41
Diagnostics
DIAGNOSTICS
Service Analyzer Charts
COMPRESSOR OVERHEATING
SYMPTOM
POSSIBLE CAUSE
CHECK/REMEDY
High superheat
(greater than 15°F
[-9°C] at coil)
Low charge
Check system charge�
Faulty metering device
Restricted cap tube, TEV (TXV)
Power element superheat out of adjustment internally
Foreign matter stopping flow
High internal load
Hot air (attic) entering return
Heat source on; miswired or faulty control
Restriction in liquid line
Drier plugged�
Line kinked�
Low head pressure
Low charge
Operating in low ambient temperatures
Suction or liquid line subjected to high heat
source
Hot attic / insulate liquid line
Hot water line
Low line voltage
Loose wire connections
Check wiring�
Power company problem, transformer
Have problem corrected before diagnosis continues�
Undersized wire feeding unit
Correct and complete diagnosis�
High line voltage
Power company problem
Have problem corrected�
High head
pressure
Overcharge
Check system charge�
Dirty outdoor coil
Clean coil�
Faulty or wrong size outdoor fan motor
Replace fan motor�
Faulty fan blade or wrong rotation
Replace fan blade�
Replace with correct rotation motor�
Recirculation of air
Correct installation�
Additional heat source
Check for dryer vent near unit�
Check for recirculation from other equipment�
Noncondensibles
Recover refrigerant� Evacuate and recharge system�
Equipment not matched
Correct mismatch�
Short cycling of com-
pressor
Faulty pressure control
Replace pressure control�
Loose wiring
Check unit wiring�
Thermostat
Located in supply air stream
Differential setting too close
Customer misuse
TEV
Internal foreign matter
Power element failure
Valve too small
Distributor tube/tubes restricted
Distributor tube
Restricted with foreign matter
Kinked
I�D� reduced from previous compressor failure
