Climate Control II - PeachParts Mercedes-Benz Forum

jamesNB · #1 05-07-2009, 11:22 PM

So I have a 1979 300SD with the Climate Control system. Last year I replaced the AC compressor and number of AC parts and it blew ice cold air. Then Winter came and the heater didn't work so I pulled the servo module, connected the heater hoses with some copper tubing, and plugged the little hoses with golf tees. I got cozy warm air.
Now it's getting hot again and I need to get the AC going again. I'm planning to order the electronic replacement from Diesel Giant but I have a couple of questions:
1. The The Diesel Giant replacement the best way to go?
2. Does the kit include everything to replace the entire servo unit?
3. How do I get the AC to work in the meantime? Right now the AC blower doesn't come on. Do I just need to unpulg the golf tees from the lines?
Thanks

kerry · #2 05-07-2009, 11:29 PM

If you search on my name and Servo manual, you'll find a thread with a link to an on-line servo manual which should answer your questions. My recollection is that the AC won't work without the servo in place.
There are threads on here by people who like the digital replacement. The only negative comment I have ever heard was an MB mechanic who didn't like it because it didn't have a troubleshooting manual.

Jeremy5848 · #3 05-08-2009, 12:07 PM

My mechanic replaced an ACC-II servo with an electronic version and the customer was said to be pleased. AFAIK, the only downside is the cost.

leathermang · #4 05-08-2009, 12:16 PM

Quote:

Originally Posted by kerry

The only negative comment I have ever heard was an MB mechanic who didn't like it because it didn't have a troubleshooting manual.

EEEEKKKKKKK!!!!!!!

Seems like question number two ought to be answered by DieselGiant ???

Question number 3 probably implies the use of your regular controls .... but bypassing them for the summer by 'hard, direct ' wiring would be possible...

Jeremy5848 · #5 05-08-2009, 12:35 PM

Agreed. Unless you want to build a manual controller or replace the defunct servo, the simplest way would be to install a couple of hard-wired switches to force the a/c compressor's clutch and the blower to both turn on. I don't know how the flaps work in ACC-II; you might have to do some vacuum plumbing. It would be a crude ON-OFF system and you would have no heat for the occasional cold snap but it should work to at least get you some cooling.

leathermang · #6 05-08-2009, 12:38 PM

LOL, James is here in Central Texas with me and Randy... today we are going to be at MID 90's.... and plenty humid to boot...
He can count on 5 months ( and maybe 7 some years) not having to worry about any of those ' pesky coldfronts' bothering us...
LOLOL

leathermang · #7 05-08-2009, 12:43 PM

I do not agree that is would have to be a crude on off system...
AND, it should be possible to unhook the vacuum control on the flap and WIRE IT... not electrical wire... but CABLE wire it...
like my Type ONE MB AC system uses for most controls.
Would not suggest interfacing with the vacuum system for flap control ... looking at the diagnostics in the MB AC manual for the type 2 and 3 vacuum DASH controls ALONE will make a grown person puke.

jamesNB · #8 05-09-2009, 12:58 AM

Quote:

Originally Posted by leathermang

LOL, James is here in Central Texas with me and Randy... today we are going to be at MID 90's.... and plenty humid to boot...
He can count on 5 months ( and maybe 7 some years) not having to worry about any of those ' pesky coldfronts' bothering us...
LOLOL

Yup, it's getting warmed up. It wasn't bad driving to work at dawn and coming home at dusk, especially with the sunroof open but now the evening commute is getting a little toasty. And with the swine flu going around, I don't like driving through Schertz with the windows down

I read the second thought as count on 5 months (maybe 7 some-odd years) of no cold fronts and I didn't skip a beat.

I just glad we've had some rain.
So, I think the ACC buttons are vacuum controls but this has me thinking maybe one of the hoses came undone when I had the control plate out? I looked at the MB ACC manual and it was confusing. I searched the forum and found a 1970s Chrysler booklet but that didn't help much. The Defrost and Bi-Level settings blow air but it's warm. The Hi and Lo setting do nothing.
Unless someone gives me a compelling reason not to buy the Diesel Giant digital fix, I'm going to order this weekend.

jamesNB · #9 05-09-2009, 01:17 AM

Quote:

Originally Posted by Jeremy5848

Agreed. Unless you want to build a manual controller or replace the defunct servo, the simplest way would be to install a couple of hard-wired switches to force the a/c compressor's clutch and the blower to both turn on. I don't know how the flaps work in ACC-II; you might have to do some vacuum plumbing. It would be a crude ON-OFF system and you would have no heat for the occasional cold snap but it should work to at least get you some cooling.

I don't think my compressor has a clutch; I think it runs all the time if the dash switch is on.

CANDIDE · #10 05-09-2009, 01:22 AM

Quote:

Originally Posted by jamesNB

So I have a 1979 300SD with the Climate Control system. Last year I replaced the AC compressor and number of AC parts and it blew ice cold air. Then Winter came and the heater didn't work so I pulled the servo module, connected the heater hoses with some copper tubing, and plugged the little hoses with golf tees. I got cozy warm air.
Now it's getting hot again and I need to get the AC going again. I'm planning to order the electronic replacement from Diesel Giant but I have a couple of questions:
1. The The Diesel Giant replacement the best way to go?
2. Does the kit include everything to replace the entire servo unit?
3. How do I get the AC to work in the meantime? Right now the AC blower doesn't come on. Do I just need to unpulg the golf tees from the lines?
Thanks

I can't comment on how to get your AC going, but I can tell you what I did to get warm air, and from the center vents, last winter.
If you pull the connector from the monovalve, the heater will be on full and if you turn the temp wheel to MAX Cool, you'll have hot air from the center vents. Easier than golf tees etc. No servo control, but warm air none the less.
Ac, when I get some time I'll diagnose my system. You might want to look at the thread where the poster bypassed much of the AC control via the KLIMA relay.

leathermang · #11 05-09-2009, 08:59 AM

Quote:

Originally Posted by jamesNB

I don't think my compressor has a clutch; I think it runs all the time if the dash switch is on.

I would sure be surprised if a 1979 ANYTHING had a non cycling air conditioner system... this would also mean you had an orifice tube in your car as compared to a TxValve... You need to know what you have before you start trying to fix it...

kerry · #12 05-09-2009, 11:29 AM

I know there's something different about the 79SD AC cycling compared to the later models as I vaguely recollect reading about it when I was working on mine. I think it is that as long as the ACC is on, the compressor is activated or something like that.

As far as Candide's comment goes, the early servo models do not have a monovalve, they are mutually exclusive.

leathermang · #13 05-09-2009, 06:50 PM

I still say I will be VERY surprised if the compressor on his 1979 MB is not the cycling clutch type. Later GM and other cars went to that type system...but nothing in my MB FSM hints at that for MB that early... they went from One , two, and three type AC's.. and would have been much better off jumping from ONE ( like my 1980 240d has ) to a non cycling orifice tube...there would not be the number of AC posts on this forum if they had been kind/smart enough to do that....
Maybe someone was smart enough to change it out on their own ?

jamesNB · #14 05-09-2009, 11:35 PM

Well, it's not a ACC I and I'm not sure what the III looks like but I'm certain it's a ACCII. I replaced the compressor last year with an R4. It ran all the time and the air was ice cold. The expansion valve looks like a valve with some long lines attached; not like a brass block with four connection ports. The system doesn't have a monovalve. Does this help?
What is an orifice tube? Where is it located?

derburger · #15 05-10-2009, 12:30 AM

My 80 300cd with the AutoTemp II and it definitely cycles the compressor on and off. You can order a rebuilt aluminum body servo with a warranty from George Murphy at performance analysis for less than the digital kit if you want to go that route. Last year I bought a used servo for $120 and replaced some vacuum bits and it's been working perfectly. Having clean coolant and removing the servo during a flush definitely helps to keep it from grenading itself but it eventually will due to the engine heat and complexity of the system anyway.