405 fans don't work

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rodisi
Posts: 8
Joined: 17 Jul 2003, 23:14

405 fans don't work

Post by rodisi » 20 Jul 2003, 00:44

'94 405 GLX TD w/ A/C - bought in March and didn't realise it until the hot weather that the fans don't work. I've seen postings on this subject from a year ago but no solutions. The Haynes manual is no use as the electrical circuits don't show the Bitron unit. A couple of questions
1) which of the two sensors on the front of the thermostat is for the fans?
2) is the Bitron unit on the near side wheel arch and does it have five 30 amp fuses (I found that one of them keeps blowing)
3) how do I get to the fans (the easiest way)
Thanks for any help.
Ian

wheeler
Posts: 3767
Joined: 21 Sep 2002, 19:07
x 78

Post by wheeler » 21 Jul 2003, 21:05

the 2 pin brown sensor is the one that controlls the fans,not familiar with the 405 but on the Xantia it is underneath the left hand side headlamp,they dont have fuses in them,its just a small black box a bit bigger than a cigarete packet with a 15 pin black conector on it.have you checked that one of the fans aint siezed ? can you turn them both freely by hand ? possibly the cause of the blowing fuse.you have to find out what that fuse is for.

rodisi
Posts: 8
Joined: 17 Jul 2003, 23:14

Post by rodisi » 23 Jul 2003, 00:30

Thanks again Wheeler.
The fans turn freely but I suppose it could be that one of them is burned and therefore present a short to the fuse. What the purpose of the fuse is, I have no idea. I've looked in the Haynes manual and the electrical circuit ignores the Bitronic sensor altogether. Next step will be to try to get to the fans and start following the wiring backwards.

wheeler
Posts: 3767
Joined: 21 Sep 2002, 19:07
x 78

Post by wheeler » 23 Jul 2003, 02:11

disconnect the fans an see if the fuse still blows,this will rule out the fans causing the short.

Dave Burns
Posts: 1916
Joined: 14 May 2001, 05:30
x 2

Post by Dave Burns » 23 Jul 2003, 04:04

If the setup is similar to the xabtia, pulling the wiring connector from the brown bitron sensor should switch the fans on with one running at full chat.
If that works you may need a new sensor but go over the connectors concerned with the system first and give them a scrape, they can get oxidised but still look OK.
Dave

CANDO
Posts: 44
Joined: 27 Jul 2003, 16:18

Post by CANDO » 27 Jul 2003, 22:34

The fuses on the near side wheel arch Are associated with A/C fans. But I don’t know what each one protects. I had a non-working system although I didn’t have a continually blowing fuse. But the system still didn’t work even with a new fuse.
There are three fan relays, which are located in front of the fans. You remove the grill to get access to them. Small plastic bags cover them for protection from the weather.
Here lay the cause of my problem. Two of the bags had split allowing water in. This appears to have caused the short that had blown the fuse.
Worse still the relay contacts were badly corroded. I had to break one relay to remove it! After fitting a replacement (£10 from pug, £1 from a breakers) and cleaning the other relay contacts the A/C has worked ok.

rodisi
Posts: 8
Joined: 17 Jul 2003, 23:14

Post by rodisi » 04 Aug 2003, 15:00

Thanks all for the replies. After reading the manual carefully I managed to get the grill off and got to the relays. Isn't it amazing that some engineer thought "Let's put some plastic bags over the relays - that should stop the water from getting in." Anyway, the relay on the right (facing the car) and corresponding to the left relay in the Haynes manual had two corroded and broken wires. I replaced the connector and Robert is your uncle. Tested yesterday in traffic jam in Hyde Park in 27 degree heat.

CANDO
Posts: 44
Joined: 27 Jul 2003, 16:18

Post by CANDO » 05 Aug 2003, 20:46

Pleased the info was of help.
The plastic bag idea must surely have been an after thought?
Anyway, in this heat, if your system is working who cares!
Indecently I re-protected my relays using cling film and it’s proved
Very effective.