I have a 1986 Camaro IROC Z. 7 years ago my AC was professionally converted to R134. A few months ago my AC began blowing cool but not cold or warm just cool and I'm not sure if I hear the compressor cycling. I replaced the low pressure switch and noticed no improvements. My AC use to get Ice cold where passengers would complain they were freezing even in the middle of a Florida summer.
I checked my AC a few months back and the Gauge said it was at 35 PSI and in the green zone with the AC running. I was told by a guy at a gas station parking lot the other day that the old GM AC Compressors should be at 55 PSI (Which I believe is in the yellow slightly overcharged zone). He said my system is likely undercharged and not engaging the compressor for this reason. I did some Googling but couldn't find anything. Should I buy a recharge kit and add more?

 

At 35 psi was the compressor actually running? Is the compressor cycling on and off at idle? Probably due for a recharge to some extent.

 

With R-134A it should be around 35 - 40 on the low side and anywhere from 225 to 375 or so on the high side, depending on the ambient temp. With the compressor running the gas line (big one) should sweat heavily.

If it's at 35 with the compressor NOT running, then whoever "professionally" converted, "professionally" took your money WITHOUT fixing all the leaks FIRST, so now you need to "professionally" spend more money. My recommendation would be, FIX THE LEAKS, YOURSELF, then recharge it. Fixing the leaks will probably entail replacing EVERY O-ring in the system and replacing the old rotted-out rubber lines with new "barrier" hose, assembled with REAL A/C hose clamps (NOT the weenie little POSs hanging on cards in the Radiator section at AZ). Hopefully - and of course, we all know how effective a business plan built on "hope" is - the leeeeeeeeeeeeks aren't the compressor itself.

 

In their defense, it ran fine for 7 years with no problems. It was only a few months ago when the AC problems began. I'm beginning to wonder if the compressor is bad. I charged it on the low side to 45-50 PSI and the compressor clutch engaged and began spinning but it still blew cool.

It could be a leak or the compressor is going bad. The compressor seems to vibrate a lot and is making a ton of noise.

 

It wasn't. I recharged it up to 40 and the compressor came on but kept shutting off. I recharged it a little more to 45-50 and it stays spinning while it's on.
However, the air in side is still the same. It still blows cool but not cold. Also the compressor seems to be making a ton of noise and vibrates a bit when it's on. I'm wondering if the compressor is shot and my AC system needs a full overhaul.

 

"Ran fine for 7 years" isn't "proof" of ANYTHING. Could be just DUMB LUCK. I'd agree, they probably didn't EFFF UP anything TOO bad, but that's a LONG WAY from "they did it perfect". For that matter it could just be pure bad fortune. At this point it hardly matters; assigning blame is WORTHLESS; concentrate instead on cleaning up the mess.

If the low side pressure doesn't change while the compressor is running, that means the compressor has failed. Utterly totally completely and irrevocably. Most likely a reed valve. While it's entirely possible to replace one of those on your own, it's not something I'd advise somebody posting this sort of question on the Interwebz to try. Unfortunately when a reed valve fails it sheds LOTS of metal chips into the system, it being a little strip of sheet steel, which disintegrates and disperses itself widely.

Sounds to me like you need a compressor, accumulator/dryer, orifice tube (the Frod orange/red one, such as for a 96 or so Crown Vic), flexible lines, ALL O-rings throughout, and a COMPLETE flush of everything you leave in place (metal lines, condenser, evaporator). Then about 2½ oz of PAG oil in the suction port of the compressor and 3 oz in the accum/dryer. Followed of course by 4 cans of R-134A.

 

Well the low pressure does change when the compressor runs. Before I added the freon it wasn't turning on at all. After I added a little bit it would turn on and off. Now it stays on. I am leaning towards you being right that more than likely the entire system needs an overhall.

However, can my radiator fan not coming on affect AC temps? I have the single electric fan with no fan switch (86 TPI car) and I can't figure out why it's not coming on (I have replaced the fan motor, relay, relay pigtail and even the ECM as well as the CTS). I do plan on wiring in a Hayden fan controller to see if that works.

 

Yes the rad fan not coming on will DRASTICALLY affect the AC operation. Think of AC, instead of something that "generates cold", as a conveyor belt for heat: it takes heat from the cabin air and puts it into the refrigerant in the evaporator, which then carries the heat to the condenser where it is shed into the world at large. If the rad fan is not running, the heat stays in the refrigerant; not only will the AC function very poorly if at all, but also, the pressures in the system can become VERY high.

I don't know the details of the 86 control system; but if the ECM requires a high-pressure signal from the compressor (it would be a switch that operates when there's lots of pressure, specifically, enough to indicate that the system is operating) to tell it that the fan needs to come on, and the system is totally discharged, then the pressure will never go high enough to tell the ECM that it wants the fan.

 

First thing I would do is get a set of good R-134 guages and find out what the high and low pressures are.
You mentioned that you had 35 psi ( I presume it was measured at the low side) which is ok, but 40 would be better. I would vacuum the system down, replace the orifice tube.
The orifice tube could be partially clogged. That could cause the system to be cool, but not cold. Once the orifice tube is replaced, vacuum the system down and recharge.
Recheck the pressures as you charge the system. Also, find out what the low and high pressures are when the system is shut down. Pressures should be the same. That means the system has equalized.
Let us know how everything is once you ave done this.