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 ow
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
Dierential 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
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