So I'm driving on the highway and it's 95 degrees and my air conditioning stops working. I think that it's time for a recharge so I stop and hook up the pressure gauge to the low port and get a pressure so high it wouldn't read on the gauge. I didn't put any r134a into the system to avoid overcharging. What's the problem here? Hopefully not my compressor, but my right fan went out a month ago and I haven't gotten around to replacing it. Did my fan not working blow my compressor and that's why theres high pressure on my low pressure side?

 

I hate to tell you disquay, if you have pegged your low side gauge chances are the valves in the compressor are bad allowing high pressure on the suction side.

 

bawls... At least I knew this day was coming when I first bought the car, I had the low and high pressure ports tested and they were only about 30 psi apart so this valve has been going out since day 1.

Thanks for the response, and if anyone else wants to chime in to second that thought, it would really help me buy all the parts to get it done.

 

That was my thought too, was the compressor running when you checked?

 

Compressor isn't running and I knew the compressor stopped working while driving down the highway because when I would turn on the ac, I saw no drop in my acceleration and I could tell the compressor just cut out. On my older car, my compressor stopped working because there was not enough pressure in the system. A simple recharge brought the compressor back to life in that car, but I have never seen where there is such high pressure in the low pressure port. I know that when the compressor isn't on, the high and low pressure are the same, but there is enough pressure in the system to allow the compressor to engage.

More background info. Now I remember after buying the car a year ago, I had a new little ac gauge that I hooked up and the low port read some really high psi. The ac was working ok at that point, but the ac has never worked like it has in other vehicles. I thought it was the blend door, but I've never gotten into figuring that out. The only thing I can think of is that the valves in the compressor have been going out since I bought the car.

Thanks again for anyone who wants to spitball with me. It's better to get a different look at things so I don't overlook some small sensor somewhere.

 

Lets back up a minute, I assumed the compressor was running when you checked the suction side, my grey hair is fogging my thoughts. When a system is not running the pressure is equalized between high and low and the low pressure gauge will be at the top of its scale. On start up you will see the needle come down right away on a good system. If the compressor will not run you have another problem.

I have years of doing A/C in boats and the basics are very simple and it doesn't matter what it is in.

 

clamdigger, I understand that the pressure will be the same between the low and high without the compressor on, but why would the compressor not be turning on if my pressure gauge was maxed out? It seems to me that the compressor is in perfect condition to turn on because it has enough pressure to do so. The only other thing I can think of is that there is some valve that has already failed because my system had a high low side pressure with the compressor on when I purchased the vehicle. This is where I need someone like clamdigger to decipher what's going on in my system.

 

disguay, what clamdigger is saying is when the compressor is running, the pressure on the low pressure side of the system drops. When the compressor is running, the suction side looses some pressure and the high pressure side gains some pressure. This is what pushes the freon through the system. With the compressor not spinning inside (remember, it has a clutch), the two side equalize. All the pressure readings that you use to tell if you need to add more freon are based on the compressor running (so you have a lower pressure than when the system is turned off). If you try to turn on your A/C system and the compressor does not kick on to start compressing the freon, then you have either blown a fuse, had the high pressure switch fail open, the clutch has failed, or you have a wiring problem. Unfortunately, you would need a multimeter to differentiate between a clutch issue, a wiring issue, or a fuse issue. If you need to diagrams, let me know. I'm sure I can help you out there.

I wish I could get my hands on a set o fR-134a gauges to see what is up with my car. I get minor cooling, but nothing to be significant. I want to rule out the freon system before I start digging into the dash to mess with the flappers. I know I have a good charge on the system (I have read the low pressure side and it is up at the proper pressure). I just need to see if the compressor is not compressing enough or if I have a problem with a blockage in the system. May have to spend the money to have a place connect up their gages and give me the information.

 

Well, I think I may have found the problem. It started smelling like burning rubber today so I stopped and investigated. I found a problem exactly like the one in the video. Did I lose my center nut just like a lot of xtype members have? I have to drive 150 miles in the next 30 minutes and would like to know if this is safe or not. I know I might mess up my belt, but the clutch isn't stuck engaged so I don't think it would be a problem.

 

Thermo, if your pressures are correct there is nothing wrong with the compressor or freon circuit. pressure and temp are directly related. There is something else wrong.

 

So I would assume my clutch is shot and I just have to replace the whole compressor still? When I remove my compressor, what do I do with the old r134?

 

disguay, legally speaking, you are supposed to take the car to a shop to have them recover the freon system. After installing the new compressor, you will definitely need to have a shop draw a vacuum on the system. Leaving air inside of the system will hurt the efficiency of the system and only make the car have to work harder to keep you cool in the summer. Once you have a vacuum drawn on the system, then you can add in the recommended amount of freon.

 

I am not an auto mechanic but on the yacht engine driven refrigeration systems I have worked on which use an auto type compressor I have replaced the clutch only.

The problem you have is it takes specialized equipment to "RECOVER" the freon and then evacuate the system after you replace the compressor.

 

Let me throw out another possibility - your AC system could be "over charged" - which the compressor will not engage....

 

Indeed there is an overpressure cutout but have you looked at the video of his compressor clutch?

 

steveinfrance - the OP downloaded that video - I don't believe that's from his vehicle. Not sure if he went under and has the same problem or not. A confirmation would be good here - that would eliminate all the guess work...

 

Fair point, he does say 'exactly like this one' - we'll have to wait for him to tell us.

 

When I say "exactly like this one" I mean that my car's clutch shakes around exactly like the one in the video. I went down there and saw that there was a gap between the pulley and the pressure plate and I've never seen this before. When I touched the pressure plate, it was visibly loose and made a clinking sound just like in the video. Basically, the video illustrates exactly what is happening with my compressor clutch after investigating it. When the car is running, it sounds like this video:
I haven't been able to find just the clutch anywhere? Should I buy a used one and just pull the clutch?

 

OK, for safe measure I would just install a new/rebuilt compressor - remember, let a compitent shop perform the work as they will need to RRR the R134A...

 

abonano, I'm thinking the same thing, but I'm still on a student budget and I'm going to have the shop just remove the r134 so I can install the compressor.

Can I install the compressor with air in the system? I've heard everything from air makes it a little bit warmer to it will screw up your whole system. I don't really ever use my a/c except on the highway, so I don't need it too cold, but I also want to save as much money as I can.