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Has my truck been convered to R134a?

john_u on Sun July 11, 2010 11:48 PM User is offline

Year: 1988
Make: GMC
Model: Sierra
Engine Size: 5.7

I'm driving my father's truck (1988 GMC Sierra). He doesn't know if it's been converted to R134a. That seems like a good bet, since we're in CA, and he knows the A/C has been "serviced" -- so mechanics have probably raised the issue.

But the possibility remains the truck's still using R12, and I wouldn't want to guess wrong: there's no sticker indicating a re-fit, the valve port fittings look original, and they don't fit an R134a recharging/guage kit I bought.

1. Is it out of the question a mechanic converted the system to R134a but didn't change valve port fittings?

2. Is there a simple way to check if the system contains R12 or R134a? (By smell?)

3. At engine idle the compressor cycles on/off literally ever 1 second; does that make lack of refrigerant the likely problem?

Using new valve adapters, I was able to get a tentative pressure reading of 55/25 psi, depending on compressor activation. I'm not sure what to make of that.

As you can probably tell, this is my first time working on A/C.

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John U.

Paso Robles, CA

Edited: Sun July 11, 2010 at 11:56 PM by john_u

TRB on Sun July 11, 2010 11:55 PM User is offlineView users profile

Refrigerant analyzed by a shop with the proper equipment will be able to tell what refrigerant is in the system or the purity of the refrigerant.

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john_u on Mon July 12, 2010 12:06 AM User is offline

Thanks -- this information might save a trip to the wrong garage. I guess I should call around and ask who has this kind of equipment.

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John U.

Paso Robles, CA

Cussboy on Mon July 12, 2010 9:18 AM User is offline

If it's been converted it should have Acme type fitting connectors.

R-12 used 1/4 flare, and 3/16 flare on the high side in 1988 GM.

Can you post or link photos of the connectors?

Edited: Mon July 12, 2010 at 9:18 AM by Cussboy

TRB on Mon July 12, 2010 10:26 AM User is offlineView users profile

Quote
Originally posted by: Cussboy
If it's been converted it should have Acme type fitting connectors.



R-12 used 1/4 flare, and 3/16 flare on the high side in 1988 GM.



Can you post or link photos of the connectors?

True if they followed procedures! What if they used lets say an HC or another Internet blend. Only way to tell what's in a system it to have the refrigerant analyzed.



-------------------------
When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

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