3-6
T-312
Table 3-5. General System Troubleshooting Procedures - Continued
INDICATION/
TROUBLE
POSSIBLE CAUSES
REFERENCE
SECTION
3.3.5 Control System Malfunction
Will not control
Sensor or transducer defective
Relay(s) defective
Microprocessor malfunction
4.13, 4.15 or
4.14
Check
Check
3.3.6 No Evapotator Air Flow Or Restricted Air Flow
Air flow through coil blocked
Coil frosted over
Dirty coil
Dirty filter
Defrost coil
Clean
Clean/Replace
No or partial evaporator air flow
Motor running in reverse
Motor(s) defective
Motor brushes defective(main evaporator)
Evaporator fan loose or defective
Fan damaged
Return air filter dirty
Icing of coil
Fan relay(s) defective
Safety device open
Check
Repair/Replace
4.18/4.19
Repair/Replace
Repair/Replace
Clean/Replace
Clean/Defrost
Check/Replace
1.6
3.3.7 Expansion Valve Malfunction
Low suction pressure with high
superheat
Low refrigerant charge
Wax, oil or dirt plugging valve orifice
Ice formation at valve seat
Power assembly failure
Loss of bulb charge
Broken capillary
4.5 and 4.7
4.6
4.6
4.11.1
4.11.1
4.11.1
Low superheat and liquid slugging
in the compressor
Superheat setting too low
Ice or other foreign material holding valve open
4.11
4.6
3.3.8 No Or Insufficient Heating
Insufficient heating
Dirty or plugged heater core
Coolant solenoid heat valve(s) malfunctioning or plugged
Low coolant level
Coolant bypass heat valve open or malfunctioning
Strainer(s) plugged
Hand valve(s) closed
Water pumps defective
Auxiliary Heater malfunctioning.
Clean
Check/Replace
Check
Check/Replace
Clean
Open
Repair/Replace
Repair/Replace
No Heating
Coolant solenoid heat valve(s) malfunctioning or plugged
Microprocessor malfunction
Pump(s) malfunctioning
Safety device open
Check/Replace
Replace
Repair/Replace
1.6
NOTE:
Refer to Model 05G Compressor Manual, Form No. 62-02756.