Operating instructions

TM 11574A-OI
3-58
(2) No control power.
Step Probable Cause Remedy
1 Circuit breaker or fuse defective. Check for blown fuses IAW WP 3-10b(18)(i).
Replace blown fuse IAW 3-10b(18)(j)
Check for damaged or defective circuit
breaker IAW 3-10b(18)(q).
If circuit breaker is found to be defective,
replace IAW 3-10b(18)(r).
If fault is not corrected proceed to step 2.
2 Control transformer defective. Replace control transformer IAW 3-
10b(18)(g).
If fault is not corrected proceed to step 3.
3 Evaporator fan internal motor protector open. Refer to section 3-10b(12).
If fault is not corrected proceed to step 4.
4 Heat relay defective. Check heat relay IAW 3-10b(18)(e)w.
Replace heat relay IAW 3-10b(18)(e)x.
5 Heater termination switch open. Refer to section 3-10b(11).
If fault is not corrected proceed to step d (3).
(3) Unit will not heat or has insufficient heat.
Step Probable Cause Remedy
1 Heater(s) defective. Refer to section 3-10b(11).
If fault is not corrected proceed to step 2.
2 Heater contactor or coil defective. Replace contactor or coil IAW 3-10b(11)(b).
If fault is not corrected proceed to step 3.
3 Evaporator fan motor(s) defective or rotating
backwards.
Refer to section 3-10b(12).
If fault is not corrected proceed to step 4.
4 Evaporator fan motor contactor defective. Replace evaporator fan motor contactor
IAW 3-10b(11)(b)
If fault is not corrected proceed to step 5.
5 Controller malfunction. Refer to section 3-10b(11)(i).
If fault is not corrected proceed to step 6.
6 Defective wiring. Replace.
If fault is not corrected proceed to step 7.