AC Issue Do I need to shim clutch or recharge?

**RJFMBACPA** · 03-27-2015, 01:41 PM

2001 with 146k miles, I am original owner. Live in South Florida and it has been Summer for at least a month. Almost 2 years ago I had trouble with the AC cycling on and off and figured I need to shim the clutch. My indy mechanic convinced me to try a recharge and sure enough that worked until a few weeks ago. I now have a set of AC gauges and figured I would check the pressures to see why the same problem returned. Unfortunately, my first move was of the bone head variety

. When I put the high pressure gauge on the valve was open, shot r134a everywhere! I was thinking I was probably a little low but after the discharge I certainly was. So I have added some r134a and still get the cycling issue, although not as often. Here are the specs on the gauge readings.

Outside air temp 80 degrees F car off and cool not cold both the high and low side settled at 90 psi

While running at idle at between 80 and 85 degrees F ambient the pressures were L 28-30 and H 175. Air temp from vents was 30 degrees below ambient. I had household fan blowing on evaporator. If I were to increase RPM to 2k-2500 the low side would drop to 20-25 and the compressor would shut off. That was last night. This morning I was able to drive about 40 miles at 80 degrees ambient temp and the AC never went warm. Obviously since I was driving I have no idea what the pressures were today.

From what I have read these pressures look low on both sides. That would lead me to believe that I am low on r134a, but I certainly don't want to overcharge. I have no idea how low I was because I pulled the bone head move to start with. Without doing an evac and recharge is there any way to know if I have a proper charge? What pressures can be expected for this model car in the 80-90 degrees F ambient.

I assume that the compressor is going off because the low side pressure is too low and that shimming wont solve that. Why does the low side drop when RPMs increase? Any thoughts would be greatly appreciated.

**JRL** · 03-27-2015, 03:22 PM

Unfortunately you messed up a it, so either find out exactly how much R134 a P2 takes or have it professionally evapped and recharged (always the better idea but yes, a bit more costly).
I can try to find out for you but it will be Monday.
I do know a P80 (GEN 1) takes exactly 1.63 lbs of freon

Until the accurate amount is in there all you're doing is speculating and wasting your time

**RJFMBACPA** · 03-27-2015, 03:58 PM

I know that this car takes 2.17lbs which is approx. 985 grams. I did not release all of the r134a, but I have no way to know how much was released (probably took me 4-5 sec to get my wits and close the valve). But without knowing how much I had to begin with and how much I released, I am not sure how knowing the capacity will help me now. Short of evac and recharge what can I do with my current knowledge to fix this? Thanks again.

**Scopeman** · 03-27-2015, 05:13 PM

You may also have lost some oil in a forceful partial discharge, as the oil is entrained in the refrigerant. So, you can add a little of the CORRECT oil and some gas, or, take it to a specialist and have it evacuated and properly charged and leak checked. It is a sealed system and really shouldn't loose much. A scattered compressor will cost a lot more!

**troyhyde** · 03-27-2015, 08:49 PM

Get a feeler gauge and check the gap on the clutch. Pretty sure this is your primary problem. Easiest to evacuate the system, remove the compressor, then re-shim on the bench. (you will have the opportunity to put the right amount of refrigerant back in)

I wouldn't obsess over exacting numbers, just get a good clutch gap, put in approximate amount of refrigerant, get on with your air conditioned day. These systems are relatively stable/reliable/choose your preferred term.

**RJFMBACPA** · 04-08-2015, 07:21 AM

Thanks Troy. I got a recommendation from an acquaintance about an AC shop that gives free estimates. Got an estimate of $1k for a new compressor and the whole works. But they did tell me the pressures were "fine". They suggested that the wires inside the compressor come apart as the unit gets hot and poo pooed the magnet as a possibility. I politely told them I would think about it and I tried the zip tie shim this past weekend. I jacked the car up on stands and went through the passenger wheel well. What a PIA!!!! I was able to get one zip tie in and secure. Got a second in, but it was stuck and I just clipped it short. I ran out of time and had to get the car back together. It has been 4 days and about 100 miles or so and the AC has not shut off on my once. I get a temp drop of 15 to 25 degrees. Now that I think it is solved I will go back in and replace the unsecure tie with a full one and squeeze a third one on. So, now that I am fairly confident that the issue is resolved what are your thoughts on pressures? I know you said not to obsess over exact numbers, but that is my personality. What numbers do you think that I should expect to see on a 90 degree day with 75% humidity? That is a typical spring day here in south Florida. Thanks for you time!