Ouch, the person who put that bare wire around the fuse terminals should not be working on cars (or house wiring!) IMHO

I suggest you remove the bare wire, check/replace all of your fuses, repair the damaged wire to the AC dryer temp switch, then start the engine and test to see what electrical consumers and devices work and what does not making a list as you go.

As you can see you are uncovering other problems that may or may not be related, and you need to start fresh at square one so-to-speak.

Post what you find.

Also the wires that got damaged from contact with the pully could not prevent the compressor from running. That circuit simply causes the aux fan to come on at high freon temp.

Acky

Well during the test drive the air coming out of the center vents was cooler, but not cold (note: pressed button to close off outside air during this test). Then I noticed both side vents have warm/hot air coming out of them (noticably hotter than the center vents). Cycled through modes with temp 'knob' set to as cold as I could rotate the 'knob' (potentiometer, variable resistor?) in the blue section:

1. Defroster: blew *extremely* hot air against the windshield
2. top and middle vents: blew cool air out top and middle vents (seemed like fan was on extremely slow speed)
3. just middle vents: blew cool air out middle vents with a bit more gusto

I could switch the temperature setting back and forth between hot and cold and there was a noticable change, but hot was extremely hot and cold was cool.

What is the chance this is related to the duovalve?

10-4 on the wiring. Will clean that up this weekend. So what was the fuse on the blue relay for if not for the AC?

I'm not sure about your model regarding the blue relay. A picture would help as to it's exact location for identification.

My diagram shows the compressor control module for your car at the right side near the fender towards the firewall, not in the fuse panel area.

So is the compressor cycling on and off now (working)?

The blue relay is located behind a green relay in the sealed box behind the fuses, driver side firewall.

I am no longer sure that what I thought was the compressor was the compressor. On the passenger side of the vehcile is a device that the belt seems to spin freely on and the front of the pulley is stationary. On the driver side of the car is a device with a standard pulley on it and hoses that appear to go into the ac system. I always thought the front of the pulley on a compressor had a clutch you could see engage and disengage. But now I'm thinking the device on the passenger side of the car is an AIR device and the driver side is the AC. But if that is true, how do I know that the compressor is engaged? And how do I get the black plastic shield covering the compressor off? The tabs don't seem to want to move at all and I *know* if I try it without some guidance I'll end up breaking it.

I don't remember this much trouble when I swapped the intake manifold and carburator on my 75 stingray. But then again, the only complex and unreliable thing to that car was the vacuum system operated equipment.

Here's pic of relay box behind fuse box:

The compressor is on the driver's side. Check your owner's manual for a diagram of the serpentive belt with identification of all pulleys. Black plastic cover over the compressor doesn't sound right.

Thanks for the directions. Did that. Lost headlights (parking lights were on though). Fuses are on order.

High beams don't work when HB lever is moved and locked forward. However if I pull back on the HB lever the high beams come on. Of course if I hold it back they'll stay on. (this is with the bare wire in place; gotta have headlights)

I popped the computer cable to try and check the wire status (passenger side firewall) for the biodegrading wire issue, but didn't see a way to get past the rubber cover. The black wire coming out of the wire cover seperate of the computer connector was in good condition; no cracking visible and the wire bent without seeming brittle. Put the computer wire back and started the car. The ECL is now clear.

Will post more once fuses are in. At least the car is drivable (glass half full).

So the wiring issue in the fuse box was related only to the headlights (combo switch on column is broken).

Fuses have been replaced. Nothing changed with that. Sometimes it seems like the AC compressor engages; RPM drops a couple hundred then goes back up.

Switching from EC to 'white down arrow' button will increase fan speed, even with the fan already set to full speed.

More air is coming from the center vents than the driver/passenger vents; even less coming from the passenger vent.

This seems like it is either a bad relay or a short in a wire. If it was a relay, is there a way to override it? If so, how?

Thanks.

Bill

Looks like you haven't gotten an answer to your earlier question about the blue relay and its fuse. That blue relay (with a 15A spade fuse on top) and the companion green relay (with a 30A fuse on top) are both for aux fan, not for A/C compressor. The blue relay is for stage 1 fan speed, the green for stage 2 fan speed. As has been mentioned, the relay for A/C compressor is not in the main relay box on the driver side firewall, but on the right side of the firewall behind battery.

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

Just to be clear, you are saying the firewall is in the trunk? Because that is where my battery is. Sorry, couldn't resist.

So the relay should be on the firewall behind where the battery would normally sit? Is it just one relay or is there something that you can tell me specifically to look for?

Thanks again.

LOL. Oops, you got me there. Sometimes when I'm typing on auto-pilot I forget that not everyone has a W124. Right, I'm talking about the electronics compartment, where your OVP and fuel pump relay are also located. May be more in the middle of the firewall than the right. One relay, p/n 002-545-18-05. The older ones have the word " Klima" printed on it.

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

This car does not have a Klima relay, or any relays handling the AC compressor.
The Base Module is the one that sends the 12 volts to the compressor clutch.
I do not know which wire.
Your best bet is to apply 12 volts directly to the clutch and see if it engages. Should not draw more than 4 amps. Another method is to check the resistance of the clutch coil. It should be 2.5 to 4 ohms.

__________________
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

My apologies, pesuazo is correct. Even tho billb said it was for a E420 I mistook it for a 420SEL. Geez, what are my nurses puttin' in my Merlot lately? However, the part about the blue and green aux fan relays is correct.

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

Billb95, did u ever solve your compressor issue. Im dealing with the same issue with my compressor not engaging.

DRICHFL,

No. Took it to a place called 'EuroFix' in Franklin, TN. Which I have to give a plug for because of their excellent service. They gave me a rental car (had only a few thousand miles on it), kept my car overnight to look it over, and then when I came back the next day they explained that their was green dye in the system *and*, worse yet, it was all over the back of the a/c compressor - so it is leaking and can't build pressure enough to engage. They recommended I sell the car and get my stepdaughter a used lexus to take to college. So it will be for sale soon.

Now the best part of their analysis:

1. No charge for the labor
2. No charge for the rental car

They did the work, gave me the rental, gave me all that info and all I was out was my time to go there.

Hope you find the problem quickly and cheaply.

Bill