12037 N Highway 99
Seminole, OK 74868
Phone (405) 382-0731
www.enviro-ok.com
www.safran‐
passenger
‐solutions.com
Copyright © 2020
Original Release
ATA 21‐00‐60
Page | 18
Table 4 Trouble-shooting
INDICATION
PROBABLE CAUSE
POSSIBLE SOLUTION
A. No System Power
1. Ground power not connected
1. Plug in ground power cart
2. Aircraft power switch off
2. Energize power switch
B. Power On But System Will
Not Operate
1. Air conditioner breaker off
1. Turn on
2. Air conditioner breaker failed
2. Replace
3. Air conditioner mode switch
failed
3. Replace
4. Failed pressure switch
4. Replace
5. Vented system
5. Pressure check, evacuate and
charge
6. Low ambient temperature
6. Normal cut out function
C. System Operates But Does
Not Cool
1. Low refrigerant charge
1.Charge as required
2. Overcharged system cutout
2. Reclaim refrigerant as required
3. Failed Compressor
3. Replace Compressor Drive
4. Failed Drive Motor
4. Replace Compressor Drive
5. Failed expansion valve(s)
5. Replace
6. Evaporator blower switch failed
6. Replace
7. Evaporator blower motor failed
7. Replace Evaporator Motor
8. Evaporator module air inlet
clogged
8. Remove Debris
9. Expansion valve inlet clogged
9. Remove Debris
10. Excessive moisture in system
10. Replace receiver dryer
11. Excessive oil in system
11. Drain excessive oil
D. Evaporator Noisy
1. Blower wheel out of round
1. Replace
2. Blower wheel hitting scroll
2. Align
3. Defective blower motor bearing
3. Replace Evaporator Motor
4. Loose mounting bracket
4. Tighten hardware
5. Air inlet clogged
5. Remove debris
E. Compressor Noisy
1. Defective compressor
1. Replace Compressor Drive
2. Loose mounting hardware
2. Tighten as required
3. Loose hose assembly
3. Secure as required
4. Loose fan blade
4. Replace Compressor Drive
