Operating instructions

TM 11574A-OI
3-62
Step Probable Cause Remedy
5 No evaporator air flow or restricted air flow. Refer to section 3-10b(11).
If fault is not corrected proceed to step 6.
6 Excessive frost on evaporator coil. Refer to section 3-11d.
If fault is not corrected proceed to step 7.
7 Evaporator fan(s) rotating backwards. Refer to section 3-10b(11) and 3-10b(12).
If fault is not corrected proceed to step 8.
8 Discharge pressure regulator valve defective. Inspect discharge pressure regulator valve
IAW 3-10b(16)(a).
Replace discharge pressure regulator valve
IAW 3-10b(16)(b).
If fault is not corrected proceed to step 9.
9 Suction modulation valve malfunction. Refer to section 3-10b(14).
If fault is not corrected proceed to step g (3).
(3) Suction and discharge pressures tend to equalize when unit is operating.
Step Probable Cause Remedy
1 Heat exchanger defective. Inspect heat exchanger IAW 3-10b(11)(e).
Replace heat exchanger IAW 3-10b(11)(e)1.
If fault is not corrected proceed to step 2.
2 Compressor valves defective. Refer to section 3-10b(5).
If fault is not corrected proceed to step 3.
3 Compressor cycling/stopped. Check IAW 3-10b(5).
s. Abnormal noise or vibrations.
(1) Compressor.
Step Probable Cause Remedy
1 Loose mounting bolts. Check for loose mounting bolts. Tighten
mounting bolts as necessary.
If fault is not corrected proceed to step 2.
2 Worn bearings. Refer to section 3-10b(5).
If fault is not corrected proceed to step 3.
3 Worn or broken valves. Refer to section 3-10b(5).
If fault is not corrected proceed to step 4.