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Hi all,

Have been trawling through the forum to try and find info on an Air Con/coolant blower problem without success. Here's the story:
I have a 1999 2.0 HDI diesel (GLX model - D8 I think). The Air Con didn't work when I bought it but finally got round to having the condenser replaced and system re-gassed. Once this was done a problem showed up. Neither of the fans (twin fan model) come on when the AC is turned on, either on auto or aircon setting. After a few seconds the STOP light stars to flash. I guess the ECU thinks it has no cooling. If the setting is switched to eco (no aircon) then all seems well. If pin 2 on the centre relay is earthed then both fans run at slow speed. If the blue connector, which I believe is the engine coolant sensor is unplugged the the left hand fan (if you are standing in front of the car facing it) runs at full speed when the ignition is turned on. Everything seemed to point to the engine coolant control module (bitron?) not supplying the earth. Went looking for the bitron in the nearside front wing as per every post I've read. Nothing there. Not even a place/plug where it could have been. Went to the local dealer and asked for a price on one (just to see what it looked like). He said according to the VIN number which I gave him my model doesn't have one, nor does it have an air conditioning control unit. More than that he couldn't/wouldn't say.

Come to think of it, as the HDI seems to run so cool, don't even know if the fans ever worked as they are supposed to, regardless of the AC problem. I have rotated the three relays so each is now in a different spot. No change.

Sorry for the long post but I'm tearing my hair out over this (what little hair I have)

Has anyone else had any problems in this area? Any chance of a schematic/circuit diagram (even hand drawn), anything to help point me in the right direction. Haynes says it has an engine coolant control module, so it is obviously no use for this problem.

All suggestions appreciated

Hi there, welcome aboard.

Hmm, too late for a bitron, too early for a pressostat There are those with access to wiring diagrams (I'm not one of them I'm afraid) so hopefully they'll be able to give you a bit more detail on that score. I've been pouring over the parts diagrams and I can't figure out what controls the fans for cooling the air con, my old D8 has a "temperature box", which I suppose is what this bitron is actually called. However on the diagrams for yours it's missing... In the absence of anything more useful to tell you, I reckon you should check out the wiring - it seems to me the wires end somewhere around the battery tray, which is the usual place for weird underbonnet electrical faults

Thanks for the reply.
I was able to trace the wire which is, I think, supposed to carry the missing earth. It goes to a connector near the battery and then disappears into the loom. Mind you, I only have the inaccurate diagram to go by so I might be chasing the wrong wire. There doesn't appear to be any damage, corrosion etc., and there is continuity up to where it disappears.

Ive bever even heard my fans come on but engine never seems to get too hot

Anyone else have any ideas as to how this all works?

Can't believe I'm the only one who has ever had problems in this area.
Any educated (or not) guesses/theories accepted and appreciated..

OK, so here is what I found out:
The sequence is that the engine must run first, then the interior fan must spin next, then the dashboard aircon switch must be on, and lastly, the two cooling fans must start at the low speed.
If it doesn’t get that far, then the fault is in the above sequence, and the system hasn’t got to the pressure switch and compressor yet to find out what state they’re in.
My interior fan was intermittent. I pulled it out and found the single red wire was burnt at the spade connector. Repaired it, put all back in and guess what? Still the same, except the interior fan now works properly.

I found if I disconnect the brown connector pictured (I hope - haven't tried to post an image before), then the stop light no longer flashes. Anyone know what sensor this is?

Would this thread be better off in the electrical forum? Maybe the moderator could move it - might be seen by more people able to help.

You might want to change the title of the thread to something more descriptive; that'll get more people looking at it

womcat wrote:I found if I disconnect the brown connector pictured (I hope - haven't tried to post an image before), then the stop light no longer flashes. Anyone know what sensor this is?

That's something to do with the air con, pressure switch?