38
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
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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
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
