Roaring inside cab with A/C on
 

85 GMC 1/2 ton 2WD with a 305. This truck has the R4 style compressor.

What could cause a roar inside the cab when the A/C is on that fluctuates with RPM. Unfortunately it is at its worse at cruise speed, 1800-2100 RPM.

Just installed a brand new Four seasons compressor, dryer, and orfice.

It has the proper oil and the charge is correct.

BTW, I have new motor mounts and all factory brackets installed correct.

Proper tension on new belts also.

Not noticeable standing outside looking under hood.

Re: Roaring inside cab with A/C on
 

Does it make the noise on the vent or heater settings?
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Re: Roaring inside cab with A/C on
 

I have not tried that. It only does it when the compressor clutch is engaged.

I am guessing I have a bad compressor. It cools well though.

Re: Roaring inside cab with A/C on
 

If you converted it to R134, it's because the CONDENSOR does not have large enough hole to allow for the thicker R134.... Same problem with mine and same problem I had with my 85....
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Re: Roaring inside cab with A/C on
 

AHA! This could be it! If I bought a new direct fit condenser for my truck, Would it be compatible with R134?

Re: Roaring inside cab with A/C on
 

I would think you should be able to. Just make sure it's 134 compatable. The other is not even available anymore or at least cost effective, I'm sure someone will make one... I have to do the very same when I get my truck back from paint
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