SXGT

I was talking to someone about my AC being weird and he suggested i change the filter and that it was under the glove box, or rather inside it when you take it all out.

Is that the cabin air filter? do these cars even have one of those? Is there some filter or anything under there i can inspect?

my AC compressor turns on and off every 10 seconds or so. My gauge shows the suva pressure is enough but the needle keeps moving up and down on the gauge.

1998Slow 'Stang

To my knowledge our cars do not have a cabin air filter and the only sort of "filter" for the AC is the orifice tube that is I believe in the high side piping under the hood. I suppose if that were (theoretically) plugged that could be cause something like that, but I am in no way an AC expert so take my opinion with a grain of salt.

The correct way to diagnose an AC problem with a manifold gauge set...Cliffyk recommends a $50 unit from Harbor Frieght that he has used for quite a while.

timeformiller44

there is no such thing as an A/C filter, that is the cabin air filter which im pretty sure we dont have.

the compressor turning on and off is normal, its cycling, and everything it turns on and off the needles will move on the guages, that is what it is suppose to do, if its cold, dont worry about it, its working correctly, if its warm it leaking out or there is a restriction in the system or its overcharged can be many things and needs to be checked.

cliffyk

Short cycling is often a sign of a low charge. It could also be a problem with the expansion orifice and/or high-side pressure switch, or its being overfilled.

You make reference to "My gauge shows the suva¹ pressure is enough but the needle keeps moving up and down on the gauge.". Is this a real test set or one of those single gauge colour-coded things that comes with a filler kit--and pretends to tell you something by looking only at the low-side pressure?

I suspect the latter, which means you need to get a real gauge and manifold test set. As 1998Slow' said I have been using HF's set for years now; I also have a Mastercool set that cost nearly 4 times as much and works no better.

Once you get a proper test set make sure both valves are closed and connect the blue hose to the low-side port and red hose to the high-side port. First read the static pressure then start the engine and turn the AC on high, blower on high and windows open. Then proceed as shown on this site--one of the best out there without being overly complex.

You need to know the ambient temperature in order to properly determine the proper charge level. Here is a table showing what should be expected:



Here is how to interpret the relationship of the readings:



Like any job having the proper tools is the key to making it easy...


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¹ - In case anyone is wondering SUVA is Dupont's tradename for their Tetrafluoroethane refrigerants such as R-134a; just as Freon was their tradename for Dichlorodifluoromethane refrigerants like R-12.

Many, even professionals, still refer to the refrigerant in contemporary automotive AC systems as Freon however it hasn't been for almost 20 years.

uberstang1

I don't beleive there is a filter, That cylinder canister behind the dash has vacum lines going to it and I beleive is part of the heater control unit.

SXGT

well Hmmm.

can the orifice go bad and need cleaning?

the AC compressor pully is messing with my idle, and i can also hear the engine surgging on the high way from the compressor

cliffyk

You don't clean it, you replace it they are $8 or so from any FLAPS--have you checked the pressures with a real gauge set? Most likely the refrigerant charge is low...

wifes pony

If its cycling every ten seconds, its low on suva! Guaranteed. Why its low?? Easily diagnosed, for a hunnered.

BraMas

Um OK? Is "suva" a new term for R134A? and what is a "hunnered"

cliffyk

SUVA is Dupont's tradename for R-134a, just as Freon was their tradename for R-12. It's kind of funny that as an industry we all called R-12 "Freon" and now call R-134a, "R-134a".

And some still call R-134a "Freon", which it isn't.

"Hunnerd" is how my bubba brother-in-law pronounces "hundred"...