Fieldpiece ASX14 User Manual

AUTO-

OFF

T/C
Cal

STABLE

Pressure

Temp

SH or SC

ON

LOBATT

Air
Conditioner
Superheat
and Subcooling

ENGLISH

METRIC

R22

R410A

Set
ATM

ASX14

SH

SC

Superheat and
Subcooling Head for
R22 and R410A

with pipe clamp
thermocouple

Model: ASX14

OPERATOR’S MANUAL

Description

The model ASX14 superheat and subcooling
accessory head measures refrigerant pressure and
temperature simultaneously. It then calculates and
displays superheat or subcooling. It has a 1/4”
industry standard fitting for actual pressure. A pipe
clamp thermocouple is included for temperature.
Select R22 or R410A. Select superheat or subcool­ing.Select english or metric units.

Use it your way

EHDL1 AHDL1 w/ Meter DL3 HS30

How to use

1. Connect to COM and Volts jack. Slide ASX14
superheat head onto Fieldpiece "stick" meter,
data logger, electronic handle or connect to
most other meters using Fieldpiece ADLS2
deluxe test leads or AHDL1 handle.

2. Set meter to mVDC range.

3. Calibrate if needed (see Field calibration)

4. Hand tighten 1/4” flare to suction line or liquid
line as close to the evaporator or condenser as
possible using an EPA approved service hose
(not included).

5. Select superheat or subcooling, refrigerant (R22
or R410A) and units (English or metric).

6. Connect the pipe clamp to the suction (super­heat) or liquid (subcooling) line at least six inch­es from the condenser and slide it under the
insulation for best accuracy isolating the pipe
clamp from the ambient air (pg. 2).

7. Select parameter to display (superheat, sub­cooling, pressure, or temperature).

8. You must wait until the system you are testing
has stabilized. The STABLE LED lights when
the reading is stable.

9. Disable Auto-off to data log any of the above
parameters with the DL3 data logger.

10. Once you have the superheat or subcooling
reading follow the manufacturer of the air condi­tioner’s specifications to properly charge or
diagnose the system.

Field calibration

Temperature: To calibrate the system (ASX14,
pipe clamp thermocouple, meter), adjust the cali­bration pot underneath the rubber covering while
measuring a known temperature. Ice water is 32°F
(0°C) and is readily available.

1. Stabilize (by repeated stirring) a large cup of ice

water.

2. Select temperature on ASX14, plug in the pipe

clamp thermocouple and then immerse entire

clamp into the ice water (keep stirring).

3. Adjust the calibration pot to read 32.0 (0.0 if

using °C) on the DMM for optimum accuracy at

room temp.

Pressure: The pressure/vacuum reading prior to
connecting to an A/C system should always be
zero. If you see that you’re getting pressure read­ings of something other than zero without your serv­ice hose attached, you need to set atmospheric
pressure before connecting the ASX14 to the sys­tem. To set atmospheric pressure, press the button
underneath the rubber covering entitled “Set ATM”.
You usually have to set atmospheric pressure each
time you dramatically change elevations. For exam­ple, if you “Set ATM” in Denver and take a pressure
reading of an A/C system in Los Angeles, the pres­sure reading in Los Angeles will be lower than it
actually is.

OFF

2000

AUTO­OFF

T/C
Cal

STABLE

Pressure

Temp

SHor SC

ON

LOBATT

Air
Conditioner
Superheat
andSubcooling

ENGLISH

METRIC

R22

R410A

Set
ATM

ASX14

SH

SC

AUTO­OFF

T/C
Cal

STABLE

Pressure

Temp

SHor SC

ON

LOBATT

Air
Conditioner
Superheat
andSubcooling

ENGLISH

METRIC

R22

R410A

Set
ATM

ASX14

SH

SC

AUTO­OFF

T/C
Cal

STABLE

Pressure

Temp

SHor SC

ON

LOBATT

Air
Conditioner
Superheat
andSubcooling

ENGLISH

METRIC

R22

R410A

Set
ATM

ASX14

SH

SC

AUTO­OFF

T/C
Cal

STABLE

Pressure

Temp

SHor SC

ON

LOBATT

Air
Conditioner
Superheat
andSubcooling

ENGLISH

METRIC

R22

R410A

Set
ATM

ASX14

SH

SC

SPECIFICATIONS

Operating environment: 32ºF to 122ºF; 0ºC to

50ºC at <75%RH

Allow ~5 min. for ASX14 to come to ambient temp.

Storage environment: -4ºF to 140ºF; -20ºC to

60ºC at <80%RH with battery removed.

Battery life: 25 hours typical. No measurable

current draw when in "off" position.

Low battery indication: Red LED lights
Battery: 9V
Auto off: Approx. 15 minutes
Overloads: The ASX14 outputs 3.4V when tem-

perature or pressure is outside of their working
range (overloaded). For ranges below
3400mVDC, the normal overload symbol will be
displayed on the meter (“OL”). For ranges
above 3400mVDC, reading displayed will be
approximately 3.4VDC.

Stated Accuracy: at 73°F ± 9°F (23°C ±5°C) ,

<90% R.H.

Temperature

Range (temperature): -40ºF to 400ºF;

-40ºC to 204ºC

Resolutions: 0.1º
Sensor type: k-type thermocouple
Pipe clamp thermocouple accuracy: ±4ºF

(±2°C) or ±0.75%, whichever is greater, -30ºF to
200ºF (-34°C to 93°C)

System accuracy: ±1ºF;±0.06ºC @ 73ºF ± 5ºF

after ice water calibration (see Field calibration).

Pressure and vacuum

Working range (pressure):

0 to 500 psi; 0 to 4000 kPa

Max displayed pressure: 800psi (5500 kPa)
Working range (vacuum):

29”Hg vac. to 0; 74cmHg vac. to 0

Vacuum will show up as negative value on meter.

Resolutions: 0.1psi or kPa, 0.1”Hg or cmHg vac.
Accuracy:

0 to 200 psig, ±1 psi, 0 to 1378 kPa ±6.9 kPa;
200 to 500 psig, 0.3% ±1 psi, 1378 to 3447 kPa

0.3% ±6.9kPa

Sensor breakdown pressure: 800psi (5500 kPa)

Superheat

Range (temperature): 0ºF to 80ºF; 0ºC to 27ºC
Resolutions: 0.1º
System Accuracy: ±1ºF @ 73ºF ± 5ºF (±0.06ºC

@ 23°C ±3°C) after calibration (see Field cali­bration).

Subcooling

Range (temperature): 0ºF to 80ºF; 0ºC to 27ºC
Resolutions: 0.1º
System Accuracy: ±1ºF @ 73ºF ± 5ºF (±0.06ºC

@ 23°C ±3°C) after calibration (see Field cali­bration).

Warranty

The ASX14, Superheat and Subcooling accesso­ry head is warranted against manufacturer’s defects
for one year. This warranty does not apply to
defects resulting from abuse, neglect, accident,
unauthorized repair, alteration, or unreasonable use
of the instrument. Any implied warranty arising out
of the sale of Fieldpiece's products including but not
limited to implied warranties of merchantability, and
fitness for purpose, are limited to the above.
Fieldpiece shall not be liable for incidental or con­sequential damages.

Service

Return any defective ASX14 to Fieldpiece for
warranty service along with proof of purchase.
Contact Fieldpiece for out of warranty repair
charges.

.

v07

*These charts are an example of a generic

superheat charts for a typical fixed orifice, split res­idential system. These charts should not be used
for charging. A typical manufacturer’s recommend­ed subcooling is 12°F (7°C). These are only exam­ples of what the manufacturer’s may recommend.
Heed all manufacturer’s indications, instructions
and warnings above those in this manual.

The indoor wet bulb measurement can be
accomplished by a Fieldpiece ARH4 or ATWB1 and
should be taken as close to the evaporator coil inlet
as possible. The outdoor dry bulb reading can be
taken with an ARH4, ATB1, ATA1 or any other
Fieldpiece air thermocouple and should be taken as
close to the condenser air inlet as possible.

Measuring actual superheat and
subcooling

Superheat is the difference between the actual
temperature of the refrigerant (gas) as it leaves the
evaporator and the boiling point temperature of the
refrigerant in the evaporator coil. After boiling, the
refrigerant continues to warm up. The number of
degrees it “warmed up” after boiling is called the
superheat. Under worst case conditions (low load
for fixed orifice systems), the refrigerant in the evap­orator boils off near the end of the evaporator coil.
To make sure liquid doesn’t enter the compressor
under the worst case condition (low load), the AC
manufacturers publish charts indicating what the
superheat should be at a given indoor wet bulb
measurement and outdoor air temperature.

Measuring superheat is your best indication on a
fixed orifice system of the proper refrigerant charge
and operating conditions. If everything else is work­ing properly and the actual superheat is too high,
add refrigerant. If it’s too low, remove refrigerant.

Subcooling is the difference between the boiling
point of the refrigerant in the condenser and the
actual temperature of the refrigerant as it leaves
the condenser. The degrees that the refrigerant
“cools down” below the boiling point is the sub­cooling. Under worst case scenario (low load for
TXV) the subcooling will continue to rise. If the
subcooling rises to high, liquid may be backed into

the compressor causing damage and catastrophic
failure.

On TXV systems, subcooling is the best indica­tion of the state of charge in the refrigerant system
since these systems are designed to maintain con­stant superheat.

Properly charging a system ensures maximum

efficiency and longer equipment life.

The hose must have a schraeder valve depress­er on one end to release the refrigerant from the
suction or liquid line. This is the same type of hose
available with most pressure gauge sets. We sug­gest EPA sanctioned “no leak” hoses.

Exercise caution whenever working with any
electricity and high pressure liquid or gas. Follow all
instructions provided with equipment being serviced
or installed.

Target superheat and subcooling

Heed all equipment manufacturer’s specifica­tions, warnings and suggestions above anything
found in this manual.

To determine the target superheat (fixed orifice
system) or subcooling (charts vary dramatically
from one system to another), you will typically need
three things. Outdoor dry bulb (outdoor air temper­ature), indoor wet bulb, and the manufacturers tar­get superheat chart or subcooling chart.

You can use the ARH4 Fieldpiece accessory

head for both indoor wet bulb and outdoor dry bulb.
Or you can use any Fieldpiece meter that has a
temperature function along with a ATWB1 wet bulb
thermocouple. Below is a diagram of the ASX14 on
a split-system residential A/C unit.

Condenser

Evaporator

Compressor

Throttle Valve (TXV, Cap tube, Fixed Oriffice)

Outside

Indoor

Liquid

Vapor and Liquid

Vapor

Liquid

Vapor

Vapor and Liquid

Liquid

Vapor

Outside

Indoor

AUTO­OFF

T/C
Cal

STABLE

Pressure

Temp

SHorSC

ON

LOBATT

Air
Conditioner
Superheat
andSubcooling

ENGLISH

METRIC

R22

R410A

Set
ATM

ASX14

SH

SC

AUTO­OFF

T/C
Cal

STABLE

Pressure

Temp

SHorSC

ON

LOBATT

Air
Conditioner
Superheat
andSubcooling

ENGLISH

METRIC

R22

R410A

Set
ATM

ASX14

SH

SC

Checking
Subcooling
Using the
ASX14

Checking
Superheat
Using the
ASX14

R

e

f

r

i

g

e

r
a

n

t

F

l

o

w

R

e

f

r

i

g

e

r

a

n

t

F

l

o

w

Generic Target Superheat Charts*