I just bought a 1991 Buick Roadmaster wagon. As soon as I figure out how to do pictures I will share. It is in very good shape with 34,857 miles. There are some minor problems one of which is the AC does not work. The compressor does not engage. Right now all I know is what I have read. I do not have much practical car repair experience. I am thinking the clutch does not engage because the pressure is to low. Even with the car off I would think the pressure switch would check closed with an ohm meter if I had any Freon in the system. I know where to go to get it pumped down and checked to see if there are any leaks. Now the hard part. From what I have read R12 is better for cooling than R134. R12 around here is $67 for 12oz. My car would take 3.12 lbs. or about $290.00 give or take. If I repair the leaks and go with the R12 how long will a charge last? Is it worth it or should I change over to R134?
I don't know the specifics of your system. On my Saturn I believe the low pressure limit switch is 40psi. Below that the compressor will not engage. You can try to jump the limit switch to provide power to the compressor clutch to ensure that it is indeed working. I wouldn't leave it on for more than a second or so. I know others will disagree, but I would just retrofit it to the R-134a refrigerant. The R-12 isn't getting any easier to find and if/when the system does leak again in the future there goes your R-12. While the R-134a is not as effective as the R-12 I still find it plenty acceptable. If you search around you should be able to find what kind of compressor is on your car and if GM "recommended" it capable in a retrofit situation. If I can find the list of "approved" compressors tonight I will post them. More than likely the compressor you have will work just fine. To do the retrofit right you will probably want to take it all apart and at the very least replace the o-rings with PAG oil compatible o-rings (not a bad idea to do anyway). It's up to you on the hoses, but they are usually cheap enough that it is worth it to do. You will also want to replace the drier. Not sure if your system has an orifice tube or not, but that would get replaced as well. The system will also need to be properly flushed to get all of the old R-12 mineral oil out. After that it is a matter of reassembling the system, adding the appropriate amount of oil to key components and charging it with refrigerant. If you are going to try some/all of this yourself I strongly recommend getting the factory service manual for your car. It will have a lot of very good information in there about your A/C system.
Check Craigslist for R-12. You can get 30 pound sealed tanks of it for about the 250-400 bucks in my area, and most of the listings say "will negotiate " too. There are always small cans on there for sale, just make sure they aren't all rusty on top where the fitting goes on and are the good stuff. The less cars on the road that use it the cheaper the prices for it are getting to be, that supply and demand thing. My daughter's next door neighbor is a mechanic and he fully charged up my old Vista Cruiser's AC in his garage with R-12 for a case of beer, that was a deal.
Sounds like a really nice wagon. If it were me I'd take it and have the AC comverted to R134. I have no idea whether the old Freon is better or worse. My late model truck freezes us out with R134. My 55 Chevy wagon has a modern AC/heat system which will use R134 if we ever get the hoses hooked up. In a month you'll be needing the heater anyway.
At Napa a 12 ounce can of R12 is going for $66.59...just saying the same size in 134a is $8.99. Food for thought.
If you decide to stick with R12, look on ebay. I got 2 12oz cans and 1 14oz can with hose for 60 bucks. I would suspect that as the cooler weather arrives, the "winter prices" on eBay may go down some due to less demand. I also bought a nifty little gauge for less than 10 bucks. It looks a lot like the chrome stick (pen-sized) tire pressure gauges. You can put it on the low pressure port and get a reading to see where you are. It has all the psi info printed right on it.
Thank you every one for the input. Just got off EBay, I think R134 is the way to go. Now I can search on how to change over. Again thank you.
OK, is there anyone actually in the industry that knows what's going on? I sold my automotive business in 2000 and went into the gunmaking business as a semi-retirement activity. By that time, R134a had become the new refrigerant standard and the manufacture of "new" R12 had been banned. You also needed to pass a certification test to buy existing stores of R12 in quantities over 1 lb cans. Prices skyrocketed with 30 lb cylinders going for as much as $600. A lot of blackmarketing was going on and in many cases the product was contaminated, or not even R12. I had a recycling machine to recover and clean R12 for re-use in my shop. Junkyards had to recover it from any cars they accepted or crushed.....and cars could no longer be stored with any fluids or lubricants in them. It had to be recovered and recycled as well. Waste oil products went from them paying me 60 cents a gallon to me having to pay to have it removed by a licensed recycler. It's now 13 years later. So, the question is "Where the hell is all this R12 coming from that is still available for purchase?" I would have thought that "existing stores" of the product would have been depleted years ago.
In my case OldFox the Denver Napa warehouse just happened to have several pallets of R12 left over from the closing of a warehouse DC in Mexico, and you're absolutely right I have to have a HVAC license number to even sell R12 over the counter. It's definitely being fazed out completely.
It's really not Steve, without a license it's not available to the public. I sell most of it to the local airport really. I guess those older planes are very expensive to convert.
The old planes I used to fly in we just opened the windows ........... They all had a big fan to cool us off.
