a/c overpressurized?

[EHBOY]

Hi Guys... I've run a few searches yeilding no results so here's the question. I've a 95'ATX which blows COLD air at first for about 10min. but becomes warm after that. I purchased a can of oil/stopleak/refrigerant from walmart that comes with an in-line type pressure guage. I hooked the guage up on the a/c line (car off) by the firewall and it reads in the red. (meaning overpressurization.) Has anyone any ideas before i spend some $$$ having the system serviced? Thank You

 

[SHO_Driver]

Is the compressor still turning when it gets warm? If not it could be clutch related.

 

[BlackOnBlackATX]

i recently had a similar problem. if the actual compressor is not running your gauge will be in the red. take a broom handle and tap the side of the a/c pulley on the clutch face while the a/c is on. if the compressor kicks on you need a new clutch and coil most likely. i put a new compressor in for myself on saturday morning, so now im enjoying the cold air

let us know how it goes!

 

[EHBOY]

thats a great idea... i'm at work right now (3rd shift) but i'll be going home soon and i'll check it out! Thanks!

 

[sdpatt]

There should be a temperature scale on the pressure guage since the pressure of the refrigerant within the system is very dependent upon the ambient temperature. If not, here is a link to the pressure/temerature table for both R-134a and R-12. If the system, its pressure interlocks and compressor clutches are all working properly, too much pressure can reduce the effectiveness of the system just as well as too little pressure.

With the engine off and cool from an overnight rest, you can measure the pressure at either the high or low pressure fittings and compare it to the table at the link provided above. If the ambient air temperature measures between the 10 degree increments, you can interpolate (or approximate) to get a more accurate pressure. The temperatures in the table are the static pressures of the different refrigerants at various temperatures. A pressure much higher or lower than shown in the table will impede the efficiency of the system.

<small>[ June 30, 2003, 02:23 PM: Message edited by: sdpatt ]</small>