Automotive Air Conditioning Information Forum

Hello, new here. I'm having a problem, sort of, with the a/c on a '83 El Camino. I bought this car a year ago and immediately replaced the compressor, the accumulator, o-rings and orefice tube.

I had it professionally flushed, vacuumed, oiled and charged and it's been working great for the last year (and still is.)

The problem is, when I first fire off the a/c I get a groaning noise coming from the evaporator area that goes away after 15-30 seconds of operation. I get the same noise (sometimes, but shorter in duration) on shutdown. The noise sounds like a sick dog in heat. It's like something has to equalize after it's running to make the noise go away.

The replacement compressor is a new (not rebuilt) Four Seasons and I can neither feel or hear a vibration coming from it that could transmit itself through the lines. Also, the R-134 sticker under the hood says they put 41 ounces in it.

Thanks for any and all help in solving this issue.

Has the noise been there from the start?
Does it vary depending on fan speed?
Vary with temp setting?

The noise started when I had it charged. I ruled out the blower motor because it also does it when the blower motor is disconnected. Changing the temperature slider doesn't change anything, noise-wise. There is no noise when I change it to heat.

Thanks -

Were you using the same compressor from a year ago and had to have the system recharged recently?

The system is virtually untouched from when I repaired it a year ago, hasn't been recharged. Thanks -

Glad it is not a reman comp. However, we generally have seen 4-squeezins quality to not be up to par, even if new.
I am still suspecting the comp.
Time for some pressure readings.
Pressures (hi and lo, thus using a professional manifold gauge set) should be taken with RPM at 1500 , max fan max cool, recirc, doors open (a true load test), and ambient stated, and center vent temp reported.
Report back

Sorry for the late reply. I will perform this test in the next couple of days and report back. Thanks again.

I'm back. The ambient temperature was 80 degrees with low humidity. I had 40-41 degrees out of the center vent with recirc on, full blast. With the low side valve closed at the manifold my readings were 35 low, 275 high. Thanks -

Your symptoms are a bit baffling.
Since they began immediately upon the recharge, at this point, along with the hi side being a bit hi at 275, you may be overcharged. I would suggest you have the system reclaimed, evacuated, and recharged to spec. The sticker says 41oz but how much did they actually put in? And how much oil?
I would have brought it back to them when the shop first charged it

I've had the same issues on the GM orifice tube systems of that era. You may be slightly overcharged and the orifice tube is the source of the groaning noise.