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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--

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.

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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