Page 17
Installer’s Guide
8. Defrost initiates on approximately 30/45
minute intervals.
1.TEST_COMMON pin shorted to TST pin?
Y
Remove short.
2. Do both sensors check OK?
N
Replace defective sensor (Clear coil and reset
Emergency heat light).
Y
Complete SYMPTOM #3.
3. Verify correct system charge.
Adjust as needed.
4. Verify a "forced defrost" terminates less than 15
minutes.
N
Replace defrost control.
5. OD fan motor off in defrost.
See SYMPTOM #9.
6. Verify proper SOV operation.
Replace if necessary.
9. OD fan runs during defrost.
Replace defrost control.
10. No SOV delay on defrost termination.
Has J1 been cut?
Y
The soft-switch time is defeated when J1 is
cut.
N
Replace defrost control.
11. ODS-A burned out.
1. B to T greater than 10 volts?
Y
Check low voltage wiring for miswire.
N
Check for short in low voltage wiring.
12. On SCROLL bearing units, compressor
does not operate.
1. 24V R-B at board & 24V Y-B at board?
N
Repair low voltage wiring.
2. Check protective devices in YO circuit . 24V YO-B
present after 30 seconds.
N
Y-B signal or control may be intermittent
13. On SCROLL bearing units, no 30
second off delay at defrost initiation.
Check voltage between control terminals 2 and 7,force
a defrost cycle. Is 24V present for 30 seconds and 0V
thereafter?
N
Replace defrost control.
