LIQUID LINE)
C38QV UNITS ONLY)

»

A87460

Fig. 27—Outdoor Unit Soienoid Expansion Vaive (SEV)

(if

(ERROR CODE #15 CONTINUED)

38QV UNITS ONLY

Reference Figure 27

Note:

5) Superheat should be less than 5°F, but may be up to 10°F in above 40°F outdoor temperatures.

A87470

22-30 VAC CIRCUIT

(TERMINALS #1,2)

1 \2 3 4 5 S 7 8

rrniITT

CONTROL BOARD

PLUG

(A)

OUTDOOR UNIT

MAIN

CONTROL BOARD

8 7 8 5 4 3 2 1

1 111 ITr T

)

22-30 VAC

(TERMINALS #1,2)

©

ut

___________

NTERFACE BOARD

RECEPTACLE

1

)

■ 208/230 VAC

....

INPUT

TRANSFORMER

Q)

A87461

Fig. 28—Control Board LED Does Not Light

Notes:

1) For 208VAC applications •* Check (2) transformers at indoor unit to make sure red (230VAC) transformer lead connections

are replaced by blue (208VAC) transformer leads.

2) For furnace applications - Remove furnace access panel and temporarily tape kill switch so control power can be sup
plied to outdoor unit. A87467

SPEED ON-OFF

O DODO O'O 0,

p 2 3 4 5 6 7 a/

\o O O O O o o_7

V 9 10 11 12 13 14 Iff

CABLE CONNECTOR

ON-OFF SPEED

1-14 VDC .1-14 VDC

TTiiYiii-

■

/ )L Jl /

INTERFACE BOARD

INTERFACE

BOARD

INTERFACE BOARD

TEST POINTS

SPEED

1-14 VDC

ON-OFF

-.1-14 VDC

INTERFACE BOARD

CONNECTOR

iCj

BLOWER

SPEED ON-OFF

r

CONTROL BOARD

CONTROLLER

OUTDOOR UNIT

MAIN

CONTROL BOARD

PINS

MOTOR

RESISTANCE

©

COHMS)

1-2
1-3 OPEN
1-4 OPEN
2-3

2-4

CONTROL BOARD

J

TEST POINTS

3-4
5-6

OPEN

9-14

9-14

9-14

0

j

H? (d

-,5 -2
5 3

MOTOR

CONNECTOR

1 1

Fig. 29—Indoor Blower Failure

A87462

INDOOR BLOWER FAILURE

f V Reference Figure 29

Notes;

On some models, removal of blower housing is required to determine if wheel is rubbing.

1)

Refer to indoor unit installation instructions for service and repiacement procedures:

2)

For fan coiis without eiectric heat, piace (2) jumpers at Interface board from L1 to C, and L2 to 1 (or 2).

3)

If Neither Speed or On-Off signals are present, wait longer and recheck, as it could take 2-3 minutes for blower to start in

4)

some cases, ■
if biower starts, break power, remove jumper and place between R and W2(or W). Reset power and check to see that

5)

electric or gas heat operate. If not, refer to “Electric/Gas Heat Failure.”
Voltage at C and 1 (or2) may also be read by removing interface box cover and reading at solder joint connections on

6)

board. A87469

CONTROL BOARD

S.TS15 R.DUELL 11/10/07

Fig. 30—Electric/Gas Heat Failure

A87463

ELECTRIC / GAS HEAT FAILURE
Reference Figure 30

Notes:

1) For furnace applications - Tape the kill switch under access cover so unit can be started and inspected during opera
tion.

2) For furnace applications - Blower will go to high speed 2-3 minutes after burner ignites.

/-• V:

u

Fig. 31—Outdoor Fan Circuit

©

MISCELLANEOUS MALFUNCTIONS

1) LED stays on after power up.
Reason; Malfunction of communications between thermostat and outdoor unit main control board.
Check For:

A. Improper wiring of thermostat.
B. Loose/corroded connection at:

• thermostat

• indoor unit interface board

• Interface cable at indoor or outdoor unit

C. Defective controi board or thermostat (see Thermostat Section).

2) Compressor does not operate.

• See Error Code #10.

3) Outdoor fan does not operate.

• Fan motor is standard single phase component. Check for failed motor, capacitor, or control board using

Figure 31.

4) Compressor and outdoor fan do not operate.

• Initiate “Run Test” jumper. If either component operates, follow checkout procedure for the failed component
in this section. If neither operates replace control board. If both operate, and control'board LED goes off, unit
is not receiving capacity demand from thermostat. Make sure proper Heat or Cool switch is in “Auto” at

thermostat, and setpoint is at least 2°F away from setpoint. Pull “Speed-Up” jumper to bypass 5 minute
timeguard. If unit does not start within 5 minutes, Follow same procedure for #1 above, “LED stays on after

power up.”

5) Compressor cycles on-off, outdoor fan stays on.

• Compressor is cycling on safety device. See Error code #10 and Figure #25 to investigate excessively high

or low pressures. Check for proper charge, failed fan, blower or failed/plugged solenoid expansion valve.

6) Thermostat display malfunction.

• See thermostat troubleshooting section and instructions included with thermostat.

7) Rev/efsirig válvé does hot operate.

• See Error Code #11.

8) Indoor coil freezing.

• See Error Code # 14.

9) System running abnormally low suction pressures.

• See Error Code #15.

'4. ^

A87465

STEP 6—Service And Maintenance

TABLE OF CONTENTS

38EV, 38QV Outdoor Unit Service and Maintenance Page

—Replacement of:

Service Valves......................................................................40

Refrigeration Cod

Control Box..........................................................................40

Outdoor Pan........................................................................41

Compressor

Reversing Valve

Main Control Board...........................................................41

Thermistors............ ...........................................................41

Contactor.............................................................................42

Emergency Stop Switch (ESS)...........................................42

Solenoid Expansion Valve (SEV)

Outdoor Unit

Indoor Unit

Interface Cable....................................................................42

Low, High Pressure Switches
Crankcase Heater, Switch and Fan Motor

Electrical Terminals, Connectors......................................43

—Elimination of Television, Radio Interference
—Maintenance:

Fan Motor Lubrication 43

Compressor Oil. .. ...........

Coil and Heat Sink Cleaning............................................. 43

40 QV Fan Cod, 58SSB blower Accessory Service

and Maintenance.....................................................................44

38EV, 38QV Outdoor Unit Service and Maintenance
NOTE: Malfunction of certain electronic control compo

nents can cause lack of Automatic Emergency Heat initia
tion. See below for corrective servicing procedures.

Component replacement and maintenance procedures are
covered in this text. Refer to 38EV or 38QV Instadation
Instruction for the foUowing procedures:

—System Startup Checkout
—System Charging
—Optimizer, Electric Heat Lockout Setup
—Blower Speed Checkout, Adjustment

Manual Emergency Heat Activation—

38EV and 38QV systems are designed to automaticaUy pro
vide emergency gas or electric heat in the event of compres
sor lockout on a system malfunction.

However, certain system control malfunctions may cause

lack of emergency heat initiation.

In the event that replacement parts are not readdy avadable

in the heating season, malfunction of the main control board
or interface cable can be manuaUy bypassed as described
below to restore gas or electric heat operation.

Note, however, that a malfunction of the interface board

causing inability to control blower speed, or fadure of

blower motor or controUer cannot be bypassed and must be

repaired.

Install a standard thermostat in the heated space for tempo
rary control untd the system can be repaired. Connect ther
mostat leads to the indoor unit terminal board across R and
W, as connected in conventional systems. The interface

board wdl control gas or electric heat to setpoint of the tem
porary thermostat.

COMPONENT REPLACEMENT
Before replacing any component in the entire system, turn
off main power to system. There may be more than one dis

connect switch. Turn off accessory heater power, if

...............................................................

.........................................................................

..................................................................

......................................

...................................................................

......................................................................

............................................

......................

.............

...........................................................................

40

41

41

42
42

42
43

43

applicable.

A WARNING

High voltage circuit remains energized after main dis
connect is opened. Normal capacitive discharge time is
ten (10) minutes, but this period may be extended indef

initely by component fadure. Before servicing, always

check with D.C. Voltmeter between contactor terminal
#23 (violet wire) and ground. Do not service until read
ing is lOVDC or less. Electrical shock can cause per
sonal injury or death. Always re-install safety shield in
top of control box after servicing.

A CAUTION

Aluminum tubing is used in unit cods. Do not overheat
or place excessive strain on tubing or damage may

result.

NOTE: To remove reversing valve, accumulator or compres

sor, control box and coil must be removed first. Coil
removes quickly and easdy. The minimal time required for
cod removal facilitates service and component removal. See
instructions below.

SERVICE VALVE REMOVAL-Cod must be removed to

remove screws holding service valves.

COIL REMOVAL

1. Shut off power to indoor and outdoor units.

2. Remove refrigerant from unit, using refrigerant
removal methods described in Carrier Standard Service
Techniques Manual, Chapter 1, Refrigerants. Be sure
system is 0 psig before proceeding.

3. FoUow steps 4 through 12 below.

CONTROL BOX REMOVAL

Make sure power is off to indoor and outdoor units.

4. Remove control box cover (3 screws).

5. Disconnect (3) in-hne electrical connectors in lower con
trol box.

6. Disconnect power leads and interface cable if control
box cannot be removed and set aside with them
attached.

7. Remove (8) screws securing control box to louvered cas
ing and (2) securing support legs to base pan.

43

A WARNING

High voltage circuit remains energized after main dis

connect is opened. Normal capacitive discharge time is
ten (10) minutes, but this period may be extended indef
initely by component failure. Before servicing, always
check with D.C. Voltmeter between contactor terminal
#23 (violet wire) and ground. Do not service until read
ing is lOVDC or less. Always re-instaU safety shield in
top of control box after servicing.

8. Supporting control box with one hand, remove safety
shield and (2) top screws securing box to fan orifice

ring. Remove control box by sliding horizontally away

from unit.

NOTE: Before reinstalling box, gray plastic through-the­coU vent tube must be removed from control box. Do this by
squeezing top and bottom of vent where it protrudes from

rear of box. Then slide vent out through front of box, taking

care not to damage wires.

Once the box is fuUy reinstalled, slide vent into slot in rear
of box and through existing opening in coil. Make sure front

lip of vent is against rear panel of box.

/tn

OUTDOOR FAN/MOTOR REMOVAL—

Make sure power is off to indoor and outdoor units.

9. Remove fan/motor/orifice assembly by removing
remaining 4 screws around orifice assembly. (If control
box is not being removed, remove safety shield, and (2)
screws in upper control box). See Warning, above.

Unplug motor wires from base of motor prior to lifting out
assembly.

Remove Coil—

Cutting tubing is recommended to avoid possibility of

fire, and personal injury.

10

Use midget tubing cutter to cut liquid and vapor lines
at either side of coil. Cut in convenient location for easy

reassembly with copper slip couplings.

11.

Remove 4 screws around base pan securing louvered
casing and wire coil wrap. Set louvered casing aside.

12. Lift coil vertically off base pan and place carefully to
one side.

NOTE: While coil is removed from unit for intended service,

use this opportunity to remove and replace strainer.

COMPRESSOR REPLACEMENT

Check whether

tiedown bolts/

1. Remove control box, fan and coil as described under

Cl

“CoU Removal” above.

2. Disconnect electrical leads from compressor.

Compressor is Srphase—Note lead locations for proper

wiring of replacement compressor.

-024 Models: T1 — Black

-036 Models: U — Black

3. Cut compressor suction and discharge tubes at conven
ient location.

4. Loosen and remove crankcase heater (-036 models
only).,/ /

5. Remove compressor mounting bolts.

6. Lift compressor out.

7. Carefully unbraze suction and discharge fine piping
stubs frora compressor. Note position of stubs to assist
when reinstalling.

8. Install new compressor. Install crankcase heater
around compressor (-036 models only). Install compres
sor mounting bolis.

9. Braze suction and discharge fines to compressor (where

unbrazed in Step 7) and piping stubs (at point where
cut in Step 3 above). Rewire compressor.

10. Replace coil,;braze liquid and vapor line. Test for leaks.

11. Replace fan/motor/orifice assembly.

12. Replace control box and reconnect wiring., (See note
above, under “Control Box Removal.”)

13. Evacuate and recharge system

À WARNING

A CAUTION

unit is fastened to platform with

Wire

Marking Color

.....

:T2~WeUbw

T3 — Blue

V —Yellow
W -Blue

......

INSTALL FILTER DRIER-Install field-supplied heat
pump filter drier in system liquid fine when refrigerant sys
tem is opened for service as described under “Compressor
Replacement,” above. Position drier in liquid fine at conven
ient location.

REVERSING VALVE REPLACEMENT (38QV Only)

1. Remove coil as described in “Coil Removal,” above.

2. Cut 4 legs of valve using midget tubing cutter.

3. Wrap replacement valve with wet cloth to prevent
overheating.

4. Replace new valve using tubing slip couplings.

MAIN CONTROL BOARD REPLACEMENT

a) Unplug Interface Cable from bottom L.H. side of board

by sfiding small metal retainer right.

b) Unplug white 17 pin connector and two fan motor

push-on leads (Black) from top of board. Use caution to
prevent board damage when removing connections.

c) Using fingers or small tipped pliers, depress plastic

tabs on board standoffs (4) on corners of board and (1)

near center (below black heat sink on board). Lift board

out of position.

d) Align new board on plastic standoffs, and push board

down over standoffs until small locking tabs secure
board in place.

e) Reinstall 2 (black) fan wires and white connector at top

of board. Be sure white connector is aligned correctly.
Reinstall interface cable, sfiding metal locking retainer

to the left.

f) Cut only those program jumpers on new board (ref.

Fig. 5) which were cut on old board.

A CAUTION

Failure to cut the proper programming jumpers wffl

result in improper operation. Jumpers not cut on the

old board must remain uncut. Inadequate operation and

equipment damage may result.

Jumper functions are fisted, in. Table , 3 for reference

.

purposes.

g) Set Optimizer Pot (ref. Fig. 5) on 38QV Heat Pump

units if jumper, jJ4 or J5 is cut. Adjust to same setting
as old board, or refer to procedure for optimizer or elec
tric heat lockout setup in 38QV unit Installation
Instructions.

Table 5—Programming Jumpers

Jumper

No.

J1

J2,J3

J4
J5

J6, J7

*38QV Systems only

THERMISTOR REPLACEMENT

a) Break power to indoor and outdoor units.

b) For outdoor unit thermistor replacement, remove top

grille.

c) Cut plastic ties holding foam tube over thermistor.

Thermistor is mounted inside %e" copper tube soldered
to refrigerant fines and is retained by one (1) plastic tie.
Remove this tie and remove thermistor.

38QV Heat Pump

Systems

UNCUT CUT
UNCUT

CUT FOR 58SSB FURNACE APPLICATIONS

' CUT FOR ELECTRIC.
HEAT LOCKOUT AT HIGH

OUTDOOR TEMPERATURES*

UNCUT UNCUT

38EV Cooling

Systems

UNCUT

UNCUT

d) Cut thermistor leads about 12" back from end. Cut

replacement thermistor leads to about 16" long, strip

back all leads, and splice leads together with a crimp­type connector. Use silicone sealer in connector to
make it waterproof.

e) Re-insert thermistor into %e" tube, retain with (1) plas

tic tie around wires and refrigerant tube. Be sure

thermistor is not sticking out end of tube. Fill both
ends of small tube with petroleum jelly and similar.

f) Wrap thermistor tube with same 3" piece of armaflex

insulation, or similar. SUt of foam insulation must be
on opposite side of refrigerant tube from thermistor

;weU. -Tie in-place-with (2) plastic-ties-as-before.

CONTACTOR REPLACEMENT

Break power to indoor and outdoor units, and remove con
trol box cover.

a) Disconnect aU wires to contactor noting attach point to

component. Refer to unit wiring diagram. Loosen upper
left mounting screw and remove lower right screw.
Remove contactor and replace.

b) Rewire contactor following unit wiring diagram.

A CAUTION

Make sure contactor wiring is correct before starting
unit. Left side of contactor (terminals #11 and #21) of
contactor is for 230 VAC input power. Right side (ter

minals #13 and #23) is 300 VDC supply to inverter

board (violet wires).

EMERGENCY STOP SWITCH (ESS) REPLACEMENT

(38EV036 and 38QV036 Only)

a) Break power to indoor and outdoor units.

b) ESS .switch is in series with low pressure switch arid is

connected with wire nuts within the compressor junc
tion box. Remove unit top grille and compressor sound
shield. Switch is located on top of compressor under a
special rnetal clip with white wires going to junction

box.

b) Push switch (rectangular aluminum body) toward wire

end and it will slip out from under clip.

c) DO NOT remove wires from compressor junction box.

Cut white wires about 6" out of box.

d) Slidé new switch under clip until it hits stop at end of
i . cHp. ''i":';-V ■

e) Re-wire switch to old white wires out of compressor

junction box with wire nuts. Note wires are #20 gage so
use appropriate nuts. Fill connector cavity with sili
cone sealer.

f) Replace sound shield and top grille.

EXPANSION VALVE COIL REPLACEMENT

a) Break power to indoor and outdoor units. For outdoor

SEV replacement, remove top grille.

b) Reiriove nut holding solénoid on body of valve. Cut

wires about 12" away from coil.

c) Replace with new solenoid. Cut leads of new coil to

about 16" long. Splice with crimp-type connectors.
Reinstall nut and harness wires as before. Use silicone
sealer in connector cavity.

d) Replace top grille (for outdoor SEV replacement).

ELECTRONIC.EXPANSION VALVE REPLACEMENT
38QV OUTDOOR UNIT-

See Figs. 2 and 3 for Locations of Outdoor Unit SEV.

a) Break power to indoor and outdoor units.

b) Remove top grille.

c) Remove system charge using proper procedures.

-----—

d) Remove solenoid coil. Using two (2) wrenches, loosen

the flare nuts holding valve to tube. USE CARE to not
twist tubing. Remove valve. Remove piston as you
would in a standard unit when piston is in service

valve.

e) Insert same piston or new piston and new retainer in

new valve. Set valve in liquid line and hand-tighten
flare nuts. Tighten nuts to 10-15 lb. ft. Note: Use care
to not overtighten valve connections, which could

deform valve and bind pistons. This valve must be
mounted with coil in a vertical position as on original
installation. Piston must be at valve end toward serv

ice valve, with arrow on valve body toward coil. Rein
stall solenoid coil, and top grille.

f) Recharge system.

Indoor Location—

The indoor SEV valve is located on the liquid line at the

indoor coil.

38QV Heat Pump Systems—foUow procedure for outdoor
unit SEV replacement, above. When installed, new valve
should have arrow on body toward indoor unit, accurator

piston end facing toward outdoor unit.

38EV Cooling Systems—

a) Break power to indoor and outdoor units.

b) Remove system charge using proper procedures.

c) Remove thermistor insulation by cutting tie wraps.

Cut tie wrap securing thermistor leads to line, and slide
thermistor out of well.

d) Remove solenoid coil. Using two (2) wrenches loosen

flare nuts holding valve assembly in place. Use care not
to twist indoor unit fitting. Remove valve assembly.

e) Carefully unbraze valve from assembly tubes and braze

in new valve.

f) Set valve in Hne and hand-tighten flare nuts. Tighten

nuts to 25-30 Ib-ft.

g) Reinstall thermistor, insulation, and solenoid coil.

h) Recharge system.

INTERFACE CABLE-

a) Break-power to outdoor and indoor units.

b) Disconnect interface cable from outdoor unit control

board by sliding locking latch to right. Disconnect
ground wire. Loosen black plastic nut on cable strain
relief and remove cable from slot in box. The new cable
will have a new strain relief attached.

c) Disconnect interface cable from indoor interface con

trol box by squeezing the metal tabs on the cable end.
Unfasten cable black ground wire with ring terminal
from sheet metal screw. Route cable out through hole

provided in cabinet.

d) Remove ALL ties securing cable to refrigerant lines

and remove cable from instaflation.

e) Connect new interface cable to outdoor unit control

board. This cable is polarized so it will only go on one
way. Slide metal retainer left to retain cable. Reattach
black ground wire to sheet metal screw. Loosen black

plastic strain relief nut on cable, set in slot on box and

tighten nut. Use care to not put excess strain on con
trol board.

f) Working from outdoor to indoor unit, secure cable to

refrigerant lines every 2-3 ft. using tie wraps, or
similar.

g) Connect cable to indoor interface control board. Route

cable through holes provided in unit as before. This
cable end is also polarized so it will only go on one way.

Squeeze clips on cable and insert in receptacle on box.
Reattach black ground wire to sheet metal screw,

LOW AND HIGH PRESSURE SWITCH, REVERSING

VALVE SOLENOID

: ' These components are the same as on any Carrier unit, and

can be replaced using normal procedures with the following
exception:

The wiring back to the control box is through a 15 pin
plug connection, so the wires must be cut within 12 to 15
inches of component and replaced with new part using
wire splice with crimp-type connection. Use sihcone sealer
in connector cavity.

CRANKCASE HEATER SWITCH, CRANKCASE HEATER,

FAN MOTOR

Crankcase Heater Switch: One lead goes to junction box on
compressor, attached with wire splice. Replace as required.

a) The second wire is connected to the control box

through a six pin plug connection. Note location of

CHS on liquid tube. Remove switch with pliers squeez
ing clip as on a standard unit. Cut wire about 12 to 15
inches away.

b) Install new switch. Cut leads to 15 inches and splice to

unit leads. Use splice with crimp-type connection. Fill

splice cavity with silicone sealer to make splices

waterproof.

Crankcase Heater: These components are the same as on a
standard unit. Replace as required. Cut leads back 12" from
component and splice in new heater leads. Seal splice con
nections with sihcone.

Electrical Terminals (Within Unit Plugs)

I To repair terminals within the three (3) unit plugs in the out

door section and plug on interface box in indoor section a

terminal kit is available from Service Parts.,#38QV660001.
This kit contains 12 each of every plug and receptable termi

nal used within system. Also included is a removal tool for
terminals inside receptacles.

Possible Television, Radio and Home Computer Screen
Interference

NOTE: This equipment generates and uses radio frequency

energy. If not installed properly, it may cause interference
with TV and/or radio reception. This system has been

designed to provide reasonable protection against such
interference in a residential installation. If this system does
cause such interference to TV and/or radio reception, which
can be checked by turning the system on and off, check the
following;

Check Interface Cable—

a) This cable has a black ground lead that is attached to

the sheet metal on both the outdoor unit and indoor
unit. Check that the lead is properly installed and not

insulated by a painted surface.

b) If installation uses two (2) interface cables connected

together, the middle connection has two black ground

wires that must be connected together with the pro
vided bolt, nut, and lockwasher. If not, use a #10 x %"
bolt and locknut.

c) Check that black ground lead is connected to black

plastic plug case. Plastic case can be opened to check
that' wireis connected to cable shielding. If not, replace
cable or fix loose wire with soldering gun. Use care not
to burn wires.

d) Check that cable is installed properly. This cable must

be installed alongside refrigerant tubing and tied to it
as much as possible.

Check Unit Ground Connection—

a) Outdoor Unit: Inside control box cover is an aluminum

lug attached to box. Field ground connection must be
connected.

b) Indoor Unit; (Fan-Coil or furnace) check for similar con

nection inside control box.

Check Indoor Unit Thermostat Wires—

a) System thermostat leads run from interface control

box board (TB-4) on fan coil or furnace kit (see unit wir
ing label) to Parker thermostat. Leads must be
shielded.

b) Thermostat leads leaving interface box must run

through an EMI shield (ferrite-“iron” core—%" O.D. x
%” I.D. X 2%" long.

c) If core is not installed, order from Service Parts

#HK99FA001.

Check Location of Television, Radio or
Monitor to System—

a) If cable shielding and EMI shield are not in place, this

system is designed to not interfere if appliances are 30
ft and one wall away from system (indoor or outdoor
units).

b) Move TV receiving antenna to eliminate interference.

c) Check that TV, radio or monitor are not on the same

electrical circuit as the system.

d) Ensure that cable grounding and EMI shield are

installed.

Check Other Computer or Signal Generating

Devices In House—

a) Appliances hke modern dishwashers, dryers, sewing

machines, power tools, room air conditioners can emit
the same signals.

b) Check that these appliances are not on the same electri

cal circuit as the system.

MAINTENANCE

A WARNING

Before performing recoromended maintenance, be sure

unit main power switch is turned off. Failure to do so
may result in electric shock, injury or death from rotat
ing fan blade.

Lubrication

FAN MOTOR BEARINGS—Oiling holes are provided at

each end of condenser fan motor. Remove fan motor and
lubricate motor with 32 drops (16 drops per hole) of SAE-10
riondetergent oil at intervals described below.

a) Annually wheii environment is very dirty, ambient

temperature is higher than 105 F (40 C), and .average

unit operating time exceeds 15 hours a day.

b) Every 3 years when environment is reasonably clean,

ambient teinperature is less than 105 F (40 G) ^d unit

operating time averages 8 to 15 hours a day.

c) Every 5 years when environment is clean, ambient tem

perature is less than 105 F (40 C) and unit operating

time averages less than 8 hours a day.

COMPRESSOR contains factory oil charge. If oil requires
replenishment, see Table 1 for oil recharge and Carrier
Standard Service Techniques Manual, Chapter 1, Refriger
ants, page 1-21, for instructions. Use proper oil as listed in

Table 1.

Coil and Heat Sink Cleaning to be done at the beginning of

each cooling season or more often if required. (Heat sink is
located between control box and unit.)

A CAUTION

Fin damage can result in higher operating costs or com

pressor damage. Do not use flame, high-pressure water,

steam, volatile or corrosive cleaners on fins or tubing.
Follow these instructions carefully. Contact your dealer
if you encounter problems.

1. Shut off power to unit.

2. Clean coil and heat sink using vacuum cleaner and coil
crevice tool (see Fig. 32). Work crevice tool vertically
making sure tool only touches dirt on coil fins. To pre-

“vent fin-damage, do not “scrub” fins with tool or move

tool horizontally.

3. If oil deposits are present, spray coil and heat sink with
ordinary household detergent. Wait 10 minutes then

proceed to step 4.

4. Using garden hose, spray coil vertically downw;ard
with a constant stream of water at moderate pressure
(see Fig. 33). Keep nozzle at a 15 to 20 degree angle,
about 3-in. (76 mm) from coil face and 18-in. (457 mm)

from tube. Spray so debris is washed out of coil and
heat sink.

5. Restore power to unit.

40QV Fan Coil, 58SSB Blower Accessory Service and
Maintenance—

Refer to related installation instructions for component

replacement, service and maintenance procedures.
For blower speed inspection and adjustment procedures see

related instructions and 38EV or 38QV outdoor unit instal
lation instructions.

Fig. 32—Crevice Tool

A87037

Fig. 33—Positioning Hose to Spray Coil

A87050

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til

COffONENT A RRAN6EHENT

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3 INTERFACE CABLE

T-1

~ —

FIELD POWER WIRINB

--

— •

FIELD CONTROL WIRING LPS
HARKED COMPONENT TERMINAL

0

UN1ARKED C0»f>C»€Hr TERMINAL

splice COWECTION

-< SOCKET TERMINAL
PIN TERMINAL

<•

BP-1,2,4 CIRCUIT BOARD PLUOS

C

CONTACTOR PMWPOWER MODULE 'W'

CM CRAMCCASE HEATER

. CMS

CRAWXA5E HEATER SWITCHRS

C0H»R

INVERTER CC»ff>RES50R 5-B-1

CAP

CAPACITOR
C-B-1CIRCUIT BOARD #1 (HITACHI)
C-B-2

CIRCUIT BOARD *2 CCarrl«r)

cr CLRCKT TRANSFORMER
FC FW CAPACITCR
FR FAN REUY

1. TO BE WIRED IN MXfSMi/X WITH N.E.C. AMD LOCAL CCCCS.

2. COW’RESSOR AMD FAN HOTCR TTBWaY PROTECTED.

3. MUST USE PAI9ZR THERMOSTAT tfHHOSZAOOI.

A. USE SUPPLIED INTEPfACE C/flLE FOR COMCTlOe BETWEEN UNIT AND INDOOR SECTION.

5. USE CJypER «»eUCTORS ONLY i

_BU
“BU

ELU BLU 6U BU BU BU

T-2

LESEND

HPS

MOV
CFHOUTDOOR FAN MOTOR
ore OVER TEMPERATURE CONTROL

P-1,2,3 1NTERCOWCCTINOPLU9S

PMUPOWER HOOULE 'U'
PMV

RS

BLEED RESISTCR
SURGE RESISTOR

SUB - BOARD «1

........

S^2

.

SUB - BOARD 42

SH SHUNT RESISTOR

T-1,2,3T1CRMIST0RS

TB

TERMINAL BLOCK

CP, CMCAPACITOR, fCGATIVE/POSiTI

NOTES

NOTE: Emergency Stop Switch (ESS) used on 036 size only.

-BU

"BU

HI6M PRESSURE SWITCH
LON PRESSURE SNITCH
METAL OXIDE VARISTOR

POWER MODULE 'V”

{ HOOEL HO.

----------—

3eEV500D44 REV E

A87480

Í

Fig. 35—38EV Component Arrangement

Fig. 36—38QV Schematic Diagram

COMPONENT ARRANGEMENT

YEL

OFM

BRH
ELK

f

T-1

I RVS I ELK

,a.K

"ELK

- a-K
' hj:

BL)C

SEV ГаГ"

ESS

LESEND

— —

FIELD POWER WIRINB H»S

—

FIELD CONTROL WIRINB LPS
HARKED CDM>ONENT TERHINAL

0

IMURKED COtf>ONENr TERMINALCFH

SPLICE CCNCOTKIN СПС

-< SOCKET TERMINAL

PIN TERMINAL PMU

BP7b2»4ClRCUIT BOARO PLUBS PHY

■'■c

CCWTACTOft - PHW

CH

CRANKCASE №ATER RB

CHS

CRANKCASE HEATER SWITCHRS

CT

CURRENT TRANSFORMER

C0№R

INITERTER CC»f>R£5S0R S-&-1

CAP

CAPACITOR S>e-2

C-B-1

CIRCUIT BOARD #1 CHITACHI)SEV

O-B-2

CIRCUIT BOARD *2 (Corrltr)SH

esst

EMER8ENCY STOP SWITCH

rc

PAN CAPACITOR ТВ

FR

FAN REUY CP, CNCAPACITOR, NEBATIVE^DSITIVE

1. TO BE WIRED Ж ACCORDANCE WITH N.E.C. AND LOCM. COOES.

2. FAN HOTOR THERNAUY РЛОТЕСГЕО.
Э. HUST USE PARKER TICRNOSTAT «HK05ZA001.
Ч. use EUPFUiD IKTSTACZ CMLE P№ COHCCTlOe КПЕЕН IMIT «Ю INDOOR SECTION.

5. USE COPPER CONDUCTORS ONLY

NOTES

HIBH PRESSURE SWITCH
LOW PRESSURE SWITCH

HOYMETAL OXIDE VARISTOR

OUTDOOR FAN HOTOR
CNER TEMPERATURE CONTROL

P-1,2,3 INTERCCNNECTlNe PLUBS

POWER HOOULE 'U'
POWER HODUU 'V'
POWER HOOULE
BLEED RESief~
SURBE RESISTOR

RVS

REVERSIHB VALVE SOLENOID
SUB - BOARD «1
SUB - BOARD «2

EXPANSION VALVE SOLENOID
SHUNT RESISTOR

T-t,2^3 THERMISTORS

TERMINAL BLOCK

1 MODEL NO. 360V036320

1 38eVS002M REV E

A87481

NOTE: Emergency Stop Switch (ESS) used on 036 size only.

Fig. 37—38QV Component Arrangement

4Я

!i ■
ii '

VVT SINGLE-ZONE WIRING DIAGRAM

WITH 40QV VARIABLE SPEED FAN-COIL

VVT SINGLE ZONE WIRING DIAGRAM
FOR ACCESSORY FURNACE VARIABLE SPEED KIT.

-V

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.

BookI 1 I 1 I 4 I 4 PC 101 Catalog No. 533-895 Printed in U.S.A. Form 38EV, QV-1SM Pg 52 12-87 ' Replaces: New

Tab I3al5al2al5a

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