Mysterious (electrical) air con fault

[nic]

Our doughty bongo made it all the way across France and back over the past couple of weeks but the air-con is just not working at all which made it a real endurance test for us inside.

The problem seems to be that the air-con switch lights up nicely but that nothing happens at the end of the wire that attaches to the air-con unit itself. I have just tested this with a multi-meter and that end of the circuit seems pretty dead.

I would like to trace the fault back but I am not sure where the circuit goes in between the switch (working) and the endpoint (not working). Does anybody know what else this circuit goes through so I can track it back and find where it is failing.

(Just to eliminate questions, the ventilation fans are working front and back at all speeds although only after the front fan motor was taken out and re-lubricated a month back - and a bit of re-soldering applied to the fan resistor unit. The air-con has never worked but I only just got around to replacing the old very dead compressor.)

[missfixit70]

Is it the digital climate control or the manual air con? Your man for wiring diagrams is G8DHE.

[nic]

Is it the digital climate control or the manual air con? Your man for wiring diagrams is G8DHE.

Its the manual air con rather than climate control.

Nic

[g8dhe]

OK, only just got back in from a day of Bongoing so I'll just have tea and then I'll dig the diagrams out for a diesel Manual A/C. If nothing is coming on however its quite likely to be the refrigerant level as it has a sensor that shuts it all off if I remember correctly - I'll try to confirm that later.

[g8dhe]

OK these are for the 1995-1997 WL-T version, the later versions are no different - Click the thumbnails for fullsize images;


The manual version doesn't appear to have the feedback from from the compressor that the electronic version has that senses the refrigerant level. The 10 Amp fuse is number 16 (Right end middle row).

I've not included the ECU pages as its only shown as a block with no contents - but shout if you want it.

Hope this helps.

[dandywarhol]

Try shorting the wires on the condensor located in front of the a/c radiator on the nearside - that should give a current flow to the compressor and that'll tell you that the pressure is too low.

[nic]

Try shorting the wires on the condensor located in front of the a/c radiator on the nearside - that should give a current flow to the compressor and that'll tell you that the pressure is too low.

I'll give that a try this weekend - I figure it will either identify the cause or eliminate on possibility so I can look at something else.

Cheers,
Nic

[ginger colin]

Hi.. I have a 2.0 litre. Same problem, Cheers for the heads up on shorting the condenser. I pulled the 10 amp fuse and it looked a bit tired. The condenser plug was a real struggle to get off. The tab is a squeeze type on the plug and pull it as straight as possible. 20 minutes later a bit of wd40 and no damage I used the old fuse and shorted accross the plug. Hey presto "click" for the pump and "purr" for the fan. Make sure you are selected cab fan on and A/C on.

Cheers.... A recharge needed.

I dont suppose you know the oil type and the weight required.

When i get air con done I always have a full discharge and new oil. The cans from Halfords etc... could be the wrong lubricant type and it is easy to over fill the system. On my mondeo an overfill caused juddering , loss of steering and nearly wrecked the belts... If they hadn't slipped its a big repair... Apparently mercedes use very heavy belts on air con... over filling will cause the engine to stall and at worse wreck the cam belt.... $$$$

[Simon Jones]

There's a factsheet in the members area, but a decent aircon specialist will have the Bongo on their database. They will also drain the system and pressure test it before refilling.

[ginger colin]

Hi.. looks like I have a leak.. the pressure is dropping off over a couple of weeks..

Without ripping everything out, is there a pipe that seems to "go first"....

[rita]

Hi.. looks like I have a leak.. the pressure is dropping off over a couple of weeks..

Without ripping everything out, is there a pipe that seems to "go first"....

Check the pipes and O ring seals at the rear heater box (underneath).You may need to have it pressurised/tested to find any leaks if it is empty.