W124 aircon problems

[GSBellew]

The Aircon in my 1994 W124 estate has started playing up this weekend.

On Saturday morning all was fine, everything was working as normal, then on Saturday afternoon I noticed that none of the red lights on the switches were turning on (de-humidify EC and re-circulate). No matter what I do the lights stay off and the re-circulate function will not switch on.

I went looking for a fuse, none in the fusebox or relay box, but then my aircon is a diavia retrofit system, so I guess they could be anywhere? I did find a 25 amp fuse and 5 pin relay over by the passenger side shock tower, fuse is ok but the contacts on the holder look rusty, could this fuse holder be to do with the aircon and could the rusty contacts be causing the problems I'm having?

There are 2 electric fans in front of the radiator fans, as far as I can tell these are not coming on at all.

Does anyone have any idea where I should start looking for problems or for fault finding on the system?

 

[LastMinute]

Definitely check fuses first. ISTR there were two or three inline fuses on the Diavia aftermarket air conditioning on my 1990 230E, as well as several relays dotted around. Look for a power feed coming directly from the battery positive terminal, and check the fuse in that.

My condenser fan came on once in four years, I think, so I wouldn't worry about yours just yet...

 

[GSBellew]

Thanks, I'll have a look for inline fuses in the morning, I've seen a few black connectors under the bonnet that look like they might be inline fuses, so I'll have a look at them, if not I'll trace back from the battery and see what I can find, thanks

 

[Number_Cruncher]

On the diavia system on my 95 E300D, the relay and fuse on the passenger side shock tower is for the fans in front of the condensor.

One of the fan motors on mine had siezed up, and that's what caused the fuse to blow. It's probably worth the 20 seconds it takes to check that both of these fans do spin freely.

I *think* that there are some heater & AC electronics behind the front passenger side footrest.

 

[GSBellew]

Had a look around for fuses, didnt find anymore in the engine bay so I went from the switches in the dash and traced the wires, found a fuse in line with the control box which I found below the dash on the drivers side, it was blown, swapped for a new one and all is working again

Not sure why the fuse went, if it goes again I will investigate it, but for the minute I'll just be happy that its all good again