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DIAGNOSTICS
Service Analyzer Charts
COMPRESSOR OVERHEATING
SYMPTOM
High superheat
(greater than 15°F
[-9°C] at coil)
Low line voltage
High line voltage
High head
pressure
Short cycling of com-
pressor
42
POSSIBLE CAUSE
Low charge
Faulty metering device
High internal load
Restriction in liquid line
Low head pressure
Suction or liquid line subjected to high heat
source
Loose wire connections
Power company problem, transformer
Undersized wire feeding unit
Power company problem
Overcharge
Dirty heat pump coil
Faulty or wrong size heat pump fan motor
Faulty fan blade or wrong rotation
Recirculation of air
Additional heat source
Noncondensibles
Equipment not matched
Faulty pressure control
Loose wiring
Thermostat
TEV
Distributor tube
CHECK/REMEDY
Check system charge�
Restricted cap tube, TEV (TXV)
Power element superheat out of adjustment internally
Foreign matter stopping flow
Hot air (attic) entering return
Heat source on; miswired or faulty control
Drier plugged�
Line kinked�
Low charge
Operating in low ambient temperatures
Hot attic
Hot water line
Check wiring�
Have problem corrected before diagnosis continues�
Correct and complete diagnosis�
Have problem corrected�
Check system charge�
Clean coil�
Replace fan motor�
Replace fan blade�
Replace with correct rotation motor�
Correct installation�
Check for dryer vent near unit�
Check for recirculation from other equipment�
Recover refrigerant� Evacuate and recharge system�
Correct mismatch�
Replace pressure control�
Check unit wiring�
Located in supply air stream
Differential setting too close
Customer misuse
Internal foreign matter
Power element failure
Valve too small
Distributor tube/tubes restricted
Restricted with foreign matter
Kinked
I�D� reduced from previous compressor failure
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