42
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
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 heat pump coil Clean coil�
Faulty or wrong size heat pump 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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