W124 400E AC not working after heat exchanger change.

[Sam]

Hello, i changed heat exchanger to My w124 400e because of leak now the whole Heating system is not working.

Red Light in the recirculation switch is blinking all the time and the blower wont even start. It wont respond to any buttons on the control panel.

So its on fault Mode.

What went wrong?

Tried to pull codes with blink reader and Star with no luck. (I think that its not even possible to get codes from the acc?)

 

[gsxr]

Fault codes are not available from the ACC system via Star/SDS. You must use a hand-held blink code reader to pull codes.

Have you tried a different pushbutton control unit? If you cannot read codes with the blink reader, the control unit may have failed.

 

[Sam]

Fault codes are not available from the ACC system via Star/SDS. You must use a hand-held blink code reader to pull codes.

Have you tried a different pushbutton control unit? If you cannot read codes with the blink reader, the control unit may have failed.

Yeah it seems like there were no ac control unit on when checking with Star.

The blink reader is home made but i have tried it earlier to pin 16 and never got anything out off that one.

When i plug the test wire to pin 16 the led illuminates all the time only not so bright and when i push the button it doesnt start to blink, not even once??

It works on all the rest off the pins and my acc worked well until this (only leaking freons In couple of months)

 

[Sam]

Am i all alone with this issue?

Today i bought a other Ac control panel but it does the same thing...

 

[gsxr]

This is a long shot, but try disconnecting the auxiliary coolant pump in the engine compartment... see if there is any change. If there is a short-circuit at the pump, it may send the control unit into a "safe mode".

 

[Sam]

This is a long shot, but try disconnecting the auxiliary coolant pump in the engine compartment... see if there is any change. If there is a short-circuit at the pump, it may send the control unit into a "safe mode".

I think i tried that allready?
Maybe have to do it again.
I pulled several connectors off just to try with no luck.

Any wiring diagram available?
I noticed if i pull Brown wire off from the right Side 14 pin connector behind the control panel the blower motor starts to run and the Red Light stops flashing., but it still wont respond to any button.

Brown is usually ground In these cars but when i multimetered that brown to chassis there was some 15Ohm resistance In between?
There is also yellow/Green wire In that same connector which goes straight to chassis. (zero resistance)

So i got short circuit In that brown wire?
Just cant really see where its coming from.

 

[gsxr]

Wiring diagrams should be in either Group 24 or 83 of the FSM:

Mercedes Benz Model 124 - M119 Maintenance Manuals

At least you are making a little progress!

 

[Sam]

I have done some investigating and testing with no luck so far but now its blowing fuse number 2?? Any ideas?
Is this something completely different issue, have i messed up some wires?

And if i unplug Brown wire from the rightside connector the blower starts to blow slowly and if i also take yellow/Green wire off it starts to blow faster?!

 

[Sam]

Oops sorry it was fuse 1.

Any ideas?

 

[Sam]

I got that fuse issue fixed.
Fixed some radio wire connections made by previous owner...

But still no luck with the heater/ac.
I have soon disassembled the interior to plain metal but everything seems to be ok so far...

 

[Sam]

Does anyone know Ohm values for the parts of the heating system?

Temp sensors, water pump, monovalve etc.
Any way to check blower regulator?

 

[Sam]

Today i changed blower regulator, nothing changed...

Help?!