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Not sure if R12 or R134a? Way to test for this?

bill190 on Sun June 14, 2009 10:31 PM User is offline

Year: 1992
Make: GMC
Model: Sierra 2500
Engine Size: 5.7L
Refrigerant Type: ???
Country of Origin: United States

I bought a used GMC truck.

It has the A/C high pressure/low pressure connectors for R134a gauges, but the label on the accumulator still says R-12 and there are no other labels indicating it was converted to R134a.

So is there a way I can test the refrigerant to see if it is R12 or is R134a?

The A/C is working OK, so I don't want to disassemble it to look at O rings or whatever.

GM Tech on Sun June 14, 2009 10:43 PM User is offline

The new acr2000 recovery machines that is required equipment at all GM dealers (should be some available shortly) test the refrigerant for type and percent air-- so yes it is done on any recovery that the shop uses this machine-- also, any good shop will have a separate refrigerant identifier.....Itwould be my guess since it has the retro fittings, that it is 134a--

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

torque395 on Mon June 15, 2009 7:02 PM User is offline

R12 systems have different charge ports, can taps, etc. Everything is different. I would think it would be some what difficult to put R12 in it with retrofit fittings and definitely unlikely that it has R12.

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1996 Chevy Suburban 2500 4x2 6.5L Turbo

Cussboy on Mon June 15, 2009 8:26 PM User is offline

I can test gases at my lab with GCMS instrument, positive identification. I inject a sample with a syringe; the sample can be gas inside a vial with a rubber septum cap. I have identified refrigeration oils by FTIR spectrum.

mk378 on Tue June 16, 2009 12:13 PM User is offline

When trying to sell a used truck, instead of a proper conversion it's pretty common to slap adapters on and just gas in some R-134a on top of whatever R-12 may be left. It just needs to be cold for the test drive. This is not legal, and also you're counting on the R-12 to push the oil around. Since the leak is still there, people may think it's a converted system and do repeated toppings of 134a. But eventually all the R-12 will be gone, the oil will not return to the compressor, and compressor will fail.

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