1998 Jetta O.E. AC compressor is retiring....

Hello fellow diesel enthusiasts,

After having no Air Conditioning for the past few weeks, I have finally had time to swing my car into my local guru as its getting rather toasty in North Texas and its getting to become AC time. After leaving the car with him until he had a chance to diagnose (super busy guy and low on mechanic help), the verdict is in. $1,000+ bill is the decision. He says the AC compressor is toast. He told me the low side pressure was around 10psi with AC on I believe (Haven't gotten to talk to him yet, will tomorrow though.)

I am a full time college student and a full time employee who pays for school and living out of pocket, so a $1000 bill is unfortunately out of the question for me.

I am under the impression that a Sanden compressor, oe expansion valve and oe drier will cost me around $500 not including refrigerant or having a vacuum pulled on the system or the amount of alcohol required to be in me to do the job.

I suppose my question is this. Is there a cheaper, but still effective way of replacing the system? Say I grab a used, but known-working unit off of one of you guys/gals or off a local partout/junk yard and just grab a brand new drier and Expansion valve. Would this be okay to do? Or does anyone have any experience with a non-sanden Ac Compressor that has worked for them? I'd hate to go the Chineesium route, as it hurts to put those sort of parts on my car, but if there is any reputable, non-OE compressors out there that are substantially cheaper, I am open to suggestions!

Thanks for reading,
Adam

The replacement of the compressor and associated parts isn't terribly hard. You might want to consider doing it yourself, and taking it to the guru to evacuate and charge the system.

Some thoughts on this:

Take the alternator out. It makes accessing the compressor much easier.
Use all new o-rings.
People say to use OE VW expansion valve.

Other things:

How long are you going to keep the car? OE Sanden compressors are hard to find. You might consider a lower cost replacement.

There should be some OE compressors in the PnP. I have one that an AC shop tested for me. I will have to add oil and put it on my 97 Jetta.

I believe that the AC compressor are the same for all 4 cylinders (both gas and diesel), so a used one shouldn't be hard to find.

Good luck!

Even if you find a new Sanden or Denso I have a feeling it'll be Chinese. I'm sure that the QC will be better than a no name Chinese part.

Finding a good used compressor is probably the budget way to go. Kzoc's idea is a solid plan.

-Todd

These things (ac compressor) sell fairly cheap when used. Just buy a $50-$100 used one from any ABA 2L engine, they are dime a dozen. head over to the vwvortex mk3 forum for one.

Buy a used ac compressor for $75 shipped, buy a new $35 expansion valve, $10 in o-rings, $50 worth of R134 and you will be up and running for under $200

sometime ago i had bought a used compressor for my mk2, the next year it is what seemed to fail, the problem with this (used parts, in this case a compressor) is the special needs of an A/C system, you cannt just swap out parts. normally youd want a shop to evacuate system, if you have to open system again you ll need a new receiver/dryer. -you need that now as it is, you ll also need oil for compressor, and its best to lube/oil orings,seals on install.

Low side pressure is only half the story. 10 PSI is very low, yes, but was the high side also relatively low? Knowing what the pressure differential was tells you the whole story. It also varies greatly depending on what ambient temperature is.

Also, FWIW, most Sanden compressors, their main modes of failure are either the electromagnet for the clutch itself (easy to test and verify) or the internal valve that helps regulate the variable displacement portion of the pump is no longer working very well. You can get a new valve from Polarbear Inc, discharge the refrigerant, unbolt the back half of the compressor, remove the plate with the reed valves and the refrigerant control valve, unbolt the valve, bolt the new one in place ensuring that the reed valves and their limiters are still lined up correctly in the process, re-install back into the compressor and reinstall the back casing of the compressor, pull a vacuum to it then re-charge the system.

You'd be amazed at how well an old Sanden compressor works when you replace the refrigerant control valve. And given that, as has been pointed out, the aftermarket options are very hit or miss, rebuilding an original Sanden unit is often times a far better, longer-lived fix than a new aftermarket unit.

I did exactly that for a local TDIClub member here a few weeks ago... I was measuring 39 F out of the vents when we were done.

I've never had a problem swapping ac parts out, but then again I use freon with oil and leak detection dye. Its a little more expensive but worth it.

I believe my compressor is going out as well - do these symptoms fit the bill?

It takes forever for my AC to get cold. If it's over 80 degrees outside, my AC temp won't get below 60. That is, unless I floor it and get to around 3k RPM for a couple seconds, then my temp will get down to a chilly 40 degrees. (as per the thermometer in my vent) I had somebody "recharge" my system a couple months ago and he said the pressure was really high, but it seemed as though there were a restriction of some sort. I have a used compressor from a 2.0 Cabrio ready to go in.

Need to get a gauge set on it. You may get away with topping off.

Yes, many will say it's mandatory to weigh the charge in, but I call bs. I've been topping my system off for years and get in the 50°s on speed 4. Could I possibly get a few degrees better...? Likely, but it's not worth the aggravation to me.

What was the pressure when "really high"?

-Todd

Well, it was an actual shop, so I trust what he said. Told me it was like 175 PSI.

If that's on the high side, that's low. Around 30/225 is average.

-Todd

Maybe he said it was more like 275. I just recall him saying it was normally around x25-50, but it was up to x75ish.

Well, with the way these mechanical variable displacement deals work, it should keep the low side between 25-35 PSI no matter what the high side is doing/what the charge level is. The high side can vary wildly depending on what the temperature is and charge level.

If the low side is 40 PSI or more and the high side isn't quite getting as high as maybe it should for the given temperature, you'd be surprised at how effective it is to replace the refrigerant control valve inside the compressor... or just get a new Sanden compressor altogether.

When these systems are right, low 40s F at the vents should be expected on a hot day.

I'm gonna bump this one, considering I already replied in it previously. I've been doing a lot of reading and learning over the last few days, so I'm just going to state everything I know.

*AC still struggles to ever get below 60, even with recirculating the air.

*I was prompted to test the compressor clutch the other day when the compressor stopped spinning in the middle of the day. I was able to jump it and regain my AC temporarily

*The compressor will very rarely made kind of a whining noise. I know it's the compressor because I can kill the AC switch and it will stop.

*I put a little more freon in the system yesterday, and got these readings:
At rest - low: 105 High: 145
Running - low: 56 High: 195
After some more freon - low: 50 High: 225

*Today I wired everything back up as it was in order to test the low pressure switch, but it's working as it should now. I'm guessing adding more freon was the right call.

*My car just rolled over 218k miles. I do run the AC a lot, whether it's to cool the air or just dry it out.


Right now I'm leaning toward rebuilding the back end of the compressor and replacing the dryer. Taking it to a shop to discharge the system and doing the work myself.

I have a low mile spare a/c compressor leftover from my AHU corrado I'll sell you for $60 shipped.

G60ING said:

I have a low mile spare a/c compressor leftover from my AHU corrado I'll sell you for $60 shipped.

Click to expand...

Thanks, I'll keep that in mind. Hopefully I can snag it soon.