PSD-QS (02/16)
Page 49
2) System
Problem /
Symptom
Likely Cause(s)
Correction
A. System does not
run.
Note: Some digital
thermostats have
a built-in five-
minute time
delay
.
1. Thermostat fault.
1. Adjust thermostat settings. / Replace
thermostat.
2. Power supply problem (AHU /
compressor unit).
2. Check power supply for adequate
phase and voltage. Check wiring to
system and external breakers or fuses.
3. Control voltage problem.
3. Check for 24V on terminal strip
between “R” and “C”.
4. Shut off by external thermostat or
thermostat is defective.
4. Check operation of thermostat.
5. System off on high pressure / low
pressure switches or discharge
temperature switch.
5. Reset limit switch. Analyze system for
root cause.
6. Internal component or connection
failure.
6. Check for loose wiring. Check
components for failure.
7. Compressor contactor not pulling in.
7. Check for 24V across contactor. Trace
24V circuit and components between
“Y” and “C” to locate fault. Repair or
replace as necessary.
8. Faulty run capacitor or start
components.
8. Test each and replace as necessary.
9. Compressor windings shorted or
grounded.
9. See compressor diagram/ replace the
compressor.
B. System runs for
long period or
continuously.
1. Thermostat fault.
1. Adjust thermostat settings / Replace
thermostat.
2. Refrigerant undercharged.
2. Repair leak. Evacuate and recharge
system.
3. Component failure (cooling mode).
3. Check pressures and electrical circuits
for abnormalities.
4. Outdoor thermostat not connected or
failed (heating mode).
4. Check outdoor thermostat and electric
supplemental heat operation. Confirm
proper wiring.
5. Reduced air flow.
5. Check air ducts for leaks and repair.
Check blower operation. Check air
filter(s). Remove air flow restrictions
(min.400 CFM/ton).
6. Four-way valve is short circuiting
refrigerant and bypassing hot gas to
suction.
6. Replace four-way valve, evacuate,
recharge and start-up system.
7. Unit undersized.
7. Contact ETI Technical Support at 863-
701-0096.
C. System blows
fuses or trips
circuit breaker.
1. Inadequate circuit ampacity.
1. Note electrical requirement and correct
as necessary.
2. Short, loose or improper connection
in field wiring.
2. Check field wiring for problems.
3. Internal short circuit. Loose or
improper connection in system.
3. Check wiring in system. See
appropriate wiring schematics and
diagrams. Test components, especially
the compressor, for shorts and grounds.
Figure 36. System Troubleshooting Chart
Summary of Contents for Prime-025
Page 15: ...PSD QS 02 16 Page 15 Figure 8 PSD Compressor Unit Electrical Schematic 230 1 60...
Page 16: ...PSD QS 02 16 Page 16 Figure 9 PSD Compressor Unit Electrical Schematic 230 3 60...
Page 17: ...PSD QS 02 16 Page 17 Figure 10 PSD Air Heating Cooling Water Heating Application...
Page 18: ...PSD QS 02 16 Page 18 Figure 11 PSD Air Heating CoolingWater Heating Field Wiring Diagram...
Page 20: ...PSD QS 02 16 Page 20 Figure 11a SureStart Mode of Operation...
Page 27: ...PSD QS 02 16 Page 27 Figure 15 Disassembled Plug Connector...
Page 34: ...PSD QS 02 16 Page 34 Figure 24 PSD Internal Flow Schematic...
Page 35: ...PSD QS 02 16 Page 35 Figure 25 PSD Piping...
Page 37: ...PSD QS 02 16 Page 37 Figure 26 Evacuation of PSD System...
Page 39: ...PSD QS 02 16 Page 39 Figure 27 Initial Charge of PSD System...
Page 41: ...PSD QS 02 16 Page 41 Figure 28 Final Charge of PSD System...
Page 44: ...PSD QS 02 16 Page 44 Figure 32 Start Up Process...
Page 53: ...PSD QS 02 16 Page 53...
Page 54: ...PSD QS 02 16 Page 54...
Page 55: ...PSD QS 02 16 Page 55...
Page 56: ...PSD QS 02 16 Page 56...
Page 57: ...PSD QS 02 16 Page 57...
Page 58: ...PSD QS 02 16 Page 58...
