amac944

Hey guys,

I have a 1986 944 N/A with a 5 speed with 71k miles on it. I acquired it a month ago or so, and the A/C has never worked.

When I run the cabin air fans and push the A/C button, I do not really hear the compressor kick in at all, but when the car is off, and I push the A/C button on, I do hear a fan running on the front of the car (probably normal, right?). The light on the A/C button also comes on.

I did a little test: I turned the A/C on full blast with recirculate and then looked at the little sight glass on the drier. I didn't see anything at all--no moisture inside, no frost or even bubbles. I felt the lines going into and coming out of the drier, and they did not feel hot or cold--just the temperature they were at before I turned the A/C on.

Where do I look next? I suspect that all of the refrigerant leaked out a long time ago (previous owner of 1.5 years said the A/C never worked for him, either). I also believe I will have to change out all of the seals and perhaps do a r134a conversion.

However, before I do this, is there any way to determine whether my A/C compressor works? Anyone have any thoughts? Thank you so much!

DarylJ

Congratulations. You're par for th course.

Seriosuly....if the compressor doesn't even kick on, chances are good that the low pressure switch isn't tripping, which most likely means that you have no refrigerant in there. Which would be about typical....you probably have a leaking <something> that needs to be found and replaced, the dryer replaced, system evacuated, and recharged.

At that point, you'll like find 4 other things wrong that keep you from having A/C.

Once you figure them all out and fix them, you'll be pissed as how bad the "properly working" A/C actually is.

amac944

AHahahaha.... I don't think I'll be pissed about the poor A/C. I had a Miata for a while (loved it), but the A/C was **** poor.

m73m95

Well, I will tell you 1st thing that you are in for a long and painful fight. There are more of us on here without AC than with.

First off, buy a set of gauges. The r134 gauges will actually work on a 944 because European fittings are the same size at both ends. Harbor freight has a good set for cheap.

Next, check the pressures. A hard number isn't needed at this point, we just want to make sure you have something in the system so you don't ruin your compressor trying to diagnose the problem.

One you have determined there is some refrigerant in the system, you can jump the low pressure switch (with the AC button pressed, and the fan on high, engine running) its under the driver side headlight (pop up the lights, then turn the light switch back to park lights). You can't miss it. Its hooked to the AC pressure line, and has to wires coming out of it. Disconnect the 2 wires, and jump them together. If the AC compress or clicks on then you might get lucky and just have to add some refrigerant (probably freeze 12) and everything will work fine.

Let us know once you have tested the low pressure switch. The road kind of splits from there, and we need to know which way to go.

...... depending on where you live, this might not be a fight worth fighting.....

amac944

Well, what's the worst that could happen? If I toast the compressor, will the pulley seize and screw me over? Or is the worst that can happen is that I end up with no A/C, which is exactly what's going on now?

m73m95

well, if your compressor works, then it MIGHT be an easy fix... why would you want to spend $150 on something that you might not need to buy?

If you are completely out of refrigerant and try to use the system, you'll ruin the compressor in 2min.... for nothing....

75ohm

If you're completely out of refrigerant the system shouldn't even kick the compressor on...

Pull a vac on the system to see if it will hold vac... if not, then you have to find the leak and go from there.

You will need to replace the receiver if the system has been opened and you should probably do it anyway.

Start with the system sanity check first...

DarylJ

Nah...it's not that bad. Lots of 4x4 guys use compressors for air (tires, etc) for years (realistically 10s of hours of use) and they're fine. I just wouldn't jump the low pressure switch and LEAVE it like that if you find out that you aren't getting any cooling.

If the pump was dry and beat up enough to tear itself up over that, it was probably going to do it about 4 hours after you properly recharged the system anyway.

m73m95

I've never seen a 4x4 guy use an AC compressor for that purpose. Especially when a real belt driven air compressor would work twice as good and cost half as much (as a new AC compressor).....

Besides, why spend money you don't have to? Go to harbor freight and buy the $30 set of gauges. That way you can pull a vacuum, and fill the system yourself after you've sealed the leaks.

DarylJ

Who said to use a new AC compressor, and what relevance does it have if you've seen it done or not?

Buying a late 944 is easier and cheaper than doing a dash swap, but Marquito is doing it. Because he wants to and he can. Some things are done for that purpose.

Even a cursor google search turns up some (in this case over the top elaborate) instructions on how to do it:

http://www.la4x4.com/onboardair.htm

Seriously, dude...did you really just put those two sentences together in the context of bypassing the pressure switch (for free) to see if it works or not?

m73m95

D - FENCE
D - FENCE lol

All of this is neither here nor there. I've worked on quite a few 4x4's and I've seen tons of air compressors on them.... not a single AC compressor. I'm sure it would work, but I don't believe it to be the best option. The best option is to go the the scrap yard and steal a belt driven compressor off of an old diesel engine from an old peterbuilt, mack, kenworth, etc truck for $50 --- but who F'in cares?

My point is that buying a set of gauges to check the system are needed. Running the AC system dry won't help anything, and won't give you any information UNLESS YOU HAVE THE GAUGES. The OP wants to diagnose his AC problem, and possibly fix it himself. He cannot do that without gauges. Then while he has the gauges, why not make sure the system isn't dry?

DarylJ

Gauges are not needed to see if the low pressure cut off or the clutch are bad And if you don't have gauges, those are easy and obvious things you can check that simply don't require much of anything for tools.

m73m95

Ok, I give. You win.

My ASE certification, and years as a mechanic/welder don't matter.....

DarylJ

Other people, who's backgrounds you have absolutely no idea of, just might know something different and may have had a different set of experiences than you have. Just because you've done something for a living doesn't mean you know everything and that there is no other way than yours.

I'm done with this back and forth. The OP can decide what way works best for him to proceed, and I'll be happy to offer my non-ASE certified advice. Somehow I've managed to get quite a few A/C system running without having a little patch on my work shirt.

m73m95

Anyone who's ever read any of my posts knows I ask more "what if" questions than anyone. I'm not afraid to say when I don't know something and ask someone else for advice. I've never told anyone on here that I was right, and they were wrong.

I offer the things that I DO KNOW to help when people ask for it. If they want to follow what I say, great. If not, then thats fine too. I have been trained in the proper way to do things as recommended by auto manufacturers. Its true that there are 1,000 ways to do just about everything, but sometimes there's a wrong way. I'll let other people decide "right or wrong" with running any AC compressor dry....