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A/C Recharge


stokes

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I have been searching the archives but cant find the answer to this.How do I tell if my system was converted to R134a or if I still have R-12?Right now my DIC tells me the refrigerant is low/AC compressor is off.I have access to gauges and vaccuum.After evacuating do I have to add oil to the system?Thanks for any help on this.

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Look at the service ports with the caps removed. If they look like large tire valves, the system is R-12. If they look like air compressor disconnects, then the system is R-134a.

If the system was converted by a reputable shop, they should have applied a label indicating the system was converted.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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When I referred to air compressor disconnects, I was referring to the male disconnects - like you'd find on an impact wrench or other air tool.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Kevin,

I checked the fittings as you described and the low port (on the accumulater) looks like what you described as the 134a fitting and the high press tap looks like a "large tire valve".The label on the accumulater says R-12 and appears to be from the factory.

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Yep that sounds right, I converted a 85 Jag and they only put em on the low side cause thats the side they fill. It was probably done in the back yard with an old set of gauges and vacuum pump. If you have a new drier then it was done right.

Julio

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It's interesting that they left the old accumulator in the car. It's usually recommended that it be changed because air entering the system while the hoses are being changed can damge the desicant used to remove moisture from the refrigerent. Moisture from the air can sometimes cause premature failure of the desicant causing it to break up and clog the system. This probably isn't a problem but something to keep in mind for the future. I would also have the hoses checked too just in case. They need to be changed when converting from R-12 to R-134 because R-134 is a smaller molecule and will leak out of R-12 hoses.

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The hoses don't need to be changed - by 1992, the hose materials were changed to R-134a compliant as R-134a was 2 years away. My '86 Park Avenue has barrier hose from the factory.

I would have changed the accumulator. There will not be enough moisture to enter the system just from having it opened to change a component. The reason for the accululator change is the old R-12 accumulator will be saturated with R-12 mineral oil and that will reduce the performance of the R-134a.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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If I evacuate the system with a pump can I put Freeze 12 in it as it is.I have access to the gauges and pump.I checked the low press tap on the accumulater against a 2000 Jeep that was just refilled with R-134 and the fitting on my Caddy is smaller in diameter than the Jeep's.It's the same snap-on type,just narrower.Anyone have any ideas as to what that is about?

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Are you sure you are comparing the low pressure ports on both vehicles? If so, someone may have retrofitted your car with a refrigerant blend. I would not recommend Freeze-12 as it is 80% R-134a and 20% R-142. Rather than use Freeze-12, why not convert the car to R-134a?

If it were my car, I would remove the accumulator and compressor and flush the system to remove all the old oil. Drain the oil from the compressor as well. The type of oil that could be in there is a mystery at this point. Buy some PAG-150 refrigerant oil and add some to the suction port of the compressor while turning the clutch by hand until clean PAG runs out the discharge port.

Empty as much oil from the compressor and then add the perscribed amount of oil to the compressor suction port and add the balance to a NEW accumulator. Reassemble the system with new o-rings, and then evacuate the system with the vacuum pump. Add the amount of R-134a that is specified for R-12 and you should be all set.

This is one example where it makes sense to convert a car to R-134a. The other example is if there is a compressor failure requiring replacement of the compressor and accumulator.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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