Hello, I am new to this news group as well as a relatively new owner of 89 900 convertible. My question if you would be so kind in answering is, has anyone swapped out the Air Conditioner on a 900 to use the freon R-134a instead of the R-12 that it was originally equipped with? How big of a pain is it? Did you use a kit? Or do you just pay the $100 a pound or so for the R-12? The A/C is currently not working but my intentions are to keep this car as long as possible so I would like to get it working just in case. Thanks for your time and consideration in this matter. Respectfully - Monte
Paying $100 a pound is not very cost effective. If you want to keep the car for awhile with working A/C, my opinion is to convert. Just keep in mind that the effectiveness (cooling power) of the A/C system is somewhat reduced when R-134a is used in a system designed for R-12.
Most kits consist of a few cans of R-134a (with lubricant), a valve to open the cans and fill the system, and adapters for the high and low pressure ports on the A/C system which indicate to anyone servicing the car in the future that it is equipped with R-134a. One of the issues with switching from R-12 to R-134a is that a different lubricant is needed. The lubricant for R-134a often causes compressors designed for use with R-12 to wear a bit sooner. This might not really be a problem if you need to replace your compressor to effect the repair since all compressors recently manufactured (or remanufactured) are designed to work with R-134a.. If you must replace the compressor (or any other major component of the A/C system) you should probably replace the Receiver/Drier too. New compressor warranties usually require this. You might also want to replace the expansion valve while you have the system open. They sometimes get gummed up, and you don't want to open the system again for this relatively inexpensive part.
Before you open the system, you may want to check that the fuse for the A/C system is still good. On my 9000 the radiator fan associated with the A/C system sometimes binds, overloads the circuit and opens the fuse. The same fuse operates the compressor, so the entire A/C system shuts down -- with the ACC fan still going at full speed. I just give the fan a turn by hand and it usually keeps working properly for the rest of the summer.
It's absolutely essential to replace the reciever/dryer when you do this conversion, and you really should replace the expansion valve as well. Believe me, the extra 50 bucks or so for these parts is well worth it in the long run. Also make sure you get the kit that comes with all new O-rings and ester oil. When you open up the system, flush it out with refrigeration solvent and blow all the residue out with compressed air. I can't stress enough how important it is for the system to be absolutely clean inside. You need to remove any trace of the old oil as it will react badly with R134a. Before you charge it you'll need to pump it down to as near a perfect vacuum as you can get. If you don't have access to a vacuum pump, an old refrigerator or air conditioner compressor will usually do the trick.
Done right, you shouldn't notice much reduction in capacity and you can buy refrigerant in the future for just a few bucks a pound. Not to mention it's much better for the environment.
The A/C on my 86 900 T went out a couple years ago. My wife's 85 900T experienced the same last year. I found that using hydrocarbon replacement worked well. It is cheap and you can put it in without having to change anthing else. It is supposed to work better than R-12; it seems to work at least as well.
The down side is that it is flammable. Should a hose burst or if you run into something, there is a possibility of fire, and apparently it has happened. The up side is there is a flame retardant in it and you have less of it in your system than in a standard one pound can of propane.
It seems to be a 50/50 mix of propane and butane, with a flame retardent. a six ounce can replaces a one pound can of R-12.
I have found it works well and we have had no problems. If you decide to take this route, put a can in and if it works, call it good. Next time the air blows warm, put in another can.
I have found the standard way of checking fill with guages and the sight glass do not work with this refrigerant.
You still have to change the fittings (Checker sells them for around $12) and be sure to get the kit with 4 fittings as there are two kinds of R-12 fittings and if you get the pair only kit it might not have the ones you need.
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