Fan Belt

[Dellb]

Hi All
I have now got the air con fired up on my 1980 C3, and it’s lovely and cool. One very strange problem though. The pulleys are running true, and the pulley alignment and belt tension is spot on. However when the AC is on, and the engine is idling, the air con belt really flaps around making one hell of a racket, and hitting the compressor stay. Raise the rpm, and it goes away, and turning the AC off stops it. Has anyone else had this?

 

[Chuffer]

Have you checked for fore and aft play in the compressor pump bearings ? You stated that pulleys are aligned and belt tension is correct , so to me it suggests a problem on when the air con clutch is engaged and driving the compressor . I have not experienced this myself but just looking at it from a simple engineering point of view . Possibly only oscillates at certain revs .

 

[Dellb]

The entire AirCon system inc compressor, is brand spanky new. Hence the head scratching.

 

[Oneball]

Have you got the right belt arrangement?

From Wilcox

 

[Daytona Vette]

Check the brackets are tight on the compressor and all pulleys are secure - if there is no play in any of the mounting points of compressor or pulleys and alignment and tension of belts is correct - I would then look at the A/C belt being faulty and stretching or not gripping the pulleys - go get another brand of belt from another supplier

 

[Dellb]

That is my belt arrangement except, no air pump, and therefore only two tracks on the water pump

 

[johng]

Sounds to me as if you might have a resonance in the system. Have you tried running with the belt a bit looser or tighter?

 

[Roscobbc]

Hi All
I have now got the air con fired up on my 1980 C3, and it’s lovely and cool. One very strange problem though. The pulleys are running true, and the pulley alignment and belt tension is spot on. However when the AC is on, and the engine is idling, the air con belt really flaps around making one hell of a racket, and hitting the compressor stay. Raise the rpm, and it goes away, and turning the AC off stops it. Has anyone else had this?

Sounds like a harmonics issue - have you tried something really simple like changing idle rev's up or down?
Its not unknown for harmonics to affect alternator mounting brackets (they can fracture) - how 'solid' is compressor bracketing?

 

[Chuffer]

Also is it a toothed belt or a plain V belt ? A toothed belt might grip better .

 

[Oneball]

Have you got the right belts both length and width? Think they’re 11mm in metric.