heater regulating valve leaking - PeachParts Mercedes-Benz Forum

kerry · #1 10-28-2002, 08:40 PM

1977 300d--The heater regulating valve is leaking out the bottom. (The device next to the A/C compressor with heater hoses, vacuum lines and electric wires coming into it--an awful Rube Goldberg looking kind of contraption) Do I need to replace the whole thing or are there gaskets or diaphragms in there that can be replaced? What is the exact name of the part? I can't seem to find it listed in Fastlane.

Billybob · #2 10-28-2002, 09:01 PM

I think the proper nomenclature is Automatic Climate Control Servo or something pretty close to that! Basically a collection of motorized valves and feedback devices that are controlled from the dash settings. I do not have direct knowledge but I have read threads pertaining to its design and function so I’m sure someone with actual experience will have more specific to offer. Try a search under “ACC Servo” Good luck!

#3 10-28-2002, 09:29 PM

I think they make rebuild kits for them, and new ones can be bought for under $400. You can get them at wrecking yards for a lot less, but there can be the problem of getting one that is in bad condition. Mine has a slow leak, but it has been that for a while, but it still seems to be functioning. I am just waiting for the leak to get really bad or for the whole unit to fail and stuck shut. I am doing this because I don't want to spend the time to search for a used one in good condition, and I don't want to spend the money on a new one, and I don't want to spend the time to pull it out and rebuild it. I am hoping that it will last though the winter, and I might get around to it this summer.

GermanStar · #4 10-28-2002, 09:46 PM

The repair kits are pretty useless most of the time and new servos are basically no longer available (tho anything can be had for a price -- way over $400). The best way to go at this point is with a rebuilt aluminum unit. They're widely available and much cheaper than the new ones.

Ron
http://germanstar.net

kerry · #5 10-28-2002, 10:17 PM

Where would I find a rebuilt aluminum unit?

dieseldude · #6 10-28-2002, 10:45 PM

Don't see why you couldn't find one here at FastLane Kerry. Make sure to ask (if it doesn't say) for the aluminium model. The metal body is much less prone to cracking (as the original plastic ones are prone to), thus letting water/codensation in, and probably causing the failure you're seeing now.

if Fastlane doesn't have the servo, I know Randy Steele at european Parts Specialists does. www.epsparts.com

Regards,
- Ryan

kerry · #7 10-29-2002, 01:56 PM

I know some people bypass the servo by joining the hoses underneath the servo rather than going through the servo. Does anyone know the ramifications of this fix? What happens to the temperature sensing switch that prohibits the blower from operating until the coolant is warm. Won't that stop the blower from operating at all? Will it cause any further damage to other components of the climate control system?

#8 10-29-2002, 02:55 PM

I have a 78 300D that the servo cracked and gave out on. I was
going to locate a used assembly for it. So far none available. Have not exhuasted every place yet, but some of what I am reading here put that in doubt.
I did route the hoses around the servo. Easy enough to pull the servo out and run a couple of lengths of pipe between the hose ends. This does work only on the defrost setting though. The other settings will not blow air with the servo out of the loop.

kerry · #9 10-29-2002, 03:03 PM

Have you tried 'fooling' the coolant temperature sensor by jumping the wires to obtain additional heater functions?

#10 10-29-2002, 05:16 PM

I ain't that bright. I suppose that could be done. Even gave it a thought. Problem is I was sure I would come up with a replacement by now, so just continue to use the defrost button.
I sent an e mail to epsparts.com asking about the aluminum replacement. Will post a follow up here.

kerry · #11 10-29-2002, 08:11 PM

I talked to Randy at epsparts and he has rebuilt aluminum servos for 289 plus a 125 core charge refunded when he gets the core. He has one new plastic servo for 595.

Billybob · #12 10-29-2002, 08:38 PM

http://www.peachparts.com/shopforum/showthread.php?threadid=36410

Repair info?

#13 10-30-2002, 11:57 AM

I read through that thread. I looked at the servo again last night and I still doubt it will go back together once it is torn apart. Big cracks in three places. I had started to dismantle it a few weeks ago. Insides did not look to good either.
I am thinking to go with the aluminum rebuild for $289.00. Has anyone had any experience with this?

kerry · #14 10-30-2002, 01:15 PM

I just ordered one from Randy. I'll let you know what happens.

#15 11-03-2002, 02:48 PM

I looked at my A/C servo again yesterday and I found that it is leaking from one of the hoses. What type of hose should I use for this, should I try and get OEM type hose, or should I get some bulk hose from my local parts store. I know they make hose kits for these, but I forgot who sells them.