General Trouble Shooting by
Technician
Blower Motor Does Not Operate
Possible Cause Inspection Solution
1. Blown Fuse Inspect fuse/wiring Replace fuse/wiring
2. Broken wire or bad
connection.
Check the fan motor for
ground and connections.
Repair wiring or connector
3. Fan motor malfunction Check the lead wires from the
motor with a circuit tester
Replace Motor
4. Fan motor switch
malfunction
Check power into and out of
the switch
Replace fan switch.
Blower Motor Operates Normally, Bur Air Flow is Insufficient
Possible Cause Inspection Solution
1. Evaporator inlet obstructed Check evaporator for
obstruction
Remove obstruction and clean
fins with air or water
2. Defective thermo switch,
(frozen Evaporator)
Check thermostat using a circuit
tester
Replace thermostat
Insufficient cooling, does not operate at all, or operates improperly
Possible Cause Inspection Solution
1. System low on refrigerant The high side pressure will be
low.
Repair any leaks evacuate
and charge.
2. Excessive Refrigerant The high side pressure will be
high
Recover refrigerant and weigh
in correct charge
The compressor does not operate at all, or operates improperly
Possible Cause Inspection Solution
1. Loose drive belt The belt is vibrating, slipping Adjust tension
2. Internal compressor
malfunction
The compressor is locked up
and the belt slips
Replace compressor
3. Low battery voltage Clutch slips Inspect charging battery
charging system
4. Faulty coil Clutch slips Replace clutch
5. Oil on the clutch Clutch slips Replace or clean clutch
surface
6. Open coil Clutch does not engage Replace clutch
7. Broken wiring or poor
ground
Clutch will not engage Inspect ground and connection
and repair
8. Wiring Harness components Test the conductance of the
HP Binary Switch, thermostat,
etc
Repair or replace parts
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