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8. Symptom: Low refrigerant discharge pressure
Possible Causes
Low suction pressure
Incorrect fan control settings
9. Symptom: High refrigerant discharge pressure
Possible Causes
System overcharged with refrigerant (especially at low ambient temperature in
heating mode)
Dirty tube and fin surface
Non-condensables in heating mode
Incorrect fan control settings
Condensing fans not operating in cooling mode
EXV does not function properly (especially at low ambient in heating mode)
Overshooting LWT temperature in heating mode
10. Symptom: Low chilled water temperature
Possible Causes
Temperature controllers set too low
Low water flow
Faulty system temperature sensor
11. Symptom: High chilled water temperature
Possible Causes
Load higher than capacity of heat pump
Loss of refrigeration charge
Fouled evaporator
High water flow rate
Faulty system temperature sensor
12. Symptom: Compressor thermal protector switch open
Possible Causes
Operating beyond design conditions
Discharge valve partially shut
Faulty compressor overload
13. Symptom: No low voltage (24 Vac)
Possible Causes
Transformer primary side fuse open
Transformer defective
No primary voltage on transformer
ARTC-SVX009A-EN
Heat Pump Troubleshooting
Potential Solutions
See 'Low refrigeration suction pressure'.
Check fan settings.
Potential Solutions
Remove excess refrigerant.
Clean with compressed air or water spray; use fin comb if fins are bent.
Purge non-condensables.
Check fan functionality and settings.
Check fan functionality and settings.
Check EXV functions; check SSH settings.
Water system volume needs to increase; check stage band control settings.
Potential Solutions
Reset temperature setpoint.
Clean strainer; check pump, VFD, and differential pressure settings; check to
confirm electric and manual water valves are fully open.
Replace temperature sensor.
Potential Solutions
Refer to heat pump design specifications.
Check refrigerant charge.
Reverse flush evaporator; check strainer for debris.
Check pump, VFD and differential pressure settings.
Replace temperature sensor.
Potential Solutions
Check fan switch or fan pressure settings as appropriate.
Open valve.
Replace overload if external type provided.
Potential Solutions
Check fuse prong contact points; Replace fuse.
Replace transformer.
Check breakers, fuses; check power supply specifications.
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