Dave2500

Hello,
i have a 97 TA

the AC stays engaged at idle and blows relatively cold, and the low side is about 30 psi at 75 degrees.

when i take the idle up to like 1800rpm (like driving) the compressor will cycle and the low side drops to 20 PSI

im not sure if it should be 35 psi at idle speed or at cruising speed (1800 rpm ish)

any idea?

Thank you

hrcslam

You should be checking low AND high side pressures with the engine at about 1500 RPMs. But, if it's cold (which 20 psi should be very cold) and your high side is within it's correct range I wouldn't worry about it.

What is the pressure with the system off (static) and what is the ambient temperature when you took the reading? When you check static pressure you need to let the system sit for a couple hours first to stabilize with ambient temperatures and balance within the system.

warriorcustoms

iTrader: (10)

Ive had more than 1 Master Tech tell Me charge A/C for the RPM your cruisin down the highway!!! My old Firebird was 2100rpm at 70mph cruisin down the freeway... maybe it was 75mph but you get the idea lol

hrcslam

I agree. I cruise at 1500 at 65, 2k at 75. My suburban is about 2k at 75 also. I've always checked pressures at 1500 though, but 2k should work too.

Dave2500

Thank you everyone

i gust got a gauge set today and its 80 outside

at idle it is
38 230 PSI

At 1500 RPM it is 30-35 and 225-270 PSI

it seems that at 1500 rpm when the high side builds to 270 it starts going down and the low side goes up to 35 psi then, the low side starts going down and the high side goes back up to 270 slowly,

the compressor doesnt seem to be kicking off,

is this a good charge over/under charged (the air seems cold)

Stadic is around 110 PSI
Thank you everyone

hrcslam

Static should be around 85psi @ 80°F. Your high side running should be 175-210 psi. Slow pressure fluctuation is normal. Seems over charged.