Climate control buttons - PeachParts Mercedes-Benz Forum

300SD81 · #1 04-07-2007, 06:43 PM

Can someone post the correct order and function for the climate control buttons? I have the one with 5 buttons in the middle, a temp wheel on the left, and 3 fan buttons on the right. They kept popping off when I first got the car and were replaced with junkyard parts.. I think I got them out of order..

toomany MBZ · #2 04-07-2007, 07:10 PM

Do you have an owners manual?

300SD81 · #3 04-07-2007, 07:14 PM

Somewhere, I can't seem to find it anymore..

#4 04-07-2007, 07:16 PM

300SD81 · #5 04-07-2007, 07:35 PM

Close enough?

Now if I can just figure out why the AC compressor comes on in all 4 on settings, even when its set to full heat...

.

#6 04-07-2007, 07:38 PM

Quote:

Originally Posted by 300SD81

Now if I can just figure out why the AC compressor comes on in all 4 on settings, even when its set to full heat...

It's supposed to do that (except on economy), the AC acts as a dehumidifier.

300SD81 · #7 04-07-2007, 07:40 PM

Quote:

Originally Posted by Craig

It's supposed to do that (except on economy), the AC acts as a dehumidifier.

:/ I need a humidifier in the winter... not a dehumidifier.. Might just unplug the compressor after summers over. It comes on in economy (last button before off, with the rectangle??) too though.

#8 04-07-2007, 07:47 PM

I've been to atlanta, you always need a dehumidifier there.

The compressor should not come on with the economy setting (that's what it's for); however, if you really want to defeat the compressor in the winter, just unplug it.

300SD81 · #9 04-07-2007, 07:52 PM

Quote:

Originally Posted by Craig

I've been to atlanta, you always need a dehumidifier there.

I know what you mean.. feels like that most of the time, but it can get pretty dry in the winter sometimes.

Quote:

Originally Posted by Craig

The compressor should not come on with the economy setting (that's what it's for); however, if you really want to defeat the compressor in the winter, just unplug it.

I'm wondering if my CCU is messed up, low fan setting turns the blower off, only the full heat and full cold settings work, in between, and it blows outside air, no matter what the temp is. Are these common problems? Is it hard to pull it? I can grab one next time I hit the junkyard..

carnut · #10 04-07-2007, 07:54 PM

There is something wrong with either the push button unit or the wiring to it. Compressor is OFF in econ. normally. ON in defrost, auto and bi-level. Trust me, you want a dehumidifier in the winter or the windows will want to fog up. Thats why the compressor engages on almost all cars in the defrost mode,to keep moist warm air off the windshield. Diagnose the problem and fix it. A secondary reason the compressor is used is to keep the system functional all year long so seals dont dry up and then leak from lack of use.

#11 04-07-2007, 08:02 PM

Quote:

Originally Posted by 300SD81

I'm wondering if my CCU is messed up, low fan setting turns the blower off, only the full heat and full cold settings work, in between, and it blows outside air, no matter what the temp is. Are these common problems? Is it hard to pull it? I can grab one next time I hit the junkyard..

It does sound like a problem with the CCU, that is very common. You may have trouble finding a good one at the junkyard. A rebuilt ones cost a couple of $100. There are many threads here addressing re-sodering these units when they fail, sometimes that helps.

300SD81 · #12 04-07-2007, 08:09 PM

Is it easy to remove it? Resoldering is fine, but if that doesn't work, I'll just live with it..

#13 04-07-2007, 08:12 PM

Quote:

Originally Posted by 300SD81

Is it easy to remove it? Resoldering is fine, but if that doesn't work, I'll just live with it..

The SD is a little different than my 300D, but I think you need to remove the ashtray to access a couple of screws and it slides out, probably 10 minutes to remove it. Do a search on climate control.

carnut · #14 04-07-2007, 08:52 PM

Remove ash tray assembly. Remove two phillips head screws you now see behind the ash tray, lift out the metal insert disconnecting the wires to the ashtray lighter on the left side. GENTLY pry off wood overlay surrounding push buttons. I used a dull butter knife when the wife was gone! Now you'll see phillips headed screws on either side of the push buttons. Remove these and the surround comes off. Now you'll see screws holding the switch to the opening. Remove these, let the push button switch dangle down and GENTLY remove the multiwire plugs on either side and the three illumination bulbs with wire harness. Be careful, the bulbs have been there for years and wont like to leave! rock them gently back and forth to release them. With the push button unit in your hand, look for any evidence of melted plastic on the case. If none, remove the lid and with a pencil tip soldering iron gently touch each solder connection just enough to remelt it. Put the unit back together, get some di-electric grease to apply to the pins on the sides and reconnect all wiring. If now working, buy a lottery ticket! Rebuilt ones usually have a piece of tape over the lid to verify no one removed the lid because it would tear the tape!

Shorebilly · #15 04-08-2007, 06:11 AM

If you just want to stop the AC Compressor from operating, just remove one of the wires going to the Pressure Switch located on the Receiver/Drier......the Pressure Switch is located on the Receiver/Drier, which is located just behind the passenger side headlights (on an '85 300D).....this pressure switch allows electricity to flow to the AC Compressor Clutch......

If the rest of your AC Klima is working satisfactorily, you could run a toggle switch, to control your AC Compressor......

SB

Note: there are 2 devices on the Receiver/Drier, the other is a Temperature Switch that Controls the Auxiliary Fan......if you are unsure which is the pressure switch, and disconnect this one the Compressor Clutch will engage, but the Aux Fan won't come on......