Help with AC

[tdangle]

I rebuilt my AC and charged with R134a. Everything worked good, high side was a little high per the R134 charts, but I understand that is typical of retrofits. Yesterday it was hot. Turned on AC and nothing but hot air. Gauge readings were 31/152. Looks like I lost Freon. I inspected all the connections (new O-Rings everywhere) and don't see any signs of oil which should indicate a leak, I think. How should I proceed to find the leak. (I do have the original compressor which is bone dry around the front)

[leddzepp]

As soon as it gets hot r-134 will not cool in a factory system, the condenser is not efficient enough. I went through this years ago. I tried to warn you...

[tdangle]

Originally Posted by leddzepp

As soon as it gets hot r-134 will not cool in a factory system, the condenser is not efficient enough. I went through this years ago. I tried to warn you...

I didn't ask if it would work, I asked about the best way to find a leak. I read about a lot of people that have 134 in their systems and they seem to be OK with the performance.

[leddzepp]

I doubt you have a leak right now. But a good way to detect one is to spray with some soapy water and look for bubbles. People who say the r134 conversion works "ok" don't live where it hits triple digit temps. Don't believe everything you read, try talking to local people with real experience instead. Eventually r-134 will leak out of the front seal on a factory A6 compressor...my real world experience as well. Again good luck!

[Stocker]

Dumb question but is the compressor actually being switched on, and running (or cycling)?

[F.A.A.benny]

Fill the system with nitrogen. Spray soapy water on all components. Not just the fittings. When you say you rebuilt the system what exactly did you do to warrant calling it a rebuild. A proper rebuild will include, among other things, having leaked check evap and condenser, replaced hoses. The compressor should have a double lip seal installed also. should have no leaks from components other than maybe a leak at a fitting.

[F.A.A.benny]

Originally Posted by Stocker

Dumb question but is the compressor actually being switched on, and running (or cycling)?

In a stock system the compressor is switched on and runs continuously. It should not cycle

[tdangle]

My rebuild consisted of replacing all the hoses and 0-rings and dryer, checking the POA Valve which is at 27 psi (might be a little high) flushing the condenser and evaporator. Made sure the expansion valve bulb is clean and tight on the tubing, new insulating tape. Pressure tested the condenser and evaporator with compressed air. pulled a vacuum for couple hours and then it held the rest of the afternoon (3-4 hrs).

I didn't replace the compressor as it seemed to be holding vacuum. I did drain the oil and refilled with Ester oil before evacuating. Then charged with 3 cans of R134 (36 oz) It seemed to work good for a week. i decided to add a little more to bring it up to 40 oz. Worked even better! Don't know the temp of the air coming out as I don't have a thermometer. I did feel the high side was a little high at 325 and low at 42 about 85 degrees outside. Sat for another week and poof, no more hot air. gauge readings low both sides. I just want to make sure its the compressor leaking before I replace it as I learned along time ago just replacing parts can become quite costly vs only replacing what is really needed.

Stocker: Yes the compressor is turning (first thing I checked)
Leddzepp: I hear what you are saying. I sure didn't want to find R12 fill it and then have it leak only to start over again. I figured if I charged with 134 and it didn't work for me, but held OK, then I would consider trying to find some R12 to refill with. I've looked on CL and all I see is $40 a can or so. needing 5 cans is fairly expensive to test the system with.

[tdangle]

F.A.A Benny: What is a double lip seal? Is this at the front of the compressor behind the clutch or the double connection at the rear?

[demian5]

We chased a leak when we converted my sons 86 to r-134. Turned out it was the actual conversion fitting on the drier that was leaking...

[rsgt]

I always hear Fill the system with nitrogen. Where do you get it? or do you have to take it somewhere.

[F.A.A.benny]

Originally Posted by tdangle

F.A.A Benny: What is a double lip seal? Is this at the front of the compressor behind the clutch or the double connection at the rear?

It's a better shaft seal that goes in the front of the compressor.

[leddzepp]

Where did you purchase your o-rings? The local parts stores only carry metric o-rings, which are NOT the correct sizes (they are close but not the same). Just throwing that out there because I ran into this when I restored mine a few weeks ago. Luckily I had some standard o-rings left over from an older restoration.

[F.A.A.benny]

Originally Posted by rsgt

I always here Fill the system with nitrogen. Where do you get it? or do you have to take it somewhere.

I have a nitrogen cylinder that I use for pressure testing my welds on evaporators and poa valves. You can pick some up at a welding supply store

[davepl]

Take a look at the underside of your hood over where the compressor sits. I did roughly the same as what you did, and mine would hold vacuum for hours, but when running would throw oil off the snout of the compressor, and that's where I lost all my freon.

I can't speak to whether R-134 will work well with the factory condenser, but it does work well enough with a parallel flow. Now would be a good time to do that if you haven't already.

[rkeller411]

What is the recommended setup? Ledzepp what do you suggest? I have factory air that needs to be rebuilt so any recommendations is appreciated.

[davepl]

I'll defer to Ledzepp but just as a point of reference, all I did was the R-134 conversion itself (new fittings, POA adjustment, etc) and then new O-rings, new lines, new compressor (later), and a new (parallel flow) condenser. Works great.

[leddzepp]

Originally Posted by rkeller411

What is the recommended setup? Ledzepp what do you suggest? I have factory air that needs to be rebuilt so any recommendations is appreciated.

This is a list of stuff I bought. I did not replace the condenser or evaporator, I flushed them and pressure checked them prior to charging the system.

NEW A10 compressor, expansion valve, drier/receiver, quart of mineral oil (used with r-12) $325 purchased as a kit at autozone. Lifetime warranty on compressor. $50 rebate promotion during May when I bought it, so really $275

New hose/muffler assembly, liquid line, 3 piece drier hard line kit, insulating tape, interior plastic vent hose kit, small parts, o-rings, $260 from classic industries (were all old air products)

3 cans of r-12 and one 10 oz can of oil charge. I already have it on hand, but when I buy it I usually pay around $10 a can, so $40 there.

[tdangle]

I found one of my fittings a little loose, but nothing for sure as to the source of the leak. It did have a leak as it had lost some of it's charge, as once I added a can of 134 with uv dye, it blew cold again. Really haven't found the source of the leak yet using a black light. the UV dye is certainly messy though. I added a 2nd can and all seems to be working OK, Pressures are close (fan in front of the condenser lowered the high pressure). Air temp at center vent is only about 54 at 90 outside. Looks like I may look for some R12 once I'm sure the system is sealed up tight.

In learning about AC systems, the only thing I don't understand is the POA valve. I found a description that it limits the suction pressure so the evaporator is at the right pressure, but don't understand the calibration of it as to how it relates to the low pressure side of the system. Anybody have a solid understanding of the POA valve.