Control System Malfunction; No Evaporator Air Flow Or Restricted Air Flow; Expansion Valve Malfunction; No Or Insufficient Heating - Carrier 68G5-105 Series Operation & Service Manual

Table 3-5. General System Troubleshooting Procedures - Continued
INDICATION/
TROUBLE

3.3.5 Control System Malfunction

Will not control
3.3.6 No Evapotator Air Flow Or Restricted Air Flow
Air flow through coil blocked
No or partial evaporator air flow

3.3.7 Expansion Valve Malfunction

Low suction pressure with high
superheat
Low superheat and liquid slugging
in the compressor

3.3.8 No Or Insufficient Heating

Insufficient heating
No Heating
NOTE: Refer to Model 05G Compressor Manual, Form No. 62-02756.
T-312
POSSIBLE CAUSES
Sensor or transducer defective
Relay(s) defective
Microprocessor malfunction
Coil frosted over
Dirty coil
Dirty filter
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
Low refrigerant charge
Wax, oil or dirt plugging valve orifice
Ice formation at valve seat
Power assembly failure
Loss of bulb charge
Broken capillary
Superheat setting too low
Ice or other foreign material holding valve open
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.
Coolant solenoid heat valve(s) malfunctioning or plugged
Microprocessor malfunction
Pump(s) malfunctioning
Safety device open
3-6
REFERENCE
SECTION
4.13, 4.15 or
4.14
Check
Check
Defrost coil
Clean
Clean/Replace
Check
Repair/Replace
4.18/4.19
Repair/Replace
Repair/Replace
Clean/Replace
Clean/Defrost
Check/Replace
1.6
4.5 and 4.7
4.6
4.6
4.11.1
4.11.1
4.11.1
4.11
4.6
Clean
Check/Replace
Check
Check/Replace
Clean
Open
Repair/Replace
Repair/Replace
Check/Replace
Replace
Repair/Replace
1.6