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7 condenser coil performance diagnosis, 8 outdoor unit amp draw diagnosis, 9 cooling capacity diagnosis – Fieldpiece HG3 - Wireless HVAC Guide System Analyzer User Manual

Page 36: 10 heat pump in heating diagnosis

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5.602 Probable oversized metering orifice, consult manufac-

turer’s specifications:

The metering orifice lets too much refriger-

ant through. Check that the orifice is sized properly. Find the metering

device part number and obtain the orifice size from the manufacturer or

distributor and verify the size is appropriate for the air conditioner.

5.603 Check TXV to ensure proper functioning:

This TXV is

not maintaining proper superheat. Check that the TXV bulb is adjusted

properly and in continuous contact with the suction line and well

insulated from the surrounding air.

5.604 Possible liquid line restriction, check liquid line:

Make

sure the service shut-off valves are open. Check the liquid line for kinks,

tight bends or sections that may have been stepped on or crushed.

Check for a large temperature difference between the liquid line at the

compressor and at the metering device.

5.7 Condenser Coil Performance Diagnosis

5.701 Condenser airflow OK:

The condenser airflow and capacity in-

dications are OK.

5.702 Condenser approach unknown, check condenser ap-

proach:

Liquid line temperature and liquid line pressure measurements

need to be taken for the condenser approach. These measurements give

indications of the performance of the air conditioner including diagno-

ses of compressor problems, low capacity, and low condenser airflow.

5.703 Low condenser airflow, clean condenser, check con-

denser fan:

There is insufficient airflow going across the condenser

for the needed heat transfer. Check that the condenser coils and fins

are clean, aligned and free of nearby obstructions. Check the fan motor

bearings to ensure that the fan is rotating freely.

5.8 Outdoor Unit Amp Draw Diagnosis

5.801 Outdoor amp draw OK:

The outdoor unit is running at the

proper amperage for the current conditions.

5.802 Condensing unit amps unknown, check condensing

unit amps:

The outdoor unit amp draw was not measured.

5.803 High outdoor amp draw, probable excessive compres-

sor friction:

Check other possible causes of high amp draw (low con-

denser airflow and refrigerant overcharge) before condemning the com-

pressor. Check that condenser coils and fins are clean, aligned, and free

of nearby obstructions.

5.804 Low outdoor amp draw, possible compressor valve or

motor problem:

Check the refrigerant charge before condemning

the compressor.

5.9 Cooling Capacity Diagnosis

The heat rejection at the outside unit is another measurement that gives

indication of the health of the compressor as well as other potential problems.

5.902 Low capacity:

This unit is operating under its expected capacity.

Check the refrigerant charge, repair if needed, and retest.

5.903 Low capacity, check compressor amps and coil satura-

tion temperatures:

Full diagnosis of this situation requires a com-

plete set of data including compressor amps, high and low side pressures,

and liquid and suction line temperatures.

5.10 Heat Pump in Heating Diagnosis

5.1001 Heating Capacity OK:

The heat pump is delivering the proper

heating.

5.1002 Capacity unknown, check capacity:

The TrueFlow® inputs,

outdoor unit entering temp, return plenum temperature, and supply ple-

num temperature need to be measured before determining capacity.