W124 A/C Leaks, Evap Replacement, and more?! - PeachParts Mercedes-Benz Forum

JamesDean · #1 08-21-2014, 06:56 PM

So my a/c system just decided that it no longer wanted to function this morning.

It was working okay yesterday, maybe a bit weak but it was 85+ and typically I don't get awesome cooling when its 85+ and very humid.

Today it did not want to engage the compressor at all on the way to or from work.

I put the gauges on it and got 0 psi on both sizes.

I've got a cheap little sniffer thing but I've not been able to find anything with it. I sent down a can of R134A that I had on the shelf, low side registered 30 PSI or so.

No leaks on the low side hoses, or up near the expansion valve.

I think I'll toss more into it and see if I can sniff any on the high side hoses or near the compressor.

My fear is that its the evaporator. The car's got 290K on it so maybe its time.

The dashboard needs to come out anyway as I've lost 4 of the 7 vacuum circuits (all but one pod).

How much more work is it to replace the evap?
What else should be replaced while the dash is out?

What brands do we trust for these type of parts?

JimFreeh · #2 08-21-2014, 07:00 PM

I replaced the one in my wife's 95 E320 wagon.

Took a couple of weekends, but I wasn't rushing it.

At the time, the car was new enough I didn't have any pod issues, but figured I'd replace them so I wouldn't have to go in again anytime soon.

Pretty much ended up gutting the entire dash area, some people pull the seats, I didn't.

Jim

leathermang · #3 08-21-2014, 07:04 PM

In the archives there are pictures of a student's car in Florida who took out the dash...
I think the flat rate manual lists it as 17 hours....
I hope you find you do not need to take the dash apart..

Which type of AC dash controls do you have :?

I have the paper manual on those...and sold my 81 wagon to keep from having to deal with them... my 1980 has the type one system... pretty basic... but type two and above... I think it is EIGHTY pages of diagnostic procedures...

Of course as an Electrical Engineer you are in a different league than I am.... good luck.

JamesDean · #4 08-21-2014, 08:05 PM

Quote:

Originally Posted by leathermang

In the archives there are pictures of a student's car in Florida who took out the dash...
I think the flat rate manual lists it as 17 hours....
I hope you find you do not need to take the dash apart..

Which type of AC dash controls do you have :?

I have the paper manual on those...and sold my 81 wagon to keep from having to deal with them... my 1980 has the type one system... pretty basic... but type two and above... I think it is EIGHTY pages of diagnostic procedures...

Of course as an Electrical Engineer you are in a different league than I am.... good luck.

This is in my 91 so its got the push button unit and whatnot.

Its not an electrical problem. Compressor spins up when its got enough refrigerant in it.

I decided to just charge it up and see if I could find the leak when it was running/under pressure.

The only place my sniffer thing beeped at was the fitting/coupling that is next to the high side port. I was going to replace the seal on it but I don't have any wrenches that size.

The low side line, the high side line as it went to the compressor, the compressor manifold, the expansion valve were all beep free.

You know I think my shop charges $65/hour or so...

I really don't have that big of a problem sinking $1-2K for a refreshed HVAC system.

I would do it myself but time is short these days and I might be better off spending it doing something else like, cruise control re-work or other electronics repair or maybe relaxing. ha!

My 190E is scheduled to go up Monday for a few things. If the 300D, within the next 2-3 weeks dumps its AC charge completely. I'll call them and see if they can take a look..if they say EVAP then I'll ask how much for that and the HVAC pods. Can't imagine it being more than 3K total.

To be honest, the HVAC is the last thing on this car that needs to be rebuilt. Aside from some minor here and there things everything else is ship shape.

jake12tech · #5 08-21-2014, 09:14 PM

AC Evap job shouldn't be anymore than $2500 MAX. Once the dash is out, it is cake work.

jay_bob · #6 08-21-2014, 09:58 PM

It's not terribly hard to pull a 124 dashboard. The procedure is in the FSM and it really isn't that bad.

Worst parts:
- Getting the steering wheel off. Not necessary but much easier if you do.
- Removing the speaker covers without damaging the dash, you have to pry off the little cover strips to access the screws.
- Getting the two nuts off the studs that marry the center console to the dashboard above the climate control.
- Removing the center vent assembly without breaking it. You have to release the 4 clips at the corners simultaneously.

If you go slow and careful it should take you about 3 or 4 hours.

JimFreeh · #7 08-22-2014, 06:25 AM

Turn on the A/C with a low temp setting and low speed fan.
Run your sniffer at the output of the center vent.
If the evap is leaking, you'll get beeps.

Jim

JamesDean · #8 08-22-2014, 09:00 AM

Quote:

Originally Posted by jay_bob

It's not terribly hard to pull a 124 dashboard. The procedure is in the FSM and it really isn't that bad.

Worst parts:
- Getting the steering wheel off. Not necessary but much easier if you do.
- Removing the speaker covers without damaging the dash, you have to pry off the little cover strips to access the screws.
- Getting the two nuts off the studs that marry the center console to the dashboard above the climate control.
- Removing the center vent assembly without breaking it. You have to release the 4 clips at the corners simultaneously.

If you go slow and careful it should take you about 3 or 4 hours.

My biggest concerns is breaking little things like the speaker covers. I've removed steering wheels before, that is fairly straightforward.
I know I've read some people here have done it within 1-2 hours (GXSR I think). I know book time is like double digits and I was trying to figure out how but to me it does sound like a 3-4 hour job if taking your time. GXSR said the pods take about an hour too. I wonder how much longer it takes to do the evaporator.

With the dash out I could install my remote start system that I bought a year ago! Easy access to..everything.

Quote:

Originally Posted by JimFreeh

Turn on the A/C with a low temp setting and low speed fan.
Run your sniffer at the output of the center vent.
If the evap is leaking, you'll get beeps.

Jim

Initially I didn't think this would reveal anything as my center vent pod and diverter pod are both dead. But I waved the sniffer above the dash, kind of where the TXV is and it beeped quite a bit. I think it is an evap leak, maybe slow. It held charge over night and I had nice A/C on the way to work.

I kind of don't think there is a point in trying a sealant largely because the dash has to come out for me to replace the pods and if that happens well might as well do the evap too.

leathermang · #9 08-22-2014, 09:09 AM

Quote:

Originally Posted by JamesDean

......I kind of don't think there is a point in trying a sealant largely because the dash has to come out for me to replace the pods and if that happens well might as well do the evap too.

Agree totally... and can cause problems.

ds190 · #10 08-22-2014, 09:29 PM

I did this job in 2006 following a very detailed step by step in this forum or benzworld dot org, along with the FSM. The answers are here......if you choose to look.

jay_bob · #11 08-23-2014, 08:16 AM

Also while you're at:

Change the light bulbs in the vent wheels. Yes those little "oreos" have light bulbs to light them up at night. And there is one behind the light switch trim panel, that lights up the legends.

Also check the condition of the aspirator fan on the passenger side. This is what pulls the air flow across the sensor in the dome light for the climate control to get its cabin temperature reference. A hose runs up the passenger side a-pillar. This fan runs whenever the key is on.

jay_bob · #12 08-23-2014, 10:16 AM

The worst part of the whole experience as far as fragile parts is the speaker covers. The strips that cover the screws can get brittle from sun baking. Use a plastic wedge, not a screwdriver, to pry the corner of the strip up. Try to not put any pressure on the dash pad or you will create a little divot. Then gently walk the strip up and you should be able to get it off in one piece.

Once you have the 2 little black screws out the speaker grill lifts out. There is black foam rubber on the back that will be no doubt all crumbly.

Good luck and if you have any questions let me know. I have pulled a 124 dash 3 times, once on the donor for my wagon, the dash that was on my wagon, and then I pulled one out of a parts car to help Vstech.

funola · #13 08-23-2014, 10:45 AM

JamesDean, what kind of R134 sniffer do you have? I need to buy one. Are there good ones and useless ones on Ebay? How to choose?