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how to know if you have a bad fan clutch vs compressor clutch?
2004 chevy trailblazer
i know its one of the clutches from the screeching sound just not sure which one it is?
the a/c works and so does the fan. after an oil change i noticed the fan moving extremely slow and put my hand on it and it stopped right away, but when i turn my a/c on max the noise gets less noticeable. i live in ohio so the car gets covered in salt. the bolts just doing the oil change were all covered in the residue. so im not sure if one clutch is bad or both.
the only code is po410 secondary air intake
7 Answers
- CARL G HLv 78 years agoFavorite Answer
Both are easy to diagnose. The fan clutch usually has play in the hub and/or when the belt is slipped off has too much resistance or none at all. a slight amount is expected. The A/C clutch can be seen when running often spinning even when not turned on slightly. also it usually makes a lot of noise when the a/c is turned on and it engages. a loud squeal from the belt trying to turn it as well. I always recommend replacing the belt if this is occurring as well as the clutch.
Source(s): 32 year mechanic - MasTec 1970Lv 78 years ago
Thanks for providing the vehicle information!
If the A/C will NOT cool @ idle, but, will cool while driving, then you have a bad EVFC (Electro Viscous Fan Clutch), there is a TSB (Technical Service Bulletin) that has to do with checking for chafed EVFC wiring harness.
This is a common issue with the 4.2L T.B.
Scan the PCM (Powertrain Control Module) for code # P0526 (Cooling Fan Speed Sensor Circuit Malfunction)
If this code is stored, you have a problem with the EVFC and/or it's wiring harness.
TSB# 05-06-02-012
http://i1127.photobucket.com/albums/l629/mastec197...
http://i1127.photobucket.com/albums/l629/mastec197...
NOTE: The T.B. is equipped with an Electro Viscous Fan Clutch, it's RPM is controlled by the PCM, If you don't work on this stuff everyday, then why don't you do some research before answering!
Source(s): 28 Year Master, L-1 Technician - Michael SLv 78 years ago
This is no "bad fan clutch VS compressor clutch".
They are two different mechanisms that do two different things on two different systems of the car.
Compressor clutch you can look at it when you have the AC on and the front plate should turn then stop, then turn and stop with the compressor kicking on and off.
The fan clutch is tested by spinning it by hand, if it turns more than one revolution it's bad.
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- 8 years ago
That depends on the situation. A lack of ac at all, I'd look into the clutch there and the many other parts of that system. If the cooling fan to the radiator is the issue, that too can be complex in dealing with a fuse, relay, the fan motor itself and the computer that is watching coolant temperatures.
- Old Man DirtLv 78 years ago
If the compressor clutch is bad- the AC does not work.
If the fan clutch is bad- the engine overheats.
I would have thought GM would have moved on past fan clutches by now, how archaic.
