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Heat Pump Troubleshooting
14. Symptom: Thermal Expansion valve superheat too high
Possible Causes
Water/glycol temperature too warm
Obstructed filter dryer
Low refrigerant charge
Improper and not enough heat transfer at air coil
Sensing bulb not properly located
Defective or improper settings of EXV/TXV
15. Symptom: Thermal expansion valve superheat too low
Possible Causes
Sensing bulb not properly located
Defective thermostatic element (TXV is cooling mode)
EXV/TXV valve superheat setting is too low or not functioning properly
16. Symptom: Contactor/relay inoperative
Possible Causes
Coil shorted or open
Mechanical parts broken or jammed
Contacts pitted or burned
No 24 Vac to coil
17. Symptom: Freeze protection safety activated
Possible Causes
Heat pump setpoint is too low
Low water flow
Low suction pressure
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Potential Solutions
Check setpoints; check charge.
Replace dryer core.
Recharge refrigerant as per nameplate.
Check tube and fin surface; check fan settings.
Check if secured to pipe or insulated; check sensor position on pipe.
Check EXV/TXV functions; check EXV/TXV settings.
Potential Solutions
Check if secured to pipe or insulated; check sensor position on pipe.
Replace power head.
Check EXV/TXV settings and functionality.
Potential Solutions
Replace coil.
Replace assembly.
Replace contactors.
Replace secondary fuse to transformer; check transformer.
Potential Solutions
Use a proper setpoint.
Clean strainer; check pump, VFD and differential pressure settings.
See "low suction pressure".
ARTC-SVX009A-EN
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