PeachParts Mercedes-Benz Forum - View Single Post

lrg · #4 06-06-2003, 10:28 PM

Just thinking out loud here but I'd guess you could remove the CCU and look for the valve control, I believe it's toward the right side. First I'd locate the vacuum lines that run to the center vent pods. Then, if possible, try to energize the valve that operates that pod (be careful here, I'd assume that it's a simple 12 volt, low wattage valve but I can't guarantee that.) If it works then try to check the wiring back to the CCU. There's a decent chance that the wire color is the same at the valve end as at one of the plugs that goes into the CCU. First I'd check for continuity from the CCU plug to the plug at the valves. Next, I'd carefully open the back of the plug at the CCU (with it attached to the CCU of course) and try to check to see if any current is running to the valve when you move the temp up and down. Remember the CCU doesn't always act instantiously so give it a chance to work. I've tested some circuits from the back of a plug and usually throughly tape around all the other contacts so as to avoid an inadvertant short. I'd suggest you do the same just to be safe. This is a primative way to try to check things out but it's a start and who knows, maybe you'll get lucky and stumble on an easy fix. Let us know what happens.