BillyC Posted August 14, 2005 Share Posted August 14, 2005 Does anyone know at what AC high side pressure the condenser fans are set to turn on? My 91LS400 waits until the pressure is well over 300 psi before turning on. Once the fans are on, the pressure immediately drops to 250 psi where I'd like it to be. I am afraid that this excessively high pressure will blow a seal or pop a hose. TIA, BillyC 91LS400 232K miles North Alabama Quote Link to comment Share on other sites More sharing options...
obergc Posted August 14, 2005 Share Posted August 14, 2005 Your car came with R12 refrigerant, this info is from a 93 with R134, your pressure switch may be at a different trip level. But, for a 93 with R134, you should have low speed fan operation if the A/C is on, the compressor clutch is engaged, and the high side pressure is 220psi or higher. If your coolant temp goes above 194F, you should have high speed operation. regardless. This info was taken from the engine cooling section of the shop manual. In the a/c section of the shop manual, t states that if: 1. a/c switch off or on, compressor clutch off, water temp below 181F, the fans should be OFF. 2. water temp above 194F, fans should be on HIGH speed in all cases. 3. A/c switch ON, compressor clutch ENGAGED, water temp below 181F, and HIGH side pressure is 455psi or greater, you should have LOW speed operation. A third reference point in the shop manual on testing of the pressure switch itself indicates that the a/c high pressure switch should operate at 455psi. BTW, the shop manual states normal R134 system pressures should be Low side 22-35psi and High side 199-227psi a/c set to max cool, recirculate selected on controller, blower set to high speed, engine rpm 1500 with ambient temp 86-95F. Maybe someone charged your system without pulling a vacuum on the system first, the manual says that if you have air in the system, you will have see above normal pressures on both the high and low sides, you will have bubbles or foam in the sight glass near the right headlights, and the low side piping will be hot to the touch. Something you might check for. Quote Link to comment Share on other sites More sharing options...
BillyC Posted August 15, 2005 Author Share Posted August 15, 2005 Thanks for the info Curt. If the ac high pressure switch is set for 455 psi on the R12 system as it is on your R134a system, then I guess I don't have to worry about 325 psi. Regards, BillyC 91LS400, 232K miles Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.