Air Conditioning, Fault Diagnosis

1. Compressor turn but no cool air

Reasons :

A. Inssuficient freon
> Fill freon, find any leak and repair

B. Blocked freon way by dirt on dryer, shown by no bubble thru the control glass even the pressure is normal
> Replace the dryer with new

C. Blocked freon way by dirt on expansion
> Replace the expansion with new

D. Less freon pressure, no leak
> Worn piston, replace compressor with new one

E. Rough noise from compressor
> Worn compressor bearing, increasing heat. Overhaul compressor and replace bearing

F. Too fast for compressor clutch magnet to disengage
> Less power, worn magnet. Find problem, replace if necessary

G. Evaporator being frozen
> Lower temperature sensor, 3/4 max

2. Pitching noise when compressor turn on.

Reasons :

A. Slip belt
> Adjust and replace if necessary

B. Pully not center
> Replace pully

C. Worn pully shim, make pully and magnet engage. Also may happen when compressor not turning
> Replace with new

3. Compressor not turn on.

Reasons :

A. Switch not turn on
> Turn on switch

B. Less power, worn clutch magnet
> Check and repair, replace if necessary

C. Blown fuse
> Replace fuse with new

D. Slip belt
> Adjust and replace if necessary

E. Loosen power
> Check and repair

F. Broken thermosensor
> Replace thermosensor with new

4. Compressor not stop from turning on

Reasons :

A. It’s normal for some car manufacture
> Ask your car dealer for further information

B. Broken thermosensor
> Replace thermosensor with new

5. Bad smell appear when a/c turning on.

Reasons :

A. Fungus has founded on a/c system
> Do completly cleaning on a/c system

B. There is a leak of freon
> Find leak and repair. Find leak using UV light.

6. Engine RPM drop when a/c turn on

Reasons :

A. Broken a/c idle up
> Replace idle up with new

B. Vacuum leak
> Find leak and replace vacuum hose if necessary

C. Not right adjust of idle up
> Adjust idle up, to 900 – 1000 rpm

7. Black dust around compressor pully.

Reason :

A. Worn compressor bearing
> Replace bearing before get jammed

8. Oil drop on garage, clear color.

Reason :

A. Broken compressor seal
> Overhaul compressor and replace all seal for repair and preventive

9. Oil drop on garage, black color and stink

Reason :

A. Worn compressor bearing
> Overhaul compressor and replace bearing

10. A/c blower fan not working, not blown as direction mode

Reasons :

A. Less power
> Check power and earthed

B. Broken fan control
> Replace fan control

C. Broken fuse
> Check and replace fuse

D. Broken relay
> Check and replace relay

E. Disconnecting blower direction mode
> Check system and repair

F. Air blowing to any direction
> Worn blower direction seal foam. Overhaul blower system and replace seal

11. Heater not functioning

Reasons :

A. Blocked coolant line behind the blower
> Drain coolant and refill coolant

B. Leak has appears
> Find and repair

• Note :

1. When do the pipe connection after repairing, as task to preventive from leak by broken thread and not precision pipe connection, use a sealing tape on the pipe thread and use sealer on the bolt or connection.

2. Coolant system is has relation with cooling system, specially in heat exchanger process which a/c condensor and radiator placed side by side.

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