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R12 or 134A?; How do I determine if my 1991 AC has been converted to 134A?
Topic Started: Aug 5 2017, 09:04 PM (459 Views)
richligh
Fresh Fish
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Bought a 1991 Geo Metro and AC is blowing warm air. Don't know what to charge it with. richligh

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David95237


Have to look at your fittings. If they are quick disconnects it is 134. If they are 1/4" flares its r12.
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suzukitom
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Tom

R-12 fittings are usually smaller diameter and are screw on. R-134a fittings look like a snap on quick coupler.

Sometimes DIY'ers do not change the fittings during a conversion so it is not certain to draw a conclusion by looking ar the fitting type.

If professionally converted, it should have a sticker somewhere in the engine compartment showing details.

The only way to tell for sure is for an A/C shop to do a gas verification check.
Edited by suzukitom, Aug 5 2017, 11:31 PM.
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richligh
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Thank you David 95237. Now I need to figure out why the high-pressure side only goes up to 50 pounds.
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richligh
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Thank you suzukitom!
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MetroKid
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There's normally a small yellow or orange sticker on the passenger side of the engine bay that says r12 or 134A.
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turbogts22
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Dean

The bigger issue is determining if it has the correct oil in the system. Often times DIY mechanics just slap on the retrofit fittings and charge it up with R134a. It doesn't mix with the old mineral oil and therefore doesn't do a good job of returning the oil to the compressor. It'll work for awhile but eventually kills the compressor.
I always flush everything out repeatedly with acetone and DRY compressed air. Then refill the compressor with about 3.5 oz of double end capped PAG 46 oil. Recharge with the correct amount of R134a for the system and usually all is well.
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geogonfa
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Just my .02...here is what 134a fittings look like...

Posted Image

this what you need to change the fittings...

https://www.walmart.com/ip/ID-Quest-Ez-Chill-R-12-to-R-134a-Retrofit-Service-Port-Adapters/16888797

First thing to do after changing the fittings is just add some dye to the system so you can find your leak...repair it
Then since it's not an 134a designed system I recommend eviro-safe...

https://www.amazon.com/Enviro-Safe-R134a-Refrigerant-Dye-Cans/dp/B01DPSPTZO/ref=sr_1_2?ie=UTF8&qid=1502127111&sr=8-2&keywords=envirosafe+refrigerant

...don't have to change the oil, and cools better than r12 without being as heavy and corrosive as 134a...

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turbogts22
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Dean

I've used the hydrocarbon refrigerants in the past with varying degrees of success depending on the system. The biggest issue I run into is when some people find out it's flammable they have a hissy fit.
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suzukitom
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Tom

turbogts22
Aug 7 2017, 02:31 PM
I've used the hydrocarbon refrigerants in the past with varying degrees of success depending on the system. The biggest issue I run into is when some people find out it's flammable they have a hissy fit.
As long as the A/C is not having the hissy fit..

:lol
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richligh
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Thanks for all the good info. I'm now convinced that the compressor is bad. Any advice on where to obtain a used or rebuilt and approximately what it should cost would be appreciated. Thanks again. Rich
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MarkZ28


Propane, butane both will work well and blow cold with less pressure than R134 needs. Large commercial units can use anhydrous ammonia, but very dangerous.
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Moringa
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Living BOT

turbogts22
Aug 7 2017, 10:43 AM
The bigger issue is determining if it has the correct oil in the system. Often times DIY mechanics just slap on the retrofit fittings and charge it up with R134a. It doesn't mix with the old mineral oil and therefore doesn't do a good job of returning the oil to the compressor. It'll work for awhile but eventually kills the compressor.
I hadn't heard that one. I have heard that the R12 oil is organic, and the R134 oil is synthetic. I was under the impression that all you needed to change, in the changeover, was the fittings, and the receiver/dryer.
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Metromightymouse
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Powdercoat Wizard

Moringa
Aug 7 2017, 10:32 PM
turbogts22
Aug 7 2017, 10:43 AM
The bigger issue is determining if it has the correct oil in the system. Often times DIY mechanics just slap on the retrofit fittings and charge it up with R134a. It doesn't mix with the old mineral oil and therefore doesn't do a good job of returning the oil to the compressor. It'll work for awhile but eventually kills the compressor.
I hadn't heard that one. I have heard that the R12 oil is organic, and the R134 oil is synthetic. I was under the impression that all you needed to change, in the changeover, was the fittings, and the receiver/dryer.
:smackface
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