McQuay ALP-159A Maintenance Manual

BULLETIN NO. IM

173

JULY 1978

INSTALLATION AND

MAINTENANCE DATA

PACKAGED AIR COOLED CONDENSING UNIT

TYPE ALP-067A THRU 159A

GROUP McQUAY-PERFEX Inc. 13600 Industrial Park Blvd., P.O. Box 1551, Minneapolis, Mn. 55440

@)

NOTICE:

Installation and maintenance are to be performed only by

qualified personnel who are familiar with local codes and

regulations,

and experienced with this type of equipment.

CAUTION:

Sharp edges and coil surfaces are a potential

injury hazard.

Avoid contact.

page

2

Nomenclature

PROPELLER FANS
LOW POWER CONSUMING
AIR COOLED CONDENSER

AL

-

089 A D

REFRIGERANT CIRCUITS

(D=Dual;

S=Single)

DESIGN VINTAGE

NOMINAL CAPACITY (TONS)

Inspection

When the equipment is received,

all items should be carefully checked

against the bill of lading to insure a complete shipment.

All units

should be carefully inspected for damage upon arrival.

All shipping

damage should be reported to the carrier and a claim should be filed.
The unit serial plate should be checked before unloading the unit to
be sure that it agrees with the power supply available.

INSTALLATION

Handling
Care should be taken to avoid rough handling or shock due to dropping

the unit.

Do not push or pull the unit from anything other than the

base,

and block the pushing vehicle away from the unit to prevent

damage to the sheet metal cabinet.

(See Figure 1.)

FIGURE 1

SUGGESTED PUSHING ARRANGEMENT

GOOD PUSHING ARRANGEMENT

CABINET DAMAGE UNLIKELY

POOR PUSHING ARRANGEMENT

CABINET DAMAGE LIKELY

page

4

Never allow any part of the unit to fall during unloading or moving
as this may result in serious damage.

To lift the unit,

2+"

diameter lifting holes are provided in the base

of the unit.

Spreader bars and cables should be arranged to prevent

damage to the condenser coils or unit cabinet.

(See Figure 2.)

FIGURE 2

TABLE 1

SUGGESTED LIFTING ARRANGEMENT

SPREADER BAR

REQD.

-MUST USE THESE RIGGING HOLES

(N

OTE

CONTROL 60x

L~cATI~NI

SHIPPING WEIGHTS

ALP UNIT SIZE

UNIT WEIGHT

(Ibs)

067ASlD

4125

078ASlD

4308

089A

4963

106A

5134

ALP UNIT SIZE

126A
136A
149A
159A

UNIT WEIGHT

(Ibs)
6021
6095
6873
7202

Location
Due to the vertical condenser design, it is recommended that certain

precautions be taken before installation to orient the unit so that
prevailing winds blow parallel to the unit length thus minimizing
effects on condensing pressure.

If it is not practical to orient

the unit in this manner,

a wind deflecting fence should be consi-

dered.

It is also necessary to provide adequate clearance on all sides of

the unit for service access and satisfactory performance.

At least

60 in.

(1 fan diameter) should be allowed on each side of the unit

for condenser air inlet and compressor removal on units 067

&

078.
If parallel units are installed side by side, 120 in. should be al­lowed between units.

This will prevent excessive condensing temper-

atures and enhance system performance and operating economy.

Clear-

ance for service access should be at least 78 in. at the control cen-

ter end for compressor removal on units 089 through 159 and 42 in.

on units 067 and 078.

Allow 36 in.

clearance at the end opposite

the control center for ease of access to bearings and drives.

These

clearances are illustrated in Figure 3.

page 5

FIGURE 3 CLEARANCE AROUND UNIT

t

60” MINIMUM CLEARANCE (2)

60”

MINIMUM

CLEARANCE

(2)

NOTE:

(I)

Minimum vertical clearance above unit should be 10

feet.

(2) Clearance to condenser coil must be increased if more

than one side is obstructed or between adjacent units.
Consult your

McQUAY

sales representative.

Service Access
Each end of the unit must be accessible after installation for peri-

odic service work.

Compressors and manual liquid line shutoff valves

are accessible from the control center end of the unit through re-

movable access panels on unit sizes 089 through 159 and hinged side

access doors on unit sizes 067 and 078.

All operational, safety,

and starting controls are located in the unit control center.

They

are protected by a keylocked,

weatherproof enclosure which contains

internal"dead front"

doors for protection of service personnel from
high voltage starting controls while servicing low voltage opera­tional controls.

All resettable or adjustable controls are located

just below the main control center.

There is one resettable control

enclosure on each side of the unit and each enclosure contains con-

trols for compressors on that side of the unit.

Capped connections

for field service gauges are also located inside these enclosures.
In addition,

each of these enclosures are removable to improve access

to compressors for field replacement.

The condenser fans, motors,

and drives are accessible through a walk-

in,

keylocked access door.

The access door is located at the end of

the unit opposite the control center.

An internal fan guard is located below the condenser fans and drives
on units 089 through 159.

This guard must be removed to service the

fan drives but MUST always be reinstalled when service work is com-

plete.

On unit sizes 067 and 078,

an interlock switch kills power to conden-

ser fans whenever the door is opened for service work on fans or

drives.

CAUTION:

Disconnect all power to the unit while servicing condenser
fan drives.

page

6

Vibration Isolators
Vibration isolators are recommended for all roof mounted installa-

tions or wherever vibration transmission is a consideration.

Table

2 lists spring isolators for all ALP unit sizes.

Figure 4 shows

isolator locations in relation to the unit control center.

Figure 5

gives dimensions that are required to secure each

McQuay

isolator

selection to the mounting surface.
Table 3 shows the isolator loads at each location shown in Figure 4

and the maximum loads for each McQuay selection.

TABLE 2

VIBRATION

ISOLATORS

216404B-27 2164046-26

TABLE 3

IS0 LATOR LOADS

page 7

REFRIGERANT PIPING

General
McQuay type ALP condensing units are adaptable to either chilled

water or air handling air conditioning applications.

The only re­striction on applications is that the evaporator be selected for a
system using refrigerant 22.

Evaporator Above Condensing Unit
Figure 6 shows an installation where the evaporator is installed

above the condensing unit.

It is shown for an air handling instal­lation but all components shown are recommended for chilled water
installations except that a refrigerant distributor is not usually
required for shell-and-tube evaporators.

FIGURE 6

EVAPORATOR ABOVE CONDENSING UNIT

Legend

a

Filter-drier

b

Solenoid valve

:

Sight-glass/moisture indicator
Thermal expansion valve

e

Suction line, pitched toward compressor

f

Liquid line

9

Vibration absorber

Notes:

1. Piping shown is for one circuit only, second circuit is similar.

2. All piping & piping components are by others.

Evaporator Below Condensing Unit
Figure 7 shows an installation where the evaporator is installed be-

low the condensing unit.

It is shown for an air handling installa­tion but all components shown are recommended for chilled water in­stallations except that a refrigerant distributor is not usually re-

quired for shell-and-tube evaporators.

Mote that a double suction

riser is shown for this arrangement.
Risers

"A + B" are sized so that their combined cross-sectional in­ternal area will allow full load unit operation without excessive
pressure drop (see notes, Table 4).

Riser

"B"

is sized to provide

adequate suction gas velocity for proper oil return at minimum load
conditions.

This riser becomes effective only when the trap shown

in riser "A"

fills itself with oil.

It should be emphasized that

the trap shown in riser "A"

should be designed to contain a minimum

internal volume to keep the total system oil requirements at a mini-

mum.

Table 4 gives recommended line sizes for both single and double

suction lines and for liquid lines.

page

9

Figure 9 shows typical field wiring that is required for unit instal-

lation.

Items that require field wiring are:

liquid line solenoids

(SVl & SV2),

optional hot gas bypass solenoid

(SV5)

and the cooling

thermostat as well as the unit power supplies.

FIGURE 9

TYPICAL FIELD WIRING

PBl

DISCONNECT

UNIT MAIN

BY OTHERS--\,,< TERMINAL BLOCK

3pH ---_H

___

POWER

___/-:__

CONI, llNlT

COMPRESSORS

c

AND FAN MOTORS

;BK

SuppLy

_ _

__I’_

-

-

WH

I

\

SEPARATE

II?,“-IOA

LEGEND

POWER FOR CONTROLS

I

‘,‘--

DISCONNECT BY OTHERS

OPTIONAL

FdSEU

i g_ ~~~SLT~OM~~~,~~NNECTION

01

8

A

NOTE

I

TRANSFORMER

FUSE-IO A

0 II

-FLOW SWITCH

(C.W.

SYSTEMS)

irJH_WHlTt

WlhlNG

fNEUT1.

SVl,2-LIOUID ’ INE

SOL. VALVE

REFRIGERANT CIRCUIT I
SAFETY AND OPERATING

SVS-HOT

GAS BY PASS

CONTROLS

SOL VALVE

R3,4-COMP.

384 START

TIME

CLOCK;;-

RELAYS

R5,6,7,E

-SAFETY

RELAYS

PSI.2 -PUMPDOWN

SWITCHES

TDl1,12,13-COMP

SEOUEN-

CING TIME DELAYS

Rx-EVAP. FAN INTERLOCK

PREVENTS OPENING
SV’S WITHOUT LOAD

RELAYS PROVIDE
RECYCLING PUMP

DOWN DURING OFF

SEASON

REFRIGERANT CIRCUIT

2

SAFETY AND OPERATING

CONTROLS

UNIT CONDENSER

FANS

OPERATING CONTROLS

POWER SUPPLY
FOR CONTROLS

’

I

1

I

I

I

PUMP STARTER

PUMP STARTER

CIRCUIT

R9

RIO

NOTE; CIRCUIT SHOWN ASSUMES CONTINUOUS

6

6

T

-C

PUMP

OPERATIIN~FOR

INTERMITTENT

CC. W.

SYSTEMS1

a0 __:

I I

1

PUMP OPERATION CONSULT

McOUAY

I I

I

Thermostat Wiring
Since it is impossible for

McQuay to anticipate the type of installa-

tion that an ALP condensing unit may be used on, we do not factory

install a thermostat.

We do,

however,

provide numbered terminals in-

side the unit control center to which a thermostat may be connected.
These terminals are shown and labeled "Terminals For Thermostat" on
the electrical schematics.

On a two circuit unit it is important to connect the thermostat so
that as successive stages of cooling are called for, the compressors

in the unit will be started to alternately increase the condenser
load from refrigerant circuit 1 to circuit 2.

This is illustrated

in Table 9.

Figure 10 shows how to install 2 independent four stage
thermostats for controlling an 8 stage unit and Figure 11 shows typi­cal field wiring for an 8 stage thermostat.

page 14

Flow Switch for Chilled Water Applications

A WATER FLOW SWITCH MUST BE MOUNTED in either the entering or leav­ing water line to insure that there will be adequate water flow and
cooling load to the evaporator before the unit can start.

This will

safeguard against slugging the compressors on start up.

It also

serves to shut down the unit in the event that water flow is inter­rupted to guard against evaporator freeze up.

A flow switch is available from McQuay under ordering number

860-

175033x-00.

It is a "paddle"

size from 1" to 6" nominal.

type switch and adaptable to any pipe

Certain minimum flow rates are required

to close the switch and are listed in Table 11.

Installation should

be as shown in Figure 13.

TABLE 11

FIGURE 13

FLOW SWITCH MINIMUM FLOW RATES

NOMINAL

MINIMUM REQUIRED

PIPE SIZE

FLOW TO ACTIVATE

(INCHES)

SWITCH

(GPM)

1

6.00

1

l/4

9.80

1

l/2

12.70

2

18.80

2

l/2

24.30

3

30.00

4

39.70

5

58.70

6

79,20

FLOW DIRECTION
MARKED ON SWITCH

1.00 NPT FLOW SWITCH
CONNECTION

G%

O:Nl.,.

AFTER

SWiTCH

BEFORE SWITCH

Electrical connections in the unit control center should be made at
terminals 11 and 12.

The normally open contacts of the flow switch

should be wired between these two terminals.

There is also a set of

normally closed contacts on the switch that could be used for an in­dicator light or an alarm to indicate when a "no flow" condition
exists.

Evaporator Fan Interlock for Air Handler Coil Installations

It is important to interlock the air handler evaporator fan with the
condensing unit control center to insure that there will be a cooling
load on the evaporator before the unit can start, to prevent com­pressor slugging.

A pair of terminals for each refrigerant circuit

is available in the unit control center for this purpose.

These

terminal numbers are shown in Figure 12.

page 18

Control Center

All electrical

controls are enclosed in a weatherproof control cen-

UNIT LAYOUT AND PRINCIPLES OF OPERATION

ter with keylocked,

hinged access doors.

The control center is com-

posed of three separate enclosures.

The upper enclosure is the

largest and contains all of the 208,

230, or 460 volt compressor and

fan motor starting controls.

Also included in this enclosure but

partitioned separately are the exposed terminal type

-

115 volt oper-

ational controls. A "dead front"

cover over the high voltage section

protects service personnel from high voltage starting controls while

servicing low voltage operational controls.

Below the upper enclosure are two smaller,

separate enclosures that

contain 115 volt adjustable or resettable controls.

There is one of

these enclosures on each side of the unit, and each contains controls
for the compressors on that side.

Power supply conduits are intended to come into the bottom of the
upper enclosure and between the two lower enclosures.

It is recom­mended that the unit disconnect switch be mounted away from the unit
but Figure 14 recommends a unit mounting arrangement if the discon-

nect must be unit mounted.

FIGURE 14

POWER CONDUIT ENTRY

CONTROL

~

CENTER

DISCONNECT

Power

into
unit

ALP-089A THRU 159A

ALP

-

067A THR U 078A

page 19

Sequence of Operation
The following sequence of operation is typical for ALP Seasoncon air

cooled condensing unit operation.

It is written for a 4 compressor

unit,

but where components that apply to the fourth compressor are

referred to,

the equivalent components for the third and second com-

pressors are indicated in parentheses.

With the control circuit power on,

control stop switch

Sl

closed,

and manual pumpdown switches

PSl

and PS2 closed ("Auto." position),

115 volt power is applied through control circuit fuse

Fl

to the com-

pressor crankcase heaters

HTRl

through HTR4, (HTR3,

HTR2),

and also

to the contacts of low pressure switches

LPl

and LP2.

When the remote time clock, ambient thermostat, manual shutdown

switch and/or evaporator fan interlocks energize the thermostatic
circuit,

and provided that high pressure controls HP1 and 2 and com-

pressor motor protectors

MPl

through PIP4

(MP3,

MP2) do not sense an

alarm condition,safety relays R5 through R8 (R7,

R6)

are energized

closed applying power to the temperature control thermostat. At this

point the unit will operate automatically in response to the thermo-

stat.

On a call for cooling,

the temperature control thermostat

TCl

ener-

gizes liquid line solenoid valve

SVl,

opening the valve and allowing

refrigerant to flow into the evaporator.

As refrigerant pressure

builds up,

low pressure control

LPl

closes,energizing low pressure

relay

R9

which closes to energize compressor contactor Ml, starting

compressor number 1. Closing relay

R9

contacts also energizes con-

denser fan relay

R17.

Closing its contacts and providing power to

condenser fan motor contactors Mll,12

&

13 on 3 & 4 compressor units,

or

Mll, & 12 on 2 compressor units.

If additional stages of cooling are required, temperature control
thermostat

TCl

energizes liquid line solenoid valve SV2 after time

delay relay

TDll

has sequenced closed,to initiate the same starting

sequence in refrigerant circuit number 2.

On 3 and 4 compressor units,if additional cooling is still required,

the third and fourth stages of temperature control thermostat

TCl
energize the third and fourth compressors after time delay relays
TD12 and TD13 have sequenced closed.

Pumpdown Cycle

As the temperature control thermostat is satisfied, it opens its con-

tacts,

de-energizing liquid line solenoid valve

SVl,

causing the

valve to close. When the compressor has pumped most of the refrig-

erant from the evaporator to the condenser, the low pressure control
LPl

opens,shutting down the compressor and condenser fan motors.

Should a closed solenoid valve allow refrigerant to leak to the low
side of the refrigerant circuit during unit "off" time, the buildup
in pressure will cause the low pressure control to close, energizing
the low pressure relay and starting the compressor for pumpdown.

NOTE:

Models ALP-067AS and 078AS have single refrigerant circuits
but dual pumpdown switches

(PSl &

PS2). To manually pump

these units down,

it is recommended that both pumpdown

switches be moved to the "man.pumpdown" position simultane-

ously.

page 22

START-UP AND SHUT-DOWN

Pre Start--Up

1.

2.

3.

4.

5.

6.

7.

8.

With all electric disconnects open, check

all screw or lug type
electrical connections to be sure they are tight for good elec­trical contact.

fore shipment,

Although all factory connections are tight be-

vibration.

some loosening may have resulted from shipping

a) On chilled water installations,

check to see that all water
piping is properly connected.
b)

Open all water flow valves and start the chilled water pump.
Check all piping for leaks and vent the air from the evaporator
and system piping to obtain clean,

non-corrosive

water in the
evaporator circuit.
Check the compressor oil level.

Prior to start-up, the oil level

should cover at least

l/2

of the oil sight glass.

Remove the

(8)

compressor shipping blocks that are attached to the

compressor rails and the base of the unit.

The ALP 067 and 078

do not have shipping blocks.
Check the voltage of the unit power supply and see that it is

within the

+

10%

tolerance that is allowed.

Phase voltage unbal-

ance must be within

t

2%.

Check the unit power supply wiring for adequte ampacity and a

minimum insulation temperature rating of 75C.
Verify that all mechanical and electrical inspections have been

completed per local codes.
See that all auxiliary control equipment is operative and that
an adequate cooling load is available for initial start up.

Initial Start-Up

1.

Open the compressor suction and discharge shutoff valves until

back seated.

2.

Always replace valve seal caps.
Open the manual liquid line shutoff valve at the outlet of the
subcooler.

3.

Check to see that pumpdown switches

(PSl &

PS2)

are in the

Isman.

pumpdown"

position and the control stop switch

(Sl)

is in the

IIon"

position.

4.

Adjust the dial on the temperature controller to the desired

chilled water or leaving air temperature.

5. Throw the main power and control circuit disconnects to the "on"

position.

CAUTION:

Most relays and terminals in the unit control center are
hot with

Sl

and the control circuit disconnect on.

6.

Allow the crankcase heaters to operate for at least 8 hours prior
to start-up.

7.

Start the auxiliary equipment for the installation.

8.

Start the system by moving pumpdown switches

(PSl &

PS2) to the

"auto.

pumpdown" position.

9.

After system performance has stabilized,

it is necessary that the

"Compressorized Equipment Warranty Form" (form no.

206036A)

be

completed to obtain full warranty benefits.

This form is shipped

with the unit and after completion should be returned to McQuay's

Service Department through your sales representative.

page

37

Temporary Shut-Down

Move pumpdown switches

(PSl &

PS2) to the "man. pumpdown" position.

After the compressors have pumped down,

turn off the chilled water

pump or evaporator fan.

It is especially important on chilled water

installations that the compressors pump down before the water flow

to the evaporator is interrupted to avoid freeze up.
Start-Up After Temporary Shut-Down

1.

Start the chilled water pump or evaporator fan.

2.

With control stop switch

(Sl)

in the

"on"

position, move pumpdown

3.

switches

(PSl &

PS2) to the '"auto. pumpdown" position.

Observe the unit operation for a short time to be sure that the

compressors do not cut out on low oil pressure.

Extended Shut-Down

1.

Close the manual liquid line shutoff valves.

2.

After the compressors have pumped down, turn off the chilled
water pump or evaporator fan.

3.4.Turn off all power to the unit and to the auxiliary equipment.
Move the control stop switch

(Sl)

to the

"off"

position.

5.

Close the compressor suction and discharge valves.

6.

Tag all opened disconnect switches to warn against start up be-

fore opening the compressor suction and discharge valves.

Start-Up After Extended Shut-Down

1.

2.

3.

4.

5.

6.

7.

8.

9.

Inspect all auxiliary equipment (pumps, fans, etc.) to see that
each device is in satisfactory operating condition.
Remove all debris that has collected on the surface of the con-

denser coils.

Open the compressor suction and discharge valves.

Open the manual liquid line shutoff valves.
Check to see that pumpdown switches

(PSl 6;

PS2) are in the "man.
pumpdown" position.
Turn on the electric power to the unit and other parts of the

system.
Allow the crankcase heaters to operate for at least 8 hours prior
to start-up.
On chilled water installations,

start the chilled water pump and

purge the water piping as well as the evaporator.

Check to see that the control stop switch (Sl) is in the

"on"

position.

CAUTION:

Most relays and terminals in the unit control center are
hot with

Sl

and the control circuit disconnect on.

10.

Start the unit by moving pumpdown switches

(PSl &

PS2) to the

"auto.

pumpdown" position.

11.

After running the unit for a short time, check the oil level in

each compressor crankcase and check for flashing in the refri-

gerant sight glass.

page 38

SYSTEM MAINTENANCE

General

On initial start up and periodically during operation it will be

necessary to perform certain routine service checks.

Among these
are checking the compressor oil level and taking condensing, suc­tion and oil pressure readings.

During operation, the oil level

should be visible in the oil sight glass with the compressor run-

ning.

On units ordered with gauges,condensing,suction and oil
pressures can be read from the unit control center. The gauges
are factory installed with a manual shutoff valve on each gauge

line.

The valves should be closed at all times except when gauge
readings are being taken. On units ordered without gauges, the
gauge shutoff valves come factory installed inside the unit control

center for convenient connection of service gauges form outside the

unit.
Fan Shaft Bearings
The fan shaft bearings do not require lubrication at the time the

unit is put into service.

The fan shaft bearings should be greased
once a year using STANDARD OIL COMPANY AMCO Multi-Purpose Lithium
Grease.

DO NOT OVERLUBRICATE.

Fan Motor Bearings

All fan motors are ball bearing,

pre-lubricated and do not require

the addition of grease at the time of installation.

Periodically,

the ball bearings should be cleaned and the grease renewed, to gain

the ultimate in service from the motor bearings.
Extreme care must be exercised to prevent foreign matter from enter-

ing the ball bearings.

It is also important to avoid overgreasing.
Only a high grade clean mineral grease having the following charac­teristics should be used.

Consistency: A little stiffer than that

of Vaseline,maintained over the operating temperature range; melting

point preferably over 150C

(302OF);

freedom from separation of oil
and soap under operating and storage conditions and freedom from a­brasive matter, acid, alkali and moisture.

Specific greasing instructions are to be found on the label attached

to the unit and should be generally followed.
Electrical Terminals
CAUTION:

ELECTRIC SHOCK HAZARD,

TURN OFF ALL POWER BEFORE CONTINU-

ING WITH FOLLOWING SERVICE.

All power electrical terminals should be retightened every 6 months,

as they tend to loosen in service due to normal heating and cooling
at the wire.

Compressor Oil Level
Because of the large refrigerant charge required in an air cooled

condensing unit it is usually necessary to put additional oil into
the system.

The oil level should be watched carefully upon initial

start up and for sometime thereafter.

page 39

At the present time,Suniso

#3GS

oil is the only oil approved by

Copeland for use in these compressors.

The oil level should be main­tained at about the midpoint of the sight glass on the compressor
body.

Condensers

Condensers are air cooled and constructed with

3/8 0-D.

copper tubes

bonded in a staggered pattern into rippled aluminum fins.

No main­tenance is ordinarily required except the occasional removal of dirt
and debris from the outside surface of the fins.

Care should be

taken not to damage the fins during cleaning.

Periodic use of the

purge valve on the condenser will prevent the buildup of non-conden-

sables.
Refrigerant Sight Glass

The refrigerant sight glasses should be observed periodically.

(A

monthly observation should be adequate.)

A clear glass of liquid in-

dicates that there is adequate refrigerant charge in the system to

insure proper feed through the expansion valve.

Bubbling refriger-

ant in the sight glass indicates that the system is short of refri-

gerant charge. On sight glasses ordered from XcQuay as part of the

"Liquid Line Accessory Kits" listed on page 12, an element inside

the sight glass indicates what moisture condition corresponds to a

given element color.

If the sight glass does not indicate a dry con-

dition after a few hours of operation,

the unit should be pumped down

and the cores in the filter-driers changed.

SERVICE

SERVICE ON THIS EQUIPMENT TO BE PERFORMED BY QUALIFIED REFRIGERATION SERVICE PER-

SONNEL. CAUSES FOR REPEATED TRIPPING OF SAFETY CONTROLS MUST BE INVESTIGATED AND

CORRECTED.

Filter-Driers

To change the filter drier core(s)

,

pump the unit down by moving

pumpdown switches

(PSl &

PS2) to the "man. pumpdown" position.

Turn

off all power to the unit and install jumpers from terminals 21 to

24 and 41 to 44.

Turn power to the unit back on and re-start the

unit by moving pumpdown switches

(PSl &

PS2) to the "auto. pumpdown"

position.

Close the manual liquid line shutoff valve(s) and when

evaporator pressure reaches 0 PSIG,

(Sl)

to the "off" position.

move the control stop switch

This will close the liquid line sole-

noid valve(s) and isolate the short section of refrigerant piping

containing the filter-drier(s).

Remove the cover plate from the

filter-drier shell and replace the core(s).

After core replacement,

replace the cover plate.

A leak check a­round the flange of the filter-drier shell is recommended after the
cores have been changed.

page

40

Liquid Line Solenoid Valve
The liquid line solenoid valves,

which are responsible for automatic

pumpdown during normal unit operation,

maintenance.

do not normally require any

They may, however,require replacement of the solenoid

coil or of the entire valve assembly.
The solenoid coil may be removed from the valve body without opening

the refrigerant piping by moving pumpdown switches

(PSl & PS2)

to

the

1'man.

pumpdown" position.

The coil can then be removed from the
valve body by simply removing a nut or snap ring located at the top
of the coil.

The coil can then be slipped off its mounting stud for

replacement.

Be sure to replace the coil on its mounting stud before

returning pumpdown switches

(PSl

&

PS2)

to the "auto. pumpdown" po-

sition.

To replace the entire solenoid valve,

the unit must be pumped down

by use of the manual liquid line shutoff valve.
Thermostatic Expansion Valve

The expansion valve is responsible for allowing the proper amount of
refrigerant to enter the evaporator regardless of cooling load. It
does this by maintaining a constant superheat.

(Superheat is the
difference between refrigerant temperature as it leaves the evapor­ator and the saturation temperature corresponding to the evaporator

pressure.)

Typically,

15F.

superheat should run in the range of

10F

to

On valves purchased through

McQuay,

the superheat setting can
be adjusted by removing a cap at the bottom of the valve to expose
the adjustment screw.

Turn the screw clockwise (when viewed from the
adjustment screw end) to increase the superheat setting and counter­clockwise to reduce superheat.

Allow time for system rebalance af-

ter each superheat adjustment.

INLET

POWER ELEMENT
(CONTAINS DIAPHRAGM)

OUTLET

SPRING

ADJUSTMENT SCREW

CAP

page 41

Trouble Shooting Chart

PROBLEM POSSIBLE CAUSES

POSSIBLE CORRECTIVE STEPS

1. Main switch open.

1.

Close switch.

2. Fuse blown. Circuit breakers open.

2. Check electrical circuits and motor winding for shorts
or grounds. Investigate for possible overloading. Re­place fuse or reset breakers after fault is corrected.

3. Thermal overloads tripped.

3. Overloads are auto. reset. Check unit closely when

Compressor will

unit comes back on

line.

not run

4. Defective contactor or coil. 4. Repair or replace.

5. System shut down by safety devices.

5. Determine type and cause of shutdown and correct it
before resetting safety switch.

6. No cooling required.

6. None. Wait until unit calls for

cooling.

7. Liquid line solenoid will not open. 7. Repair or replace coil.

8. Motor electrical trouble 8. Check motor for opens, short circuit, or burn out.

9. Loose wiring.

9. Check all wire junctions, Tighten all terminal screws.

I.

Flooding of refrrgerant Into crankcase. 1. Check setting of expansion valve.
Compressor noisy 2. Improper piping support on suction or 2. Relocate, add or remove hangers.
or vibrating liquid line.

3. Worn compressor

3. Replace.

1.

Non-condensibles in system.

I.

Purge the non-condensibles.

High Discharge

2. System overcharged with refrigerant.

2. Remove excess.

Pressure

3. Discharge shut off valve partially closed.

3. Open valve.

4. Seasontrol out of adjustment 4. Adjust Seasontrot valves.

5. Fan not running.

5. Check belts and electrical

crrcuit.

I.

Faulty condenser temperature regulation.

I.

Check condenser control operation.

2. Suction shut-off valve partially closed.

2. Open valve.

Low Discharge

3. insufficient refrrgerant in system.

3. Check for leaks. Repair and add charge.

Pressure

4. Low suction pressure.

4. See Corrective Steps for low suction pressure below.

5. Compressor operating unloaded. 5. See Corrective Steps for failure of compressor to load
up below.

1. Excessive load.

1.

Reduce load or add additional equipment.

High Suction 2.

Expansron

valve

overfeedrng.

2. Check remote bulb. Regulate superheat.

Pressure

3. Compressor unloaders open.

3. See Corrective Steps below for failure of compressor
to load up.

1. Lack of refrigerant.

1.

Check for leaks. Repair and add charge.

2. Evaporator dirty. Plugged

acr

filters.

2. Clean

chemrcally.

3. Clogged

liqurd lrne

filterdrier.

3. Replace cartridge(s).

Low Suction

4. Clogged suction line or compressor suction. 4. Clean

strarners.

Pressure

gas strainers.

5. Expansion valve malfunctioning.

5. Check and reset for proper superheat.

6. Condensing temperature too low.

6. Check means for regulating condensing temperature.

7. Compressor will not unload. 7. See

Correctrve Steps for failure of compressor to

unload.

Compressor will not 1. Defective

capacrty

control.

I.

Replace.

unload or load up. 2. Pressurestat not set for application. 2. Reset pressurestat setting to fit applicatron.

1. Clogged suction oil strainer.

1. Clean.

2. Excessive liquid

rn

crankcase.

2. Check crankcase heater. Reset expansion valve for
higher superheat. Check liquid line solenoid valve

operation.

3. Oil pressure gauge defective.

3. Repair or replace. Keep valve closed except when
taking readings.

Little or no oil

4. Low oil pressure safety switch defective.

4. Replace.

pressure

5. Worn

011

pump.

5. Replace.

6. Oil pump reversing gear stuck in wrong

6. Reverse

drrectron

of compressor rotation.

position.

7. Worn

bearrngs.

7. Replace compressor.

8. Low oil level.

8. Add oil.

9. Loose fitting on oil lines.

9. Check and tighten system.

10. Pump housing gasket leaks.

10. Replace gasket.

11. Flooding of refrigerant into crankcase.

11. Adjust thermal expansion valve.

Compressor loses

1. Lack of refrrgerant.

1.

Check for leaks and repair Add refrigerant.

oil

2. Excessive compression ring blow-by.

2. Replace compressor.

1. Low voltage during high load conditions.

1. Check supply voltage for excessive

lrne

drip.

2. Defective or grounded wring in motor.

2. Replace compressor motor.

3. Loose power wiring.

Motor overload

3. Check all connections and tighten.

4. High

condensrng

temperature.

4. See Corrective Steps for high discharge pressure.

relays or circuit

5. Power line fault causing unbalanced voltage.

5. Check supply voltage. Notify power compnay. Do not

breakers open

start until fault is corrected.

6. High ambient temperature around the

over-

6. Provide ventilation to reduce heat.

load relay.

7. Failure of second starter to pull in on

part-

7. Repair or replace starter or time delay mechanism.

winding start systems.

Compressor thermal
protector switch
open.

1. Operating beyond design conditions.

2. Discharge valve partially shut.

3. Blown valve plate gasket.

I. Add facilities so that conditions are within allowable

limits.

2. Open valve.

3. Replace gasket.

page 42

IN-WARRANTY RETURN MATERIAL PROCEDURE

Compressor

Copeland Refrigeration Corporation has stocking wholesalers who main­tain a stock of replacement compressors and service parts to serve

refrigeration contractors and servicemen.

When a compressor fails in warranty,

contact your local sales represen-

tative,

or McQuay Warranty Claims Department at the address on the
cover of this bulletin. You will be authorized to exchange the de­fective compressor at a Copeland Wholesaler,or an advance replace­ment can be obtained. A salvage credit is issued to you by the whole-

saler on the returned compressor after Copeland factory inspection of
the inoperative compressor. Provide McQuay with full details and in­voices and we

will

reimburse the difference.

In this transaction, be

certain that the compressor is definitely defective.

If a compressor

is received from the field that tests satisfactorily, a service charge
plus a transportation charge will be charged against its original cre­dit value.

On all out-of-warranty compressor failures,

Copeland offers the same

field facilities for service and/or replacement as described above.
The credit issued by Copeland on

the returned compressor will be deter-

mined by the repair charge established for that particular unit.
Components Other Than Compressors

Material may not be returned except by permission of authorized fac-

tory service personnel of McQuay, Inc., at Mpls., MN. A "Return
Goods"

tag will be sent to be included with the returned material.
Enter the information as called for on the tag in order to expedite
handling at our factories and prompt issuance of credits.

The return of the part does not constitute an order for replacement.
Therefore,

a purchase order must be entered through your nearest
McQUAY Representative. The order should include part name, part num­ber,

model number and serial number of the unit involved.

Following our personal inspection of the returned part, and if it is
determined that the failure is due to faulty material or workmanship,
and in warranty,credit will be issued on customer's purchase order.

All parts shall be returned to the pre-designated McQUAY factory,

transportation charges prepaid.

APPENDIX

STANDARD CONTROLS

Oil Pressure Safety Control
The oil pressure safety control is a manually resettable device which

senses the differential between oil pressure at the discharge of the
compressor oil pump and suction pressure inside the compressor crank­case.

When the oil pressure reaches approximately 15 PSI above the

crankcase suction pressure,

the pressure actuated contact of the con-

trol opens from its normally closed position.

If this pressure dif­ferential cannot be developed,the contact will remain closed and
energize

a heater element within the control.

The heater element
warms a normally closed bimetallic contact and causes the contact to
open de-energizing a safety relay and breaking power to the compres­sor.

page 43

It takes about 120 seconds to warm the heater element enough to open
the bimetallic contact thus allowing time for the pressure differen­tial to develop.

If during operation,the differential drops below 10 PSI, the heater
element will be energized and the compressor will stop.

The control
can be reset by pushing the reset button on the control. If the com­pressor does not re-start,allow a few minutes for the heater element

and bimetallic contacts to cool and reset the control again.
To check the control,

pump down and shutoff all power to the unit.
Remove the compressor fuses,and install a voltmeter between termin­als

"L"

and

"M"

of the oil pressure control.

Turn on power to the

unit control circuit (separate disconnect or main unit disconnect de-

pending on the type of installation).

Check to see that the control

stop switch

(Sl)

is in the "on" position.

The control circuit

should now be energized but with the absence of the compressor fuses,

__

no oil pressure differential can develop and thus the pressure actu­ated contacts of the control will energize the heater element and
open the bimetallic contacts of the control within 120 seconds.

When

this happens,the safety relay is de-energized, the voltmeter read-

ing will rise to

115V,

and the compressor contactor should open. Re-

peated operations of the control will cause a slight heat buildup

in the bimetallic contacts resulting in a slightly longer time for

reset with each successive operation.

LINE (SEE NOTE

1)

NEUTRAL

-

HEATER ELEMENT

CONTACT

L

M

LINE (SEE NOTE 2)

41

NEUTRAL

BIMETALLIC CONTACTS

SAFETY RELAY

NOTES:

1. Hot only when the unit thermostat calls for compressor
to run.

2. Hot only when other safety control contacts are closed.

High Pressure Control

The high pressure control is a single pole pressure activated switch
that opens on a pressure rise to de-energize the entire control cir­cuit except for compressor crankcase heaters.

It senses condenser
pressure and is factory set to open at 380 PSIG and can be manually
reset closed at 315 PSIG.

To check the control, either block off

condenser surface or start the unit with fuses in only one fan fuse

block

(FBll)

and observe the cut-out point of the control by watch-

ing condenser pressure rise.

The highest point reached before cut­out is the cut-out setting of the control.
CAUTION:

Although there is an additional pressure relief device in
the system set at 425 PSIG,

it is highly recommended that

the

"control

stop"

switch

(Sl)

be close at hand in case

the high pressure control should malfunction.

page 44

Low Pressure Control

The low pressure control is a single pole pressure switch that closes
on a pressure rise.

It senses evaporator pressure and is factory set

to close at 60 PSIG and automatically open at 25 PSIG.

The control

has an adjustable range of 20 in. of Hg.

to 100 PSIG and an adjusta-

ble differential of 6 to 40 PSIG.

To check the control (unit must

be running),

move the pumpdown

switch(es) (PSl

and PS2) to the "man.

pumpdown" position.

As the compressor pumps down condenser pressure

will rise and evaporator pressure will drop.

The lowest evaporator
pressure reached before cut-out is the cut-out setting of the control.
By moving the pumpdown

switch(es) (PSl

and PS2) to the "auto. pump-

down"

position,

evaporator pressure will rise.

The highest evapora-

tor pressure reached before compressor re-start is the cut in setting
of the control.

Fantrol

-

Head Pressure Control

--

Fantrol is a system for progressively turning on or off condenser

fans when they are no longer required.

This isdone to reduce con-

denser capacity (typically in low outdoor ambient temperatures) and
is accomplished by a combination of pressure and temperature actuated
controls.

The first fan (No.

11) is started by its contactor when

the first compressor in the unit starts.

The second fan (No. 12) is

controlled by a pair of parallel wired pressure switches, one of

which senses condenser pressure in refrigerant circuit No. 1, and

one which senses pressure in refrigerant circuit No. 2.

The third

fan (No.

13-3 fan units only) is controlled by a pair of parallel

wired temperature switches,

one of which senses condenser air inlet
temperature for refrigerant circuit No. 1 and one for circuit No. 2.
Pressure temperature control set points are indicated below.

j:::_ll

WITH COMPRESSOR WITH COMPRESSOR

To check the cut-in points of the controls,

the unit must initially

be off.

With the unit prepared for start up according to the proce-

dures outlined in this bulletin,

move pumpdown switches

(PSl &

PS2)

to the "auto. pumpdown" position.

Evaporator pressure will begin to

rise and the compressor(s) should start with fan No. 11 starting im-

mediately.

After the compressor(s) starts,

observe condenser pres-

sure as it rises.

When the condenser pressure reaches approximately

270 PSIG, contactor Ml2 should pull in to start fan No. 12.

On 3

fan units, fan No.

13 should start via contactor Ml3 whenever the

ambient air at the condenser inlet reaches 80F.
It may be difficult to check the cut-out point of fan No. 13 (on 3

fan units) at the instant it happens, but it should be off whenever
the ambient air at the condenser inlet is below 70F.

To check the

cut-out point of fan No. 12,

some means of reducing the load on the

unit must be available or the fan operation and condenser pressure(s)

must be observed as the load drops off naturally.

When the condenser

pressure drops to approximately 170 PSIG,

contactor Ml2 should drop

out to turn off fan No. 12.

page 45

OPTIONAL CONTROLS
Dampertrol

-

Optional Head Pressure Control

Dampertrol is an optional system for reducing condenser capacity. It

consists of an assembly of damper blades,

linkages and blade operators

installed over the first fan turned on by Fantrol (Fan No. 11) and

arranged to operate as shown.

The blade operators sense condenser

pressure and extend or contract in response to the pressure to open

or close the damper blades as required to maintain adequate conden­ser pressure.

The operators are factory set to begin opening the

damper blades at 170

+

5 PSIG and to be fully open at 250 2 10 PSIG.

To check the damper blade operator pressure settings, the unit should
be started with the fuses removed from fans

11

and 13 (on 3 fan units

only).

At condenser pressures below 170 & 5 PSIG, the damper blades

should be completely closed.

As pressure rises above 170

&

5 PSIG,

the damper blades should begin opening and be fully open at 250

+_

10 PSIG.

Leaving the fuses in on fan 12 will prevent head pressure

from becoming excessive since this fan will start after the fully

open setting of the damper operators has been observed.

DAMPERTROL IN OPEN POSITION

/DAMPER

SECTION

1

/-

UNIT CONDENSER

DAMPER SECTION

-

rtz3qf

UNIT CONDENSER

DAMPERTROL IN CLOSED POSITION

page 46

Part Winding Start

-

Optional

Part winding start is available on all voltage units and consists of

a solid state time delay wired in series with the contactor that ener-

gizes the 2nd winding of each compressor motor.

Its purpose is to

limit current in-rush to the compressors upon start up.

As each com-

pressor starts,

the contactor for the first motor winding is energized
instantly while that for the second motor winding is delayed for 1
second.

Control checkout is best accomplished by observation as each contac-

tor is pulled in to see that the 1 second delay occurs before the
second contactor pulls in.

LINE

NEUTRAL

PART WINDING
TIME DELAY

1

COMPRESSOR CONTACTOR

(1st

MOTOR WINDING)

LINE

.-%..,

NEUTRAL

A-

COMPRESSOR CONTACTOR

(2nd MOTOR WINDING)

Low Ambient Start - Optional
Low ambient start is available on all units as an option with Fantrol

and included automatically with optional Dampertrol.

It consists of
a solid state normally closed time delay wired in series with a relay.
These are both wired in parallel to the liquid line solenoid valve so
that when the solenoid valve is energized by the unit thermostat, the
low ambient start relay is also energized through the time delay.
The relay has contacts that essentially short circuit the low pres­sure control and allow the compressor to start with the low pressure
control open.

After about 2

3/4

minutes,

the time delay will open and de-energize

the relay.

If the system has not built up enough evaporator pressure

to close the low pressure control,

the compressor will stop.

The

time delay can be reset to its original normally closed position by

moving the pumpdown

switch(es) (PSl

or PS2) to the "man. pumpdown"

position.

Moving the pumpdown switch back to the "auto. pumpdown"
position will again energize the relay for another attempt at start
up

.

If the system has built up enough evaporator pressure, the com-

pressor will continue to run.

To check the control,

turn off all power to the unit and remove the

wire(s) (No.

113

&

213) leading to the low pressure control(s)

(LPl

&

LP2) from terminal 4 in the unit control center.

Remove the com-

pressor fuses and jumper across terminals L & M of the freeze con­trols(s) and oil pressure safety control(s).

Energize the control

circuit by turning on the control circuit disconnect or main power
disconnect (depending on the installation) and the control stop

switch

Sl.

The compressor contactors should pull in instantly.

page 47

NOTE: Line is only hot when the unit thermostat calls for compressor to run.

Compressor Lockout - Optional
Compressor lockout consists of a solid state time delay wired in

series with the compressor contactor(

Its purpose is to prevent

rapid compressor cycling when cooling demands are erratic.

The cir-

cuit illustrated above is for the lead compressor in each refriger­and circuit.

The circuit for the second compressor(s) performs the

same function but is wired differently (see unit wiring diagram).

When the unit thermostat no longer calls for cooling and the com-

pressor contactor have opened,

the lockout time delay breaks open

the circuit preventing compressore re-start.

The circuit remains open for a period of 5 minutes so that if the

unit thermostat should call for cooling before the delay period has
expired,

the compressor will not re-start.

After 5 minutes, the

time delay will close its contacts to complete the circuit and be
ready for start up.

The time delay opens its contacts whenever pow­er to terminal 4 is interrupted and resets closed automatically af­ter the time delay period.

To check the control,

the compressor(s) must be running initially.

Move the pumpdown switch

(PSl

or

PS2)

to the "man. pumpdown" posi-

tion.

Immediately after the compressor(s) have stopped running,

move the pumpdown switch back to the "auto. pumpdown" position.

The

lead compressor should not re-start for 5 minutes.

The second com-

pressor in the refrigerant circuit should start approximately 20

seconds after the lead compressor,
high enough to require it.

provided that the cooling load is

the same way.

Each refrigerant circuit can be checked

LINE

(SEE NOTE)

-

’

’

COMF!

LOCKOUT

TIME DELAY

x-k-

TO UNIT THERMOSTAT

NOTE:

Hot whenever freeze control and high

pressure control permit safe operation.

page 48

Alarm Bell - Optional

The 24 volt alarm bell is mounted inside the control center but not

wired to the control circuit.

It is expected that in most cases,
the customer will want to relocate the bell where it will be more
easily heard in the event of a safety failure.

There are leads for
connection of the bell inside a junction box which is located in the
unit control center.

All that is necessary is that the bell be

mounted in a preferred location and wired to the leads in the junc-

tion box.
The bell is wired into the control circuit so that it will sound

whenever there is a failure due to low oil pressure, motor overload,

or excessive condenser pressure.
Hot Gas Bypass

-

Optional

Hot gas bypass is a system for maintaining evaporator pressure at or

above a minimum value.

The purpose for doing this is to keep the ve­locity of the refrigerant as it passes through the evaporator high
enough for proper oil return to the compressor when cooling load con­ditions are light.

The system usually consists of a solenoid valve piped in series with
a pressure regulating valve as shown. Units are available with op­tional hot gas connection with a manual shutoff valve and capped stub.

A hot gas bypass kit consisting of a 115 volt solenoid valve and a

pressure regulating valve is available from McQuay under ordering
number 886-321262B-02 for ALP units 067AS/D through 159AD.

The solenoid valve should be wired to open whenever the unit

thermo-

stat calls for the first stage of cooling (see Figure 10).

The pres-

sure regulating valve that McQuay offers is factory set to begin

opening at 58 PSIG

(32F

for R-22) when the air charged bulb is in

an 80F ambient temperature.

The bulb can be mounted anywhere as

long as it senses a fairly constant temperature at various load con-

ditions.

The compressor suction line is one such mounting location.

It is generally in the 50F to 60F range.

The chart on page 50 indicates

that when the bulb is sensing 50F to 60F temperatures, the valve will

begin opening at 54 to 56 PSIG.

This setting can be changed as in­dicated above, by changing the pressure of the air charge in the
adjustable bulb.

To raise the pressure setting, remove the cap on

the bulb and turn the adjustment screw clockwise.

To lower the set-

ting,

turn the screw counter-clockwise.

Do not force the adjustment
beyond the range it is designed for as this will damage the adjust­ment assembly.

The regulating valve opening point can be determined by slowly reduc-

ing the system load while observing the suction pressure.

When the

bypass valve starts to open,

the refrigerant line on the evaporator

side of the valve will begin to feel warm to the touch.

CAUTION:

The hot gas line may become hot enough to cause injury in

a very short time so care should be taken during valve
checkout.

page 49

On installations where the condensing unit is remote from the evapor­ator,

it is recommended that the hot gas bypass valve be mounted near
the condensing unit to minimize the amount of refrigerant that will
condense in the hot gas line during periods when hot gas bypass is
not required.

The expansion valve,

like the solenoid valve, should not normally re-

quire replacement, but if it does,

the unit must be pumped down by

using the manual liquid line shutoff valve.

If the problem can be

traced to the power element only,

it can be unscrewed from the valve

body without removing the valve but only after pumping the unit down

with the manual liquid line shutoff valves.

HOT GAS BYPASS PIPING

Hot Gas Bypass

Solenoid Valve

DIAGRAM

HOT GAS BYPASS ADJUSTMENT RANGE

REMOTE

BULB

ADJUSTMENT RANGE

a0

I

I I

I

I

I

I

r

SuctionsLine

;,

L

Discharge

Line

Remote Bulb

External Equalizer
Connection to Suction

Side of Evapoator

Bypass Valve

Inlet After
Expansion Valve

TEMP

ioFI

AT BULB LOCATION

page 50