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Revision A
7.8
Cab Air Troubleshooting
Problem
Solution
Section
Symptom: The blower fan will not run.
Burned out motor
Contact Dealer.
—
Burned out switch
Contact Dealer.
—
Motor shaft tight or bearings worn
Contact Dealer.
—
Faulty wiring
—
loose or broken
Contact Dealer.
—
Blower rotors in contact with housing
Contact Dealer.
—
Burned out motor
—
—
Symptom: The blower fan is operating, but air doesn
’
t blow into the cab.
Dirty fresh air filter
Clean fresh air filter.
Inspecting and Cleaning Fresh Air
Intake Filter Element, page 278
Dirty recirculating air filter
Clean return air filter.
5.9.1 Servicing Return Air Filter, page
283
Evaporator clogged
Clean evaporator.
Cleaning Air Conditioning Evaporator
Core, page 333
Air flow passage blocked
Remove blockage.
—
Symptom: Heater is not heating.
Heater shut-off valve at engine closed
Open valve.
3.10.1 Heater Shut-Off Valve, page 61
Defective thermostat in engine water
outlet manifold
Replace thermostat.
Contact Dealer.
Heater temperature control defective
Replace control.
Contact Dealer.
No thermostat in engine water outlet
manifold
Install thermostat.
Contact Dealer.
Symptom: Air louvers emitting odor.
Plugged drainage hose
Blow out hose with compressed air.
—
Dirty filters
Clean filters.
Contact Dealer.
Symptom: Air conditioning is not cooling.
Low refrigerant level
Add refrigerant.
Contact Dealer.
Clutch coil burned out or disconnected
Contact Dealer.
—
Blower motor disconnected or
burned out
Contact Dealer.
—
Switch contacts in thermostat burned
excessively, or sensing element
defective
Replace thermostat.
Contact Dealer.
Compressor partially or
completely seized
Remove compressor for service or
replacement.
Contact Dealer.
Condenser fins plugged
Clean condenser.