Operating instructions

TM 11574A-OI
3-61
r. Abnormal pressures (cooling).
(1) High discharge pressure.
Step Probable Cause Remedy
1 Condenser coil dirty. Refer to section 3-10b(7).
If fault is not corrected proceed to step 2.
2 Condenser fan rotating backwards. Refer to section 3-10b(8).
If fault is not corrected proceed to step 3.
3 Condenser fan inoperative. Refer to section 3-10b(8).
If fault is not corrected proceed to step 4.
4 Refrigerant overcharge or noncondensibles. Refer to section 3-10b(2)(e) and 3-
10b(3)(b).
If fault is not corrected proceed to step 5.
5 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 6.
6 Discharge service valve partially closed. Open discharge service valve.
If fault is not corrected proceed to step 7.
7 Suction modulation valve malfunction. Refer to section 3-10b(14).
If fault is not corrected proceed to step g(2).
(2) Low suction pressure.
Step Probable Cause Remedy
1 Suction service valve partially closed. Open suction service valve.
If fault is not corrected proceed to step 2.
2 Filter-drier partially plugged. Refer to section 3-10b(9).
If fault is not corrected proceed to step 3.
3 Low refrigerant charge. Check refrigerant IAW 3-10b(2)(e).
Recharge refrigerant IAW 3-10b(4).
If fault is not corrected proceed to step 4.
4 Expansion valve defective. Refer to section 3-10b(10).
If fault is not corrected proceed to step 5.