Hi,

New guy here. The a/c in my burb has a slow leak in the rear coolant line at the evaporator. Last year took it in to find the leak and they found it and recharged the system all for about $350. The charge lasted all year til the end of a/c season. I didn't have the money or the time to fix the leak this year so this year when the system was again blowing hot air, I decided to recharge on my own and save some $. Thing is, I bought a recharge kit with a simple pressure guage and attached it to the appropriate low pressure port. The reading initially was about 25 psi. and the compressor was not coming on. I then added refrigerant to about 40 psi and the compressor began to cycle on and off. so the instructions say not to add to above 55 psi. But I am getting 2 readings, a high reading when the compressor is off and a low one when it comes on. So I added enough refrigerant to get the compressor off reading to 55 psi and when it comes on the reading drops to 25 psi. I'm still not getting cool air in the cab. I am heasitant to add more refrigerant as the high reading is at the max recommended. Anyone have an idea what's going on. There was no info in the instructions about 2 different readings as the compressor cycles. Thanks

 

I've never used the equipment you have to fill a/c systems...but usually a properly filled system has a static pressure of at least 55psi depending on the ambient temperature. A static reading is taken with the system off for 15 minutes and the high and low sides have equalized.

 

Bonzoso: Welcome to the forum.

If memory serves me correctly, the low side pressure w/ the compressor running on an R134a system at 90*-95* should be about 55psi. There's no criteria for when the compressor is not running as it is dependent upon temperature and you don't learn anything from it. So if you are only reading 25 on the low side running, then you don't have enuf freon in it yet.

I thought you said they fixed the leak last year. If so, why did it all leak out again?

 

thanks for the replies. Nope, they found the leak and recharged. They wanted over a grand to do the repair (new lines, new condenser). They said it may hold for the summer so I took the chance and it did. I was going to tackle it this year, myself, but never got to it. I suspected that the reading I should use was the one with the compressor running but wanted to check with you all before I added more refrigerant. Thanks again.

 

I don't know how effective they are but some cans of freon have a leak stopper in them. You might try that to see if that would help you out.

 

static pressure when referenced to temperature is an indicator of charge level. filling a systems with a tx valve (do you have rear a/c?) this way probably isn't a good idea...what ever criteria you use, filling an a/c system this way...its not accurate.

 

I wouldnt recommend on using a leak stopper unless you plan to do all your own a/c work from now on. A lot of places will refuse to touch a system with the leak stoppers in them or charge extra due to the chance of clogging machines/gauges.