legacycentral bbs

I bought the car six months ago. The AC was not working when I got it and has not been working for an unknown period of time. When I turn it on the compressor turns on, doesn't make any funny noises, and seems to be working fine, but the air doesn't cool off.

I don't have a garage and I know VERY little about AC systems, so I decided to pay a mechanic to recharge or retrofit. After searching for a while, it turned out the cheapest option was to take it to the local dealership and have them retrofit it to R134. I took it in on Tuesday while I was working.

They called me to tell me they were done but it still wasn't working. They did the retrofit and everything went fine. They charged the system and said it was holding the charge just fine and not leaking as far as they could see, but it still does not blow cold air. The invoice that I got back says "PROBABLE BLOCK IN A/C LINE, FURTHER DIAGNOSIS NEEDED".

As far as I can tell, all they did was replace O-rings, valves, oil, and refrigerant. They did NOT change the receiver/dryer. I took it to a mechanic friend for advice today and he recommended doing this, and then tonight I've been reading over old threads again and have seen this listed as an important part of the process.

Could the old receiver be my main or only problem? Or is there some other diagnostic method that would be better?

It is indeed important to replace the receiver/drier, but failure to do so will not prevent the system from working (temporarily). It will only hurt the longevity of the system. Yes, in my opinion a retrofit (and pretty much any A/C work) should be include a flush and a new receiver/drier.

If the compressor turns on, then there is a refrigerant charge in the system, though. This may be why the shop decided not to replace the receiver/drier -- if the system was already charged then it's less necessary than it is if the system was discharged. This is kind of a sticky point though. If they knew there was refrigerant in the system, and they knew the system wasn't cooling, then they should have known that simply changing the refrigerant to R134a wouldn't have fixed the problem, unless they had no means of measuring the R12 pressure, in which case they might have assumed there was only the tiniest bit of R12 in there. In any case, I would have hoped they would have discussed that with you before agreeing to take your money. Oh well.

So why is a running compressor with refrigerant not cooling your car? Here are some possibilities:

A) One possibility is a faulty compressor like the one that came on my car -- it turned freely but wouldn't actually compress anything.

B) Another possibility is a clog in one of the lines.

C) Or the expansion valve is malfunctioning.

D) Or maybe the condenser is covered with leaves or something.

(A) would show up as high and low side readings both staying at about the vapor pressure of the refrigerant at whatever the ambient temperature is -- somewhere around 80 psi.

(B) would show up as the low side readings coming up lower than they should. Normally you expect somewhere between 20 and 30 psi if things are working correctly.

(C) would show up the same as (B) if the valve is sticking closed, or would show up as a high reading on the low side if the valve is sticking open.

(D) would show up as a high reading on the high side. Normally you expect to see about 200-250 psi on the high pressure side.

So the million-dollar question is: what do they mean by "further diagnosis?" Do they mean checking the pressures (which they should already have done anyway) or do they mean they already checked the pressures and found situation B and now would need to check each line individually?

A clog seems unlikely if the compressor has always been working correctly. But if it is a clog, a flush might clean it out. In my opinion a bad compressor seems more likely, but for that to slip past these mechanics they would have had to never checked the pressures, which seems ridiculous. So I don't know.

I'm not entirely sure what to think about the mechanics. It is a reputable dealership but I am not impressed with thier performance so far. I'm beginning to think that the answer to the million-dollar question is just a way to get more money out of me, because they told me on the phone that it could potentially take two more hours of labor to isolate the problem, plus whatever it would cost to buy the new part and install it. They had already left for the day when I picked the car up and I haven't had a chance to go back and talk to them yet.

So just to clarify things, since I'm not very familiar with the A/C system: I'm assuming "high side" and "low side" refer to the input and output side of the compressor, correct? And which side should be which? If I remember right, the coolant comes directly from the condensor to the compressor (I'm guessing this is the low side) and is then pumped to the receiver (high side)?

Where is the expansion valve located in the system? I looked at the service manual scans but couldn't find A/C in them.

It sounds to me like I definitely need to get the car hooked up to some pressure gauges, either at the dealer or somewhere else. Also, I was reading about how to check the compressor (removing it and putting your finger over the hole), but that presents a problem since the system is fully charged now. I guess I will have to have them remove the coolant as well.

Thanks for the help!

The entire system is divided into two sides. The high pressure side goes from the discharge port (outlet) of the compressor to the inlet of the expansion valve. The low pressure side goes from the outlet of the expansion valve to the suction port (inlet) of the compressor.

The substance in the system is called refrigerant; it is not coolant.

The overall layout of the system is as follows:

Compressor -> Condenser -> Receiver/Drier -> Expansion Valve -> Evaporator -> Compressor again

I have not personally examined it, but the expansion valve is mounted somewhere on or near the evaporator core. It attaches to both the inlet and the outlet -- the refrigerant flows through thevalve before it enters the evaporator, and then flows past a the valve's temperature sensing device as it leaves the evaporator.

Yes, you can do a very basic compressor check by turning it by hand and seeing if it pressurizes the discharge port and depressurizes the suction port. But, yes, you do need the system discharged first.

There's actually a good bit of air conditioning repair info on the board. In particular, I and Josh (Legacy777) have made several useful posts that you might want to search for and read through. You might consider doing this yourself; the requisite equipment pays for itself pretty quickly.

Here are some pictures of the a/c system

http://www.main.experiencetherave.com:8 ... es/acevap/

http://www.main.experiencetherave.com:8 ... ges/accomp

The expansion valve is in the evap box, and can be seen in those pics.

I've been reading through old threads about AC, I mainly needed clarification on what parts were what.

I am definitely considering doing this myself from here on out, the main problem is that I don't have a good place to work on the car (no garage and I'm not technically allowed to do any work in the parking lot at my apartment complex). But I'm a little unclear on what equipment I need. I read back and found that Josh bought a JC Whitney vacuum pump, which is listed on their site right now for $229. It seems to me that I could take the car to a shop and have it discharged and then recharged later for considerably cheaper than that.

Other than the actual discharge and charging I'm sure I can do any parts replacement myself. I think at this point I will go find a shop that can give me some pressure readings and then decide where to go from there.

I made a vacuum pump for much less than that out of two used refrigerator compressor motors, some hose, some clamps, and a few fittings.

I should also point out that Harbor Freight actually has a manifold gauge set on sale for only $40 right now, which is a steal. A steal!

You do need an air compressor and blowgun, too, though, and maybe it doesn't make too much sense to buy a compressor just for this job. However, if you're serious about mechanical work at all though you might consider buying a little one just to have.

Actually I have a compressor already, originally used for woodworking but usable for this, it's just not terribly high capacity.

I think I'm going to try and find a shop that will do a free pressure check for me first, and then see what kind of money I'm looking at.

OK, I went back to the dealership and got more information.

The retrofit kit they used includes the following:

- new fittings
- new valves
- new O-rings
- new oil
- new refrigerant

They did evacuate it for something like half an hour before beginning the process, so it SHOULD have removed all the R12 and old oil.

I also got them to hook the pressure gauges back up. As of this morning, the high side reads 90psi and the low side reads 80psi. The tech there told me he thinks these readings are normal, and also said again he thinks there is a clog somewhere. He didn't give any specific evidence to back this up.

Based on Vikash's list above, the closest match is a faulty compressor. So it sounds to me like the next best step would be to evacuate the system and remove the compressor to test it by hand.

Evacuation doesn't remove oil. To change the oil you have to replace the receiver/drier, remove the compressor and drain it, and flush the remainder of the system.

The purpose of evacuation is to ensure the system is empty of contaminants, the most important of which is moisture.

Evacuation also gives you the opportunity to leak-test the system by checking that it holds a vacuum even when you shut off the vacuum pump.

The tech doesn't know what he's talking about. While it's possible there's a clog, those numbers could never be considered normal.

I agree with your diagnosis of the compressor and with your idea about the next step.

OK, now I just have to get the system discharged. The mechanic I would normally go to for quick stuff like that won't do it because it might contaminate his machine.

Why would it contaminate his machine? You've got fresh R134a.

He is concerned that it may not only be fresh R134a, but that it may also have leftover R12 or incompatible oil mixed in. From what you've said, it sounds like he's right to be skeptical. The receiver dryer was not replaced and the compressor doesn't look like it was removed either. And from his diagnosis of the numbers, I'm not inclined to trust the tech at the dealership on much at all.

So here's another question for you: if he didn't replace anything and didn't remove the compressor, there's a good chance he didn't remove all the old oil. If that is the case, would that still cause a problem even if I replace the compressor?

There's no R12 in there. Even a minute or two of evacuation would ensure that.

And like I said, evacuation doesn't remove oil (unless you throw the valve on the gauge manifold open instead of opening it gradually, in which case a little bit will come out).

So your mechanic really needs not worry. If he discharges your system properly all he'll get is some barely-used R-134a.

It sounds like the dealership just used one of those off-the-shelf Interdynamics kits or something for the retrofit. They generally use polyol ester oil which does not react badly with mineral oil, so the old oil doesn't really cause any harm sitting around in the system. However, we can't be sure they put quite enough ester oil in the system, since it can be hard to get it all in with the ghetto kits that include the oil in the refrigerant charge canisters.

The amount of time it takes to replace a compressor is long enough to significantly contaminate a receiver/drier, so in my opinion you're going to have to replace the receiver/drier. Given that, it will be a minimal amount of further effort to flush the remainder of the system, so I think that's what you should do. That way there won't be any oil except the measured amount you put in the new receiver/drier and in the replacement compressor. As a bonus, the flush should reveal and/or resolve any clogs.

I'll check with him again about evacuating the system, then... when I talked to him I was asking about diagnosing and fixing all at once and he didn't want to work on a retrofit system in general. He's older and very set in his ways so I doubt he'll change his mind, but I may as well ask.

I think it would probably be best to change the reciever/dryer anyway, from the sound of it. As far as flushing the system, are you talking about using aerosol brake cleaner and compressed air? I read about that process in an earlier post.

Well, good luck convincing him.

Yes, you can use brake cleaner to flush. It'll help if you can make some kind of doohickey to allow the brake cleaner to enter more forcefully, like out of a rubber stopper. Some commercially sold aerosol flushes come with a thing like this. No matter what flush you use you do need to blow the system out with compressed air afterwards.

OK, I'll try that. I'm guessing it'll be a couple of weeks before I can get to it though. Thanks for the help.

Other option for discharging....which probably isn't the best, but does work.....disconnect one of the fittings on the compressor, walk away, and come back when it stops hissing.

To provide more information about that idea:

You should know that you can be fined 25 grand for venting refrigerant to the atmosphere, and someone who reports you can be given a 10 grand reward. R-134a is a lot less harmful to the environment than R-12, but it's still a greenhouse gas.

Also, if you were to hypothetically do it, be careful; the rapidly vaporizing refrigerant is cold enough to give you frostbite.

Refrigerant vented this way will carry some oil out with it since it is likely to vent forcefully, so somehow you'd have to take that into account. If you're flushing the system anyway then that doesn't really matter.

If you have a vacuum pump with an outlet as well as an inlet on it, it's pretty easy to properly discharge the system; you just need to attach an appropriate tank to the outlet and evacuate the system into it. Tanks sold for propane are legal for this use (but you'll want to use a new one), and you can then sell the refrigerant to a recycler.

lol, ok, I'll keep both those things in mind.

Just to make sure, the Calsonic compressor from the EJ22 turbo is the same as from the non-turbo, right?

compressor on ebay

Yes. Well, even if it's not, it's interchangeable.

There are two cars at the local u-pull-it with compressors that *look* virtually brand new (I know this doesn't necessarily mean much), so I disconnected the lines on both of them to test them to see if they still work before I buy. I thought I understood the testing process, but neither of them gave me any results even though they looked good, so I want to make sure I understand how to test them before I give up entirely on them.



Here's my understanding so far, based on watching the compressor that's in my car now: Part B turns freely in a clockwise direction with the accessory belt at all times when the engine is running. Part A is the clutch, which doesn't turn at all until you turn AC on, at which point A locks in with B and also turns clockwise, at the same speed. To test it, I put my finger over one of the holes from the lines (off the screen on top right of the picture) and turn part A clockwise a few times, and I should feel pressure or vacuum, depending on which hole I've covered. Switch my finger to the other hole and turn a few more times and I should feel the opposite.

Is this correct? Do I need to be turning part A fast? Do I need to turn part B along with part A (I tried this but didn't notice a difference)? Am I doing something completely wrong?

It's really quite hard to test the compressor, but what you're doing is an ok way to get a feel if it's even working at all.

The biggest issue you should concern yourself with is whether there is metal flakes in the oil when you drain it. However it's a little difficult to determine that until it's removed.

I think it's safe to say that my compressor isn't working at all. Mainly I don't want to buy another one that's also not working.

So if I feel absolutely nothing when I do the test the way I just described it, that means the compressor is bad and I shouldn't buy it, correct?