Roaring inside cab with A/C on - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jake Wade · 08-31-2013, 11:06 AM

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.

GM-power · 08-31-2013, 10:36 PM

Does it make the noise on the vent or heater settings?
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Jake Wade · 09-01-2013, 06:32 AM

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.

bigd65 · 09-01-2013, 09:06 AM

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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Jake Wade · 09-01-2013, 09:39 AM

Quote:

Originally Posted by bigd65

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

bigd65 · 09-02-2013, 10:19 AM

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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08-31-2013, 11:06 AM	#1
Jake Wade Registered User Join Date: Aug 2005 Location: Louisiana Posts: 711	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.

08-31-2013, 10:36 PM	#2
GM-power Registered User Join Date: Mar 2012 Location: Little Rock, Arkansas Posts: 770	Re: Roaring inside cab with A/C on Does it make the noise on the vent or heater settings? Posted via Mobile Device __________________ 1979 Sierra Classic Heavy-half 1996 Silverado x-cab "the daily"

09-01-2013, 06:32 AM	#3
Jake Wade Registered User Join Date: Aug 2005 Location: Louisiana Posts: 711	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.

09-01-2013, 09:06 AM	#4
bigd65 Registered User Join Date: Mar 2000 Location: Clute, TX. Posts: 1,935	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.... Posted via Mobile Device __________________ 2004 Silverado Crewcab 1972 Chevy Monte Carlo 2017 Chevy Tahoe

09-02-2013, 10:19 AM	#6
bigd65 Registered User Join Date: Mar 2000 Location: Clute, TX. Posts: 1,935	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 Posted via Mobile Device __________________ 2004 Silverado Crewcab 1972 Chevy Monte Carlo 2017 Chevy Tahoe



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