Troubleshooting; Solid State Heat Pump Control; Table 5 Troubleshooting - Bard Q-TEC Q24H3DA Installation Instructions Manual

TROUBLESHOOTING

SOLID STATE HEAT PUMP CONTROL

TROUBLESHOOTING PROCEDURE
NOTE: A thorough understanding of the defrost
cycle sequence is essential. Review that
section found earlier in this manual prior to
troubleshooting the control.
1. Turn on AC power supply to unit.
2. Turn thermostat blower switch to "fan on";
the indoor blower should start. (If it doesn't,
troubleshoot indoor unit and correct problem.)
Sympton Description, Check & Possible Causes
1. Check for LED illumination.
Is there an LED illuminated on the board (flashing)?
2. Check for error codes.
Is the LED flashing a Code?
3. Check for power at board.
Is there 24 volts AC between R and C?
4. Check codes.
What code is blinking?
5. Compressor delay active.
Wait for 5 minute delay or jump board's "speed up pins".
Compressor
will not start 6. Low pressure fault.
(heating or
7. High pressure fault.
cooling)
8. Check for Compressor input signal.
Is there 24 volts AC between Y and C?
9. No power to board.
10. Check for Compressor output signal.
Is there 24 volts AC between CC & C?
11. No "Y" compressor input signal.
12. No "CC" compressor output signal.
13. Faulty board.
Fan outdoor
Heat pump control defective
motor does
not run
Motor defective
(cooling or
heating except
Motor capacitor defective
during defrost)
Reversing
Heat pump control defective
valve does not
energize
(heating only)
Reversing valve solenoid coil defective
Unit will not
go into defrost Temperature sensor or heat pump control defective
(heating only)
Unit will not
come out of
Temperature sensor or heat pump control defective
defrost
(heating only)
Blink
Slow Normal function (1.0 sec on/1.0 sec off)
Fast Compressor Delay timer active (0.1 sec on/0.1 sec off)
1 Low pressure switch failure
Manual 2100-653
Page 38 of 44
TABLE 5
Troubleshooting
Yes = go to Step #2; No = go to Step #3
Yes = go to Step #4; No = go to Step #8
Yes = go to Step #13; No = go to Step #9
Code "1", go to Step #6; Code "2", go to Step#7; Fast Blink, go to Step #5
Check for proper operation; if still needed, go back to Step #1.
Check wiring circuit and unit pressures.
Check wiring circuit and unit pressures.
Yes = go to Step #10; No = go to Step #11
The unit either does not have unit voltage, the transformer is bad or the unit wiring is incorrect.
Yes = go to Step #12; No = go to Step #13
Check thermostat wiring, incorrect phase of unit (see section on Phase Monitor), and finally unit wiring.
Check compressor contactor for proper operation and finally check compressor.
Replace defrost board.
Check across fan relay on heat pump control. (Com-NC)
Replace heat pump control.
Check for open or shorted motor winding. Replace motor.
Check capacitor rating. Check for open or shorted capacitor. Replace capacitor.
Check for 24V between RV-C and B-C.
1. Check control circuit wiring.
2. Replace heat pump control.
Check for open or shorted coil.
Replace solenoid coil.
Disconnect temperature sensor from board and jumper across "SPEEDUP" terminals and "SEN
JMP" terminals. This should cause the unit to go through a defrost cycle within one minute.
1. If unit goes through defrost cycle, replace temperature sensor.
2. If unit does not go through defrost cycle, replace heat pump control.
Jumper across "SPEEDUP" terminal.
This should cause the unit to come out of defrost within one minute.
1. If unit comes out of defrost cycle, replace temperature sensor.
2. If unit does not come out of defrost cycle, replace heat pump control.
LED Blink Codes
Function
3. Turn thermostat blower to "auto" position. Indoor
blower should stop. NOTE: Many models have a
1-minute blower time delay on "off" command;
wait for this to time-out.
4. Set system switch to "heat" or "cool". Adjust
thermostat to call for heat or cool. The indoor
blower, compressor and outdoor fan should start.
NOTE: If there was no power to 24 volt transformer,
the compressor and outdoor fan motor will not
start for 5 minutes. This is because of the
compressor short cycle protection.
What & How to Check/Repair
Blink Function
2 High pressure switch failure/"Soft" Lockout
3 Defrost mode active
4 High pressure switch failure/"Hard" Lockout