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62-11175 COMFORTPRO SERVICE MANUAL
3-10
SYMPTOM
PROBABLE CAUSE
SOLUTION
REFERENCE
Air conditioner runs
•
Driver Control Panel temp sensor
•
Replace Driver Control Panel
OK, but short cycles
defective
(cont.)
•
High pressure cut out due to:
•
Check:
a) Insufficient air flow
a) Air flow through condenser (fan)
b) Overcharge
b) Reduce charge to 64–68 oz.
c) Air in system
c) Purge air (vacuum system)
d) Defective switch
d) Replace
•
Low temp(de-ice) cut out due to:
•
Check:
•
2-1
a) Insufficient air flow
a) Air flow through evaporator
(fan, filter, vents closed)
b) Faulty expansion valve
b) Replace valve
c) Faulty de-ice sensor
c) Verify sensor operation by using
Temperature vs. Resistance Chart
•
A-11
d) Undercharge
d) Fix leak and recharge (64–68 oz)
A/C operates long
•
Shortage of refrigerant
•
Fix leak and recharge (64–68 oz)
•
2-1
or continuously
•
Driver Control Panel temp sensor
•
Verify sensor operation by using
defective
Temperature vs. Resistance Chart
•
Sleeper has an excessive heat load
•
Cover windows, close sleeper curtains
•
Sleeper has poor insulation
•
Insulate sleeper
•
Evaporator coil iced
•
Faulty EVAP temp sensor, Verify sensor
operation by using Temperature vs.
Resistance Chart
•
2-1
•
Restriction in refrigerant system
•
Determine location and repair
•
Dirty condenser
•
Clean condenser
•
CCU air filter dirty
•
Clean or replace CCU filter
•
A-3
Start capacitor open,
•
Potential relay is not operating
•
Replace
shorted, or blown
properly
•
Prolonged operation on start cycle
•
Check:
due to:
a) Low voltage to unit
a) Determine reason and correct
(see "Low Voltage")
b) Starting load too high
b) Check: pressure equalization
before compressor starts,
(5 minute timer faulty)
•
Excessive short cycling
•
Determine reason for short cycling
and repair (see "Unit runs OK, but
short cycles")
Potential relay defective
•
Line voltage to low or to high
•
Determine reason and correct
or burned out
•
Excessive short cycling
•
Determine reason for short cycling
and repair (see "Unit runs OK, but
short cycles")
•
Relay being influenced by a loose
•
Remount rigidly
and vibrating mount
Suction line frosted
•
Evaporator fan not running
•
Determine reason and correct
•
3-11
or sweating
•
Overcharge of refrigerant
•
Reduce charge to 64–68 oz.
•
2-1
Unit noisy
•
Loose parts or mounting
•
Find and tighten
•
Tubing rattle
•
Move object that is touching the
tubing to be free of contact
•
Bent fan blade causing vibration
•
Replace blade
•
Fan motor bearings worn
•
Replace motor