eniac

The low side is attached to the compressor on later cars. Easy to spot once you look under the car. If you car is stock ride height, you can see it by laying on the ground and looking at the compressor between the fender and front of the tire.

surfdog4

thanks..after looking at this and some other forums it appears like early cars had the low side on the compressor, then for a few years they had both ports up near the shock tower but in '87 moved it back to the compressor..nice!

Guess i'll have to crawl under there and see if i need a 90 adaptor.

Thanks again

MM951

Thats me

86 951 Driver

My car's compressor squels when I first turn on the A/C I guess I just need to use some R134a with oil in it to recharge it this time?

Mike C.

Any idea where I might find the hardware to extend the low service port? Several years ago I tried to add some R-12 to the system and it just wasn't possible unless you rotated the compressor down. Of course then you can't run it since the belt is loose. I finally gave up and let the shop do it - I seem to recall they charged it from the hi side with some fancy equipment.

Scott at Team Harco

OK - that is probably me. Except the compressor is questionable.

I followed the procedure described here (and some supporting information). Great write-up by the way.

I flushed the system as best I could. I flushed through the two lines to and from the evaporator. Flushed the condensor and the two small lines to the condensor. I installed new o-rings on all locations. Poured about 4 oz. of PAG oil into the compressor and then hooked up all lines to close the system.

I pulled vacuum for 15 minutes. It held vacuum for at least another 30 minutes at which time I allowed R134a to enter the system through the low-side port.

I got about 88 psi reading on both gauges with the engine off. With the engine running I was still getting 88 psi on the low-side and effectively zero on the high-side. I am guessing the compressor is no good.

Anyone care to help diagnose this? I have almost no experience with A/C systems - but I am starting to learn.

John_AZ

I checked the WSM ---Probably the compressor- Low pressure too high and High pressure too low ITEM #3:



What weight PAG did you put in --the 4 ounces?
Oil should have been disbursed with an ounce in the line from the condenser to the evap, an ounce or so in the condenser (since you flushed) and a couple in the compressor if empty--did you empty the compressor before you added 4 ounces of oil? Too much oil will ruin the compressor.

Is the compressor clutch operating correctly?
What freon are you using?

It could also be a clogged expansion valve.

GL
John

Scott at Team Harco

John,

Thanks for the reply.

I think the oil was 100. I can confirm later today when I get home. I dumped the old oil out of the compressor. There was very little left. It came with the car (from the previous owner), uninstalled.

Somewhere along the way, someone must have tore the compressor off the car on a curb, or something similar. I went through a lot of work repairing a number of things and figured I would now try to put the A/C system back as originally intended. I have been running with an A/C delete bracket for the alternator, after repairing the other broken bits. So I have no history on the compressor, other than it came in a box with the car.

I did not put any oil in anything other than the compressor. Is this bad? Maybe I should have used R134a with oil? I used standard R134a as refrigerant but the system only accepted about one half of a can.

I am worried about the expansion valve. Where is that located? I did not remove it during the flush - since I don't know where it is. So that seems to be a definite possibility for a problem.

Assuming I did not ruin it - it there a way to test the compressor? Also is it possible to check the expansion valve? I'd like to figure out which is the problem before throwing more money at this.

Scott at Team Harco

Forgot to answer the other question. Yes - the A/C compressor clutch is working. I tested this on the bench. It also seems to be working as intended in the car.

John_AZ

The preferred oil is ND-8 Porsche which is PAG-46
PAG-100 is thick.

Pros also prefer to use POE 100 which is a more compatible oil with the remaining oil left in the system.

4 ounces should not have damaged the empty compressor.

If you only got 1/2 can of R134a in there is not enough freon in the system.

Your car should take about 2 cans at least or 80% of the fender R12 capacity.

The expansion valve is under the outside blower motor under the hood.

If you have a late 944/2 the best expansion valve DIY is at the KCWS --free sign up to see pictures

http://www.kcws.org/index.php?showtopic=3972&hl=

Try to put a more R134a in the system.

If you added the R134a High & low valves, did you remove the Schroeder valve from the R12 valve before putting on the R134a valve?

GL
John

Scott at Team Harco

OK - I'm not sure if it was 46 or 100. And now that I think about it - it might have been POE. I'll double check tonight. It was what was on the shelf at the local Autozone. (They're the experts, right? )

I realize half a can of R134a is not enough. It should take most of three cans (based on a technical bulletin - it should be 860 g (30.4 oz)). I figured there were other issues which prevented it from taking even one can.

The car is an 89 S2. Is the expansion valve in the same place?

I installed adapters on the R12 valves. It was already converted at some point. There was a blue tag on the fender over top of the original yellow tag. There was nothing legible on the label. Only the high-side had the adapter, so I bought a conversion kit to retrofit for R134a. Prior to this, though, I replaced three Schroeder valve cores with new ones in case they had developed leaks (one was on the compressor itself). I don't recall if the adapters had valves in them. I am certain that one did not (high side?). Regardless, I did not remove any of the R12 valve cores (other than to replace with new). Where are we going with this?

Thanks for the help so far. With the power of Rennlist - I'll get through this.

John_AZ

I was just checking to see if the R134a conversion kit you used to replace the connections had a Schroeder valve included that can depress the valve stem on the OEM R12 hose/fitting .

Maybe try connecting the freon guage if it has R12 fittings direct to the R12 hoses on the car without R134a adapters. Then try to fill with 134a

John

DarylJ

Sounds like you don't have enough refrigerant in the system to know yet.

You slugged it on start up. You should never put more than 1/3 of the total system capacity into a compressor as a general rule. But that's just a general rule.... It's probably just fine, as the total system oil capacity is pretty low and those compressor are pretty tough (yeah, they are tractor parts - so check far supply places if you need a new one or clutch parts as they may be cheaper than auto parts places).

I also think you need to make sure it's really, really flushed properly. You didn't say how you tried to flush it (as in what you used) but and require only an air compressor. Not knowing what was in it before means that regardless of whether you are going to keep it R-12 (you should) or retrofit it (it will cool quite poorly unless you are doing more than 30 MPH on the kinds of days you actually need AC) means you just don't know what you have as far as oil and residuals in there and what may make a mess of things when mixed. Flush it for real with a proper kit, put 2/3 of the oil in the condenser, 1/3 in the compressor, replace the receiver/drier and immediately pull a vacuum for 30 minutes (if you have a pump that will draw down to at least 30 in).

If you are converting, you want to use PAG 46. I prefer the stuff with dye in it already. Then charge with straight R-134a with nothing else added. Put in as many full cans as you can to reach but not exceed 30 oz, then put your last can on and weigh it with something like a digital kitchen scale. Yeah, the weight will be off with hoses attached and stuff, but try to set it up to you can get an estimate in a place where you can keep the can there. Tare the scale and continue to add until you see the correct amount out of the can in negative ounces on the scale and you know you've charged it properly.

If it doesn't take any more refrigerant and the high side stays high but the low side goes to low (when bypassing the compressor clutch so it's always running) you have a clog, and it's probably the expansion valve.

Scott at Team Harco

Guys - thanks for the help.

I used a can of spray-in flush for the evaporator and the two lines connected to it. I followed the directions and saw a bunch of blackish stuff come blasting out. It ran fairly clean after a while. I then shot compressed air through it to try and get most of the remaining debris out.

For the condensor and the short lines I poured a little a/c cleaner in the lines and shot the stuff out with compressed air. I sloshed more of the stuff around and then blasted it out again. I installed a new receiver/drier after flushing the other parts (not the compressor). I am committed to R134a. I think it's too late to turn back.

I did the vacuum thing with the Harbor Freight special pump (2.5 cfm). I didn't have confidence it it lasting for 30 minutes, so I ran it for 15 minutes. According to the gauge, it was holding more than 28 in of vacuum and it never dropped even after another half hour of sitting.

I'll check on things when I get home and see if I can close out some open questions. Hopefully, it will take more R134a and that will be all there is to it.

DarylJ

That's probably what we call "black death". It's the insides of a compressor.

Whenever you see that you know you need to absolutely positively flush everything properly and almost always replace the expansion valve (or at least remove and clean it).

If you leave ANY of that stuff in there the best case is that it (re)clogs the expansion valve, and the worst case is that it kills your new compressor.

----

Just to add to some of the 3-year old discussion in this thread about drain and fill conversions and not replacing receiver driers and the other things people like to post about "getting away with": This is the end result. It may not happen this year, it may not happen next year, but chances are good it will happen. When things aren't done properly you either make sludge which is hard on the compressor, or leave water in which turns the refrigerant acidic and it starts eating lines, seals, compressors......everything. This manifests in leaks and/or chunks large enough to kill the compressor.

This is one of those jobs you do properly the first time if you expect it to last for more than a year or 3. Whether that's worth it or not is left up to whoever owns the car. I know how I do things for myself and customers.