Date: Sun, 31 Jul 2005 03:56:30 GMT From: "James Sweet" <jamessweetnospamail.com> Subject: Re: 1992 saab 900s conv 2.1 ac problem
> 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. > 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.