260 E W124 aircon refuses to work

[cjkuhn]

hi guys.

so before i get to the problem a few things to mention
when i got the car the nut on the low side of the pipes that leads to the inside was loose.
the compressor was seized
the condenser had a leak

so the problem this aircon refuses to work even though the compressor has been reconditioned the pipes has been replaced and all the seals the condenser has been replaced all the temp sensors has been replaced the klima ecu has been replaced the dual valve has been replaced the climate control unit has been replaced and still this aircon refuses to work.

if i remove the klima ecu and jump connectors 5 & 7 the system works

i've tested all the wiring but nothing i just can't this thing to work

anyone got any suggestions?

 

[lexman8]

Does the climate ECU have to be reset or coded as it would be on later Mercs?

 

[bolide]

AFAIK, all the Klima relay does is shut off the compressor when it gets a signal from the kick down switch

Does the system run if you bypass the Klima alone? Are 5 & 7 the pins on the Klima?

If it runs with the Klima bypassed, look at the kickdown switch to make sure it's opening / closing

These systems are incredibly simple and there's nothing remotely resembling an ECU in there. Basically the compressor kicks in when the system is switched on, and the compressor drops out when the high-pressure switch tells it to. Pressure then drops & the cycle starts again. The only other thing is a low-pressure switch that shuts down the system when the system is low on gas

AFAIK, in the control circuit all there is is a compressor, magnetic clutch, high & low pressure switches and an on/off switch. There's probably a thermostat in there somewhere as well…

Nick Froome

 

[cjkuhn]

thanks for the replies.

i forgot to mention the cars year is 1988

yeah the system runs when i bypass the klima pins 5 & 7.

i know it's not the low pressure valve because that has been replaced and even bypassing it doesn't make the system work as it would normally.

you seem to have forgotten the rpm sensor on the compressor.

anyone ever tried modding the system so that it bypasses all the small sensors in the dash, roof and outside near the blower to a point where it basically doesn't use the klima?

where would the high pressure switch be located?