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'93 Cadillac AC Procedure

BillT on Thu June 09, 2011 3:43 PM User is offline

Year: 1993
Make: Cadillac
Model: DeVille
Engine Size: 4.9
Refrigerant Type: R-12
Country of Origin: United States

Trying to get the AC working again on my '93 Cadillac DeVille.

So far I have put in a new Compressor and I've got a new Orifice Tube and Dryer ready to install.

We have decided to switch from R-12 to 134.

Then I believe the next step is to work the Codes from inside the car, but not sure on how to procede on it.

Any help would be appreciated.


Edited: Thu June 09, 2011 at 3:45 PM by BillT

NickD on Thu June 09, 2011 7:51 PM User is offline

Should install that 0.067" Ford White orifice or else you will be getting that service AC soon light every two seconds with R-134a. I stuck with R-12 on my 92.

Not sure what you mean by playing with the codes, once the system is properly charged and working properly, those lights go out. First you get a service AC soon, then when the charge really gets low, climate control will switch from AC to Econ.

chris142 on Fri June 10, 2011 12:36 AM User is offline

I've tried every tube and varied the charge amount and those computer comtrolled Cadillacs won't work on R134a.

NickD on Fri June 10, 2011 8:28 AM User is offline

Chick claimed success with the smaller orifice, another stunt was fooling with resistors on the low side thermistor. But will still never get the performance you can by sticking with R-12.

Least you have to do is to pull the compressor and flush it out with PAG oil, get an R-134a compatible accumulator, and flush out the rest of the system. But still have a problem with getting enough R-134a in it without the high side blowing its cork. Unless you want to install a parallel flow condenser.

Said the hell with that and just stuck with R-12, and the way things are going now, can practically find R-12 at the same price or a little more than R-134a.

BillT on Fri June 10, 2011 11:20 AM User is offline

Appreciate all the replies.

The reason I want to switch to 134 is because all my suppliers and garages are now saying that R-12 is not available anymore.

They said if I still have R-12 in my system, I could then use Freeze-12, but I have a brand new compressor on there now and it was recommended by a top notch AC shop to now go to 134. ??

Any replies or additional info would be appreciated.


Edited: Fri June 10, 2011 at 11:22 AM by BillT

NickD on Fri June 10, 2011 11:58 AM User is offline

Freeze 12 is a terrible suggestion 20% R-142B that is suppose to carry your mineral oil in your R-12 system, the rest is R-134a that will destroy the dryer in your accumulator. If that R-142B leaks out first, and it will, its lighter, have no oil carrier at all and your new compressor will seize, but some idiot will say the shear force of the R-134A will carry the oil for proper lubrication. Fine with me, do it in your own car and keep your big fat mouth shut. Require a lubricant that is miscible with your refrigerant, that hasn't changed since day one.

Sounds like your suppliers and garages are as just as dumb as mine are. Thank God for the internet. If you live in Canada, what they say is true, but this is the USA.

R-134a is a great refrigerant, provided your system was designed for it, beside making your system 100% compatible to deal with R-134a, for performance, should consider a parallel flow condenser as well. Its pressure is only about 10% greater than R-12, but only at the colder temperatures, above around a 120*F, its pressure skyrockets, so you need extra means to get rid of that heat. So many have to add not only the condenser, but higher capacity fans.

Is it worth it? Gosh, a friend offered me five cans of R-12 for five bucks a can, just said no, still have what I need left. Have any friends? You do require a 609 certificate to buy R-12, was going through that test with my 2 1/2 old granddaughter, she could pass it.

BillT on Fri June 10, 2011 1:34 PM User is offline

It took a few phone calls, but I was able to find some R-12 locally. I have to have the shop with the proper license get it for me, but that won't be any problem. The price isn't cheap, but lower than a price quote from a couple of years ago. It's 39.99 a can.


mk378 on Fri June 10, 2011 1:52 PM User is offline

If your new compressor came with PAG oil in it you'll need to remove all of it and change to mineral oil before using R-12. This entails removing the compressor from the car and working mineral oil through it while turning it on the bench. PAG oil reacts chemically with R-12 and becomes sludge. It is only suitable for R-134a systems.

Run away from the guy who thought it was proper to mix some Freeze-12 with remaining R-12.

BillT on Fri June 10, 2011 3:15 PM User is offline

I checked with my parts store and was told that the Oil in it is just about an ounce and a half of Shipping Oil, possibly called "ICE 32".

He told me that it is compatible with both R-12 and 134a.

Does this sound correct to you all?


Edited: Fri June 10, 2011 at 3:16 PM by BillT

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