Understanding some climate control issues... - PeachParts Mercedes-Benz Forum

snookwhaler · #1 10-18-2009, 11:47 AM

I am trying to wrap my head around some climate control issues. During the summer I removed some vacuum pods and plugged the lines to get the A/C really cold.

Now that it is getting cooler, I would like to just fix the ACC. Everything appears to work normally except using the economy button. Pushing that button with the fan on low, high or auto. results in the fan shutting off within about 20 seconds. I then need to run the A/C to get the fan going again. Is this normal?

Also, the heat is working but I wanted to verify a few things. With the car running and the heat set to high (not in detent), the Aux. pump does not run. When I put the heat to full high (in the detent), the Aux. pump runs. The Aux. pump also runs when the defrost button is pushed. Is this normal or abnormal?

Not sure of the condition of the monovalve. But, the heat works, so assuming that is ok.

I just want to be sure everything is functioning before I replace 3 of the vacuum pod diaphragm's.

lietuviai · #2 10-18-2009, 02:58 PM

Pushing one of the A/C buttons along with the EC button will override the A/C. The FSM on the CC shows additional functions are possible when pushing two buttons together.

snookwhaler · #3 10-18-2009, 05:50 PM

Well... Thanks, that helped with the fan running in economy mode. But, I have to "trick it" to get it to run. I have to run the A/C first then push 2 buttons to keep the fan running at any speed.

Then there are some other weird things. I have no heat unless I go to defrost. With defrost and the economy button pushed I"m getting 160 degrees out of the vents. Then I go back to economy and the center button with the dial set to hot (not in the detent) and it gradually cools off. If I go into the detent it gets really hot again (because the Aux. pump is on) but then the fan shuts off.

I don't know.... Either something is broke or I really have no clue how to use the damn thing.

#4 10-18-2009, 05:56 PM

It's probably just a flaky AAC unit, the easiest solution is to replace it with a rebuilt unit:

http://gdl-online.com/begin1.html

my123ca · #5 10-18-2009, 06:09 PM

Mine was like that before i chnaged out the blower. Had to do all sorts of combination to get it started.

The aux. water pump should be running in the defrost mode. Also check the temp sensor and the foam pipe if its still there. The sensor might be giving the wrong information to the ACC

snookwhaler · #6 10-18-2009, 07:21 PM

Quote:

Originally Posted by my123ca

Mine was like that before i chnaged out the blower. Had to do all sorts of combination to get it started.

The aux. water pump should be running in the defrost mode. Also check the temp sensor and the foam pipe if its still there. The sensor might be giving the wrong information to the ACC

Well, I hope its not the "unit".

I replaced the foam pipe. I used a piece of rubber hose and taped it in there months ago. Where exactly is the sensor? I was looking for it when I had the glove box out today. Yes, the Aux. pump works in defrost mode. It gets "hotter than 40 hells" really quick. I checked that with a meter this morning.

Thanks!

toomany MBZ · #7 10-18-2009, 07:30 PM

The sensor is behind the small plastic grille on the dash.
The "units" are a common failure item. You may be able to remove it and correct any cold solders.

#8 10-18-2009, 07:56 PM

Quote:

Originally Posted by toomany MBZ

The sensor is behind the small plastic grille on the dash.
The "units" are a common failure item. You may be able to remove it and correct any cold solders.

The problem is re-soldered AACs are worthless as cores when you need to buy a rebuilt unit.

toomany MBZ · #9 10-18-2009, 10:09 PM

Quote:

Originally Posted by Craig

The problem is re-soldered AACs are worthless as cores when you need to buy a rebuilt unit.

Is true, make your choice.

daw_two · #10 10-18-2009, 10:13 PM

Quote:

Originally Posted by Craig

The problem is re-soldered AACs are worthless as cores when you need to buy a rebuilt unit.

but if you need an unsoldered unit for a core, I bet there's at least one forum member that can help you out.

#11 10-18-2009, 10:35 PM

Quote:

Originally Posted by daw_two

but if you need an unsoldered unit for a core, I bet there's at least one forum member that can help you out.

Very true, hopefully there will be a supply of unmolested ACC and CC cores around for a good long time.

lietuviai · #12 10-21-2009, 08:38 PM

I have to trick mine into running as well. I've given up on wasting anymore money or effort on the system. The A/C system sprung another leak somewhere so the A/C is probably kaput for good now. I'm glad at least the heat works OK but the defroster doesn't really do a good job clearing the fog off the windshield since there's no A/C to dry the air.