1992 saab 900s conv 2.1 ac problem

It is lubricated by the oil suspended in the refrigerant. When was it last re-gassed?

David.

David It was last regased 3 weeks ago. Thanks papa

Is it a belt squeal?

dave

>

Papa,

It my just be the clutch making the noise? If so, that can be replaced by itself. Have an AC repair shop give a quick listen and assessment

-Fred W

Was it a proper vauum down/dry, re-oil, weigh regrigerant and re-gas, or just a simple pump it back until it is cold refill?

I think it might have been a pump until it is refilled. But once in awhile while driving down the road I will hear the squeel (sounds like a belt squeel) without the air on but it is constant with the air on. thanks papa

Thing is, there's no such thing as a "top-up" as the only way of topping up would require knowledge of the quantity of what's in there in the first place!

David.

If you use the bubbles in the sight-glass as your measurement, then I'd say that there is a way to go from a measurably insufficient level, to a measureably acceptable level.

Quantity of refrigerant is generally ascertained by measuring the low side pressure when the compressor is operating.

-Fred W

If you connect a guage set to the low and high sides and then measure the temperature of ambient air outside and return air in the car and the suction line out of the evaporator you can determine the superheat which is a fairly good indication of refrigerant quantity. In practice many people just measure the low side pressure and the air temperature and guestimate though.

No, quantity is best measured from a known starting point, i.e. 0 and then adding it by weight. Saab (and everyone else) list the charge by weight, not by the low pressure gauge reading.

David.

fairly good or correct?, there's a difference. One is correct, the other can be either too little gas and consequently too little lubricant, the other is too much gas and high pressures leading to a stressed compressor and potential premature failure.

I know you can get the kits in Walmart etc and i'm sure many people are perfectly happy with them. All i'm saying is that there's the guesstimate/estimate whatever you want to call it and then there's the proper way as specified by the manufacturers which is why the people that do it properly, use scales and not just a pair of gauges.

Incidentally, not all cars have a high pressure gauge take off, Volvo

850 for example thus making the top-up concept even harder.

FWIW, I recently had my 9000 re-gassed, not that I suspected anything wrong with it, just that I didn't know the history of the A/C and wanted to have a known datum. My usual chap came round and connected the gauges and was pretty horrified by the high pressure shooting round to

400psi and what he thought was an audibly straining compressor.

As an experiment, he emptied the system and measured the recovered amount which was 1.2kg when the proper charge should be 950g.

Hopefully, i've spared my compressor a premature death. If people want to go ahead and guesstimate, that's just fine by me, it's not my money that's going to go on a new compressor. :)

David.

Yes it is the clutch making the noise. Upon visual inspection you can clearly see the clutch trying to move and making a squeel noise even with the air off. 2 yrs ago I had a rebuilt compressor installed ,can this be my problem should I have bough a new one. 3 Weeks ago I had a ac place charge the system ,but I dont know how it was done, I think it was just a fill and replace cant be sure. I would think they did it right, but these days you never know. Thanks for the input best regard papa

It's one of three common established and acceptable methods for charging residential central A/C systems and heat pumps and I've used it successfully in automotive systems as well, which I've found to be less critical overall, especially if they have a TXV rather than a more tempermental fixed orifice. Optimal charge varies slightly depending on outside ambient and inside return air temperature, the factory specified charge is a compromise that should be fine for most climates, a little over or under is not generally a problem.

The lubricant is separate from the refrigerant, you can get oil/refrigerant top off kits because when refrigerant leaks oil tends to leak as well but when charging a system from scratch the oil is added separately. The problem with way too much refrigerant is high head pressure and excessive load on the compressor, and too little results in not enough refrigerant to adaquately cool the compressor but there is some leeway.

I know the feeling. My Celica which I am getting rid of needed refilling. I know because I accidently opened one of the compressor lines instead of removing one of it's mount bolts when trying to get to something behind it, no gas wooshed out, but some dye dribbled.

no gass came out. As the Celica was a nasty R12 system, I had to find a replacement. Found an Ebay UK auction for 1 Kilo R49 or R314 (R12 drop in) and a valve/filler tube. As I had already "broken the seal" and was selling the car soon, and so few have working aircon anyway, I thought I might just give it a top up. System takes 700g R12 roughly, and R314 needs between 10 and 20% less. So with a set of kitchen scales, and the site glass, I got about 580-

600g of R314 regrigerant in. It is leaking. But only from the O ring I disturbed when I opened the pipe. Has stayed cold now for over a month. Was absolutley great at the end of June when it was toasting hot.

Once it has leaked out, I reckon getting the O-ring replaced, give it a proper drier/reciever replacement if I keep it, and a proper Vac/Dry, lube and regas will sort that out.

All old R12 users, look for R49/R413 (essentially the same thing), or RS24. RS24 was developed as a replacment for refrigerated trucks that used R12. All those three are added as a liquid rather than a gas. They work.