bureau13

Let me tell you, this was not what I wanted to hear. The shop had an electronic leak detector...first, they found a leak...pretty big one...at the low pressure hose. That's really not unexpected, and they rebuild those hoses (something everyone said I would have to do, and tried to weasel out of it...yet AGAIN, "everyone" here turned out to be right). The bad news occurred when he stuck his probe into the center vent and turned on the fan...it detected a pretty good-sized leak...I think. He at first said it might be a false alarm, but it seemed repeatable, so he seemed pretty sure. Now, Roger mentioned to me that these rarely cause problems, and I've seen that stated elsewhere on RL...am I just extremely unlucky? Or is there another more likely explanation for the center vent apparent freon leak?

Speedtoys

Did you see the center vent test?

bureau13

He repeated both tests for me. I should add that I told them I would have to hunt down an evaporator from my "parts sources" and he was OK with that, and said the labor to do everything was $800. Which seemed a little high, until I looked at the dash removal threads to get at this stuff, and now I'm thinking it's quite reasonable. Ugh...

JHowell37

I'd be reluctant to let some random shop tear into the dash of my 928. Others can chime in, but IIRC, those sniffers are rather peculiar, and blowing across the tip of them can cause false positives. So putting it in the vent, turning on the fan, and getting a "high reading" may not really be accurate. Truthfully, I would charge it up as is and see if it holds. The only way I'd dig into that job is if I was losing refrigerant every few days.

joejoe

Perhaps (lets hope) there is ambient air from engine bay (where hose was leaking) that is being pulled in from fresh air vent. Possible if rear engine seal not good or when testing hood is up and pulling air into cab. ?

FredR

I would box it up, run it and see how long it takes to drop off performance wise- you have nothing to lose other than the refrigerant that you are going to lose anyway if there is a leak in the evaporator.

Evaporators can and do fail but not very often [thankfully]. Not sure what the consensus is but I reckon it will take about 2 solid days of effort by someone who knows what they are doing to get that lot out and back in again not to mention splitting the unit to remove the evaporator matrix- I have removed one but never had to install one- quite a job- let's hope it is a false indication. Would not be the first time such has happened with those sniffers- maybe the technician broke wind when sniffing!

Good luck

Fred

FLYVMO

I have had 2 out of 3 units leak. Common denominator: both Florida cars, and I think both sat with an inoperative AC system for quite sometime before they were fixed. Not sure if it qualifies as proper statistics, but that was what I had to deal with.

Cheers!
Carl

j.kenzie@sbcglobal.net

I had a cheap electronic leak detector tell me the same thing about an evaporator. Trouble is, that detector also responds to water vapor, of which there is plenty in the evaporator box. I noticed the detector reacted to the sweat on my hands. I decided to use a fan to blow air across a bowl of water. I stuck the detector in that air current, and it went crazy.
His detector may be better than mine, but I know that not all are reliable.
Good luck,
Dave

bureau13

A little bit of background...the car is in Florida now, but was originally a California car until I acquired it last summer.

I found this shop because a neighbor had them do AC work on his 944, and he was pleased (admittedly, his motivation to go there was that they were cheap, and mine was that they were open on Saturday lol) but the owner and tech seemed to have a bit more 928 knowledge than I would have guessed. He said they used to see them in occasionally when they were a bit newer, and he even had one in with a bullet hole in the evaporator (damn drug dealer cars )

I don't know much about these testers, but it definitely gave off a wail at the low pressure hose leak site, and then in the vent...but I sure would hate to do this if I don't have to.

One other thing, I was there because I had found/fixed a massive leak (munched fuel cooler o-ring) but was still not holding vacuum over several hours. So there's definitely a problem somewhere. I may have him fix the hoses, then fill it and see what happens.

j.kenzie@sbcglobal.net

My leak detector definitely reacted to freon. It did however give a false reading to water vapor. You definitely had a leak, but there are other ways to test for evap leaks. For instance, charge the system, add some UV dye, and check the puddle of water coming out of the evaporator with a UV light.
I would be very tempted to take the advice above, and charge it (with UV dye) and see how it performed and how long it holds its charge. Parts and labor for an evap replacement is probably $2K or more.
Good luck,
Dave

bureau13

Well, they quoted me $800 labor, with me getting a used evaporator from 928International...not sure what that will run...this shop has a reputation for doing decent work cheaply, somehow...and they've been there for years. Still...generally speaking I haven't been letting anyone loose on my car but me. I'm thinking even if the bill is half of that $2K prediction, it might be worth a shot with the dye and charge and see what happens.

Speedtoys

If you go the $800 route, and they dont screw it up, let us all know who it is.

Jetdriver69

Before you agree to the evaporator change, inject UV dye into the system and check for leaks with a black light. The dye will pinpoint any and all leaks.

I was told the same thing, my evaporator was leaking after sticking a sniffer into the center vents.

I went to a AC specialist, used the UV dye and found a substantial leak in the expansion valve. The valve had a crack on the bottom of the fitting hole and the R134 was leaking out there. I had no dye present on the bottom of the car near the vent tube as would be present with an evaporator leak.

The leak wasn't terrible bad as it took about 6 weeks for the AC to lose effectiveness.

The leaky valve was less than 18 months old, but the guy who installed it back then must have torqued the fittings too much and cracked the housing.

Ordered a new valve from Roger and the system has been holding pressure since April.

Even if your evaporator is leaking, you can buy a lot of cans of Walmart R134 WITHOUT leak sealant at $6 a can before you spend $2000 or more to pull the evaporator.

Not to be argumentative, but I don't see how anyone could pull the instrument cluster, dash and R&R the evaporator for $800 labor. Unless he is charging $40 a hour and or has done this job so many times, he can do it in his sleep.

Good luck!!!!

fraggle

Take it home and pull the dash yourself. I did it simply to replace all the orings and expansion valves. It take a lot less than $800. Then you can bench test the evaporator, reseal all the hvac boxes and such and it will be awesome when you're done.

bureau13

I agree that the dye test, after hose replacement, is probably a good thing to do. I do have R-12 still, so it's not that cheap, but still.

I also agree that I SHOULD pull the dash myself...there are a lot of things I need/want to do in that area anyway...including getting a new dash or recovering this one...but I'm not really prepared to do that yet...and that for me anyway is a damn intimidating-looking job lol.

It's funny, initially when he said $800, I thought damn, plus parts, that's expensive. Then I read the thread on it, and said damn, that's cheap! I doubt he's done a lot of these, or any recently, but he did ask me if I had the rear air...right there he demonstrated he knew more about the car than I expected him to know...that bar isn't too high, admittedly...