not sure what you saw but the one black box is my idle speed control and the other i think the other is the idle control module(?) i pulled that fuel pump relay out so it could be I.D.

earl orchard,
The 85 126 is at the end of the generation 1 cars and the 86 is the beginning of the generation 2. There are a lot of differences in the two electronics.Some changes may have made it into your car, but yours looks like my 84 500SEL. The relay you have pulled out is the fuel pump relay. Also in the fuse block is a "Time delay compressor clutch relay" or something like that. It is located next to the fuel pump relay. It is the second from the rear of the fuse box.

Let me know what you come up with and I will try to help if I can.

Paul

__________________
84 500 SEL (307,xxx miles)

i looked in my fuse box..nothing matches with compessor clutch relay,see pic i pulled fuel relay for clarity ..by the way i replaced the monovale (its was ripped up and the heat didnt work)about 2 months ago and the heat works as it should..i have seen in other threads that a bad monovale will mess with your a.c

Attached Thumbnails

 

earl orchard,

Of the 4 relays in the group, The white or silver one is the A/C Clutch Relay. The black one is the windshield wiper delay relay, the red one is overvoltage protection relay, and I don't remember what the yellow one is.

It may be different from my 500 but it looks exactly the same.

If the clutch is not coming one, the system could be low on freon. If not that check Fuse 10 and Fuse 11.

Next you can try jumping the evaporator temperature switch under the dash just above the gas peddle. It is a little box with 2 wires and a small pipe going into evaporator case. That switch went bad on my car one time.

Next jumper the low pressure switch at the A/C drier behind the left headlight. You want the one that has a blue/green wire and a black/red/green wire.

If you haven't found the problem by now it is time to get the text equipment out.

Let us know.

Paul

__________________
84 500 SEL (307,xxx miles)

ok i checked my fuses and they looked good, i went to check the gas in the system and ran into a hang up,
1 how do i hook my manifold gauges up to my ac in my car?
2 is the large silver one my low side port ?
3 is my high side port the one with the black cap on it ,if so does that cap unscrew ? pull off ?

thanks

Kenny

Attached Thumbnails

 

which is high side which is low side
if high side is the black cap how does it come off ?

Attached Thumbnails

 

First problem is you have R-12 gauges and R-134 fittings on the car. The car has been converted at some time and will require different gauges, or better yet, be converted back to R-12 freon.

You can find a lot of reading on this site and others about problems when these cars are converted to R-134. My 500 Had been converted but never worked very well. I finally flushed out the 134 and it's oil and replaced the necessary parts and recharged the system with R-12 and never looked back.

Sorry to have to tell you that but it is what it is.

Paul

__________________
84 500 SEL (307,xxx miles)

the valve in the pic is the low side, the high side is up front next to the condensor. you can get R134a couplings to work with the hoses you got. you could unscrew that silver R134a fitting, but be careful; i've ran into one not having a valve below that fitting (which will empty your system if you take it off)

__________________
1983 300SD (daily driver)
1991 420SEL (work in progress)
1979 300SD (future replacement for 83 SD)

RIP:
1983 300SD (totalled)
1986 420SEL

thanks for the info now i know what kind of gas is in there ,by not working well i guess you mean i was not very cold ? were there other problems?

Correct, not very cold. Also R-134 will leak out of places that R-12 will not leak from. Don't ask me to explain that, we will need a chemist to do that. I am not familiar with the weather in your part of the world. You may be happy with the 134, but in NC it just doesn't work on a hot day (100F).

Paul

__________________
84 500 SEL (307,xxx miles)

it's mostly because of the condensor; it's designed for R12 and doesn't work very efficiently with R134. some people have retrofitted a parallel flow condensor that works better with R134. i've heard people having good results with Freeze 12, and from my personal experience i have used Envirosafe which worked better than R134a but still not as good as the R12. i now only use R12 in my W126 and W116 because it works the best

__________________
1983 300SD (daily driver)
1991 420SEL (work in progress)
1979 300SD (future replacement for 83 SD)

RIP:
1983 300SD (totalled)
1986 420SEL

Ok I got new r134 gauges and hooked them up and I guess since my compressor does not turn on got a reading of zero lbs on both high and low side
Shoud I try to charge the system to see if that Turns on the compressor or what should I do
Thanks
Kenny

The A/C system is pressurized so you always have pressure even with the compressor not running. If you read 0 then you have no R134 in system. You do not need to charge to turn the compressor on. You could jumper the low pressure switch together at the rec/drier to simulate the system is charged. If your A/C works then the compressor would come on but do not run it for too long, under 1 minute, as there is no lubricant inside the compressor.

Good luck.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

2 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

i would pull vacuum on it first to see if there's a leak

__________________
1983 300SD (daily driver)
1991 420SEL (work in progress)
1979 300SD (future replacement for 83 SD)

RIP:
1983 300SD (totalled)
1986 420SEL

Yeah don't worry about getting the compressor to run because it won't produce any cooling with zero pressure.

__________________
Click here to see the items I have up for auction at EBay

Click here to see a photo album of my '62 Sprite Project Moneypit (Now Sold)