WTF! 92Q Evaporator and expansion valve failure?

[tkd_q45]

Our 92Q has around 108K on the clock. AC has been slowly getting warm and is now to the point of uselessness. Anyhow I took the Q to a "reputable" shop in Burbank (Lucas AC) - they do quality work. But they told me that I need a new evaporator and expansion valve - quoted me around $1200 for the job ($600 of which is the factory evaporator).

Seems like this is an unusual problem for a Q. I guess I'm a bit suspicious because they told me that my 400e needs a new evaporator as well - this I know because it IS a common problem of W124 Mercedes and you can smell a bit of refridgerant at times.

Anyone know of a reputable AC shop I might get a second opinion from?

Also could one go with a 3rd party evaporator? The guys a Lucas told me that for this car, the facotry part is superior to third party - I know this is NOT true for the Mercedes - Behr makes a better/more robust part.

I guess on the bright side, it (evaporator fix) is well over $1000 LESS than what it costs to do my W124. But being that the Q is R12 I can't simply top off when low like I can with R134.

[Jesda]

I've taken the Q to a whole bunch of shops before finally figuring out the problems.

First, it needed a new compressor, so I grabbed a used one for $80 w/ a bad clutch at a wrecking yard. Swapped the clutch. Charged the system. It works fine. Had a friend do it for $150 including three cans of R12.

Second, a bunch of switches and relays and fuses went bad, so I had that all diagnosed and done at a shop for $215.

Another place only wanted me to use parts they acquired.

Another said it was only the compressor. Had they actually done the diagnostics, they would have known it was more than just the compressor. Then they wanted an arm and left nut for the parts. Of course, when I picked up my car and asked how much to pay for diagnostics they said "Dont worry, its free." Well of course it was free, they didnt do anything.

Third, it needs a new receiver drier. It blows cold, consistently and adequately, but not as cold as it should.

So maybe its something smaller. I very strongly recommend paying for the diagnostics at various shops and finding out for sure whats really wrong. AC repairs can be ridiculously expensive if you let greedy or lazy shops take you for granted.

-Jesda

[Q451990]

I assume the evaporator has a hole? Not entirely uncommon. Q2 had a new one installed shortly before I bought her. They should be able to show you with a halogen leak detector that there's a leak detected there. It's possible to DIY or use a salvage take-out (that's what I did for my truck, but it's 134a). Parts cost is probably about right. Try to find someone who'll let you order parts from Joe (evaporator, o-rings, dryer, etc.) and install them for a flat charge. You might also find someone to evacuate the system for you, DIY the repairs if you're into that sort of thing, and then have it vacuumed and recharged professionally.

Heath

[Q45tech]

Very common when the AC system doesn't get preventative maintenance, owners don't even think about it till it fails. Then it can be $2,000 to restore to as new operating condition as operating in a degraded mode puts stress on the compressor.Evaporator labor is more than the part costs. Changing a heater core takes 10-11 hours.

Evaporators don't have to fail if the system is vacuumed, cleaned, dryer filter changed and recharged at reasonable intervals [every 4 years or 60k].

Many units last 250,000 miles and 14 years.Moisture being molecularly smaller than R12 can pass into the flex hoses while the R12 won't leak out creating acids that eat the aluminum from the inside out.

[DAEDALUS]

Sorry to hear it Tom. The expansion valve might explain the system not taking a charge. If you can save some money by having me evacuate and then recharge the system after getting it fixed please let me know.

[Jberger]

Tom, FWIWI lost my AC to a stuck expansion valve in 98 (on a 90 Q) so it can indeed be a problem.

[rrack]

I had the same problem last summer. The system would not allow a charge. I tried everything.

It's fairly easy to remove the evaporator and expansion valve. Just remove the glove box and get after it. I thought my evaporator had a hole too. Get a shop to pressure test it b4 you buy another. My problem came down to old o-rings, a weak compressor and clogged expansion valve. She's now blowing frost down here in Texas.

Oh btw...I bought an aftermarket evaporator for $160 from a local A/C chain here named Carlisle. It was like putting a square peg in a round hole. I returned it and just put the original back in.

[tkd_q45]

rrack - I did have DAEDALUS try to refil my system. My system wouldn't effectively take a charge. Sounds similar to your problem. Anyhow, did you have anyone evacuate your system before you did your work? How long did it take you?

If it is as easy as you say, why does the AC shop want so much to do it? I realize that half of my costs are in parts, another $100+ is for R12 but that leaves approx. $500 for labor? I did forget to ask about the expansion valve cost - but I'm sure it's not THAT much. The dryer ought to be replaced as well right?

The shop I went to is known for being a bit on the high side. I asked a couple of other mechanics I trust, who know of this shop, and they both said that Lucas AC does do good work but they are expensive.

PS - DAEDADLUS - thanks for your offer of help!

[tkd_q45]

Update: I found a shop in Bellflower (near where I work) and the mechanic said that he would try charging my system w/dye and check it in a week (via UV light). BTW - he didn't detect any leaks via sniffer.

[maxnix]

Update: I found a shop in Bellflower (near where I work) and the mechanic said that he would try charging my system w/dye and check it in a week (via UV light). BTW - he didn't detect any leaks via sniffer.

If your expansion valve only is blocked, he will not detect any leaks.

[DAEDALUS]

Don't forget, I think your system already has dye in it. I didn't check it with UV, but I've never seen bright yellow AC oil either. They're easiest to see at night or in a dark garage. Shoot me an email if you want to borrow a UV light for a bit. Did he go behind the glove box with the sniffer?

[tkd_q45]

maxnix - What would be the symptoms of a blocked expansion valve? My AC does blow cold but not quite as cold as I remember it to when working previously. It does seem to get cooler with speed.

Daedalus - BTW this guy had no problem charging my system. He did say he did some disassembly but I failed to asked him about what exactly he had done.

[maxnix]

maxnix - What would be the symptoms of a blocked expansion valve? My AC does blow cold but not quite as cold as I remember it to when working previously. It does seem to get cooler with speed.

Daedalus - BTW this guy had no problem charging my system. He did say he did some disassembly but I failed to asked him about what exactly he had done.

If he charged by weight after evacuation, hopefully he replaced the drier. A partially clogged drier would reduce its efficiency.

Why would Lucas recommend a new evaporator unless it was leaking, or they knew the expansion valve had failed?__________________Brian1995 Q45 & Q45t

Discover the power of the button!

[tkd_q45]

Manix - I will definitely be replacing the dryer as a preventative matinance step. I think Lucas just likes to make money. They did not propose doing a UV test after a weeks time like the second shop did. Most of the cars you see at Lucas are late model foreign (European) cars getting new evaporators (judging by the amount of cars I saw with disassembled interiors). I don't doubt they do good work, I just think their diagnostic procedure could be more thorough.

[rrack]

My AC does blow cold but not quite as cold as I remember it to when working previously. It does seem to get cooler with speed.

Daedalus - BTW this guy had no problem charging my system. He did say he did some disassembly but I failed to asked him about what exactly he had done.

Sorry for the delay...I've been in court all week....ugh...anyway...

I forgot to add that my dad is certified to work on A/C systems and has a stockpile of r-12 so we had all the evacuation stuff. Look for oily gunk build up at any of the line connections. That's a sure sign of a leak and sometimes a sniffer won't detect them. The o-rings on my dryer were shot along with the expansion valve rings which blew all over the evaporator and glogged it up as well.

I also discovered that the electric fan fuse was blown on mine and full of sticks and leaves. It a green 30 amp (I think) in the fuse box behind the battery. If the condensor isn't being cooled well, it won't charge nor cool properly depending on how hot the outside temperature is.

When I got an estimate to have it all done at the shop, I noticed that the parts pricing was neer double the price than if I bought them from the parts counter at the same place. They claim that the spike in pricing is because they warranty the installed parts. That makde no sense to me so I did it myself.

Oh yeah, be sure to replace the dryer while ur at it.

Hope I helped a lil.

Robert

[natsoundup]

How long did it take you to do your A/C system....and did you have a lift or other special tools?