405 with A/C. no cooling fans

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istme
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405 with A/C. no cooling fans

Post by istme »

NITHER OF THE COOLING FANS ON MY 405 1.9TD OPPERATES. I GATHER ONE FAN(I DON'T NO IF LEFT OR RIGHT) SHOULD BE ON WHILE THE A/C IS ON.
I HAVE TRIED TO OVERRIDE THE RELAYS BY THE FANS AND CAN GET BOTH TO RUN SO THE FAN MOTORS ARE OK.
I HAVE BENCH TESTED ALL THREE RELAYS AND THAY ALL TEST OK.
WHEN REFITTED TO THE CAR THE MIDDLE & RH ONES BOTH ENERGIZE BUT IT SEEMS NOT THE LH ONE. DOES ANY ONE KNOW IF THE WIRING DIAGRAM SHOWN IN THE HAYNES MANUAL (WHICH IS FOR NON AC MODELS) IS STILL APPLICABLE TO AC TYPES. AS A/C TYPES HAVE AN ELECTRONIC CONTROL BOX(ANYBODY KNOW WHERE IT'S LOCATED?) AND NOT A SIMPLE RAD SWITCH FOR THE FANS. I DON'T KNOW WHICH RELAY SHOULD CUT IN WITH THE A/C OR IF THE RELAY IS + OR EARTHED SWITCHED BY THE AC CONTROL UNIT. I HAVE TESTED THE "BITRON" COOLANT SENSOR. IT'S RESISTANCE CHANGES FROM AROUND 1.7K OHM ON A COLD ENGINE TO +5K OHM WHEN HOT. IS THIS NORMAL?
Geo
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Post by Geo »

I have exactly the same problem on my 405 1.9 TD - began last week in France in 31 degree temp. Engine remained cool while on the move but, when stationery, and when the rad fan should kick in to supplement the cooling system, the temperature climbed alarmingly quickly. Some sweaty palm moments at lights, traffic queues etc.
Inoperative A/C fan only added to the misery in the heat, although there did seem to be some (limited) A/C effect coming through the blowers?
My mech knowledge is basic so after checking fuses (all OK) have booked it in to local dealer for check and repair. I'll post the outcome in case it should help. From a trawl of other Pug sites, this does seem a not uncommon problem.
Geo
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Post by Geo »

Aargh! Not yet clear if lack of fans is cause or effect, but news from garage is that head gasket has gone. Approx £400-500 bill expected, more if head needs to be shimmed(?). Given that generally the car is a reliable workhorse that suits its family use perfectly, I'll just have to swallow hard and fork out.
Anything I should be asking to have done while the head is off and the thing is in a generally dismantled state - on the basis that it may be better to anticipate potential future difficulties and head these off with some preventative work now? Cam belt already replaced at 72K service, and new rad about a year back - mileage now at 90K.
Any 'bluffers guide' type of advice for driving out the best deal from the garage?
pat@pug
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Post by pat@pug »

Bought my Peugeot 405 in April with 118k miles on the clock ( first 85k with full Arnold Clark service history ) and love it!
With 55 mpg I'm saving a tenner a week on the Hyundai I had.
I have the same non working fan problem-noticed while pulling a caravan from Lanarksire towards Ayr.
I have a 1995 GLX D saloon with Air Con.
With the engine off but ignition turned on, check that with the Air Con ON the fans run on SLOW ( both ). If not it may may be the ECU ( wherever that is! passenger side inner wing? )
If they run slow, remove the BROWN SENSOR plug from the thermostat housing. The fans should run at full pelt!
If they do, I suspect the sensor on the thermostat housing. If your of an elecrical/electronics bent check that the resistance changes with temperature with this sensor.
If they don't, well..... Bitron sensor? dodgy relay?
Let me know what you find
je@perimeter-alarms.co.uk
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Post by je@perimeter-alarms.co.uk »

I have had the same problem since buying the car (405 1.9 TD) some 4 years ago. At the time of purchase the initial engine had done 136K and was suffering from a head gasket problem and as the car was to be used as a taxi I had the engine replaced with a younger engine that had done only 34K. Since owning this car I have met many experts, the first one,who changed the engine, connected the uncharged and empty air con pump to the reversing lights, which resulted in burning out 2 air con pumps. I then took the car to an AC expert who had done "thousands of these" and later conceded defeat saying "ooh you've got real big problems with this".
I have never had the air conditioning working in the car and it has effectively been disconnected; however the cooling fans problem still exists.
I have found that the cooling fans will operate at a variety of temperatures; but have never failed to work at the higher temperatures ie above 95.
So I have lived with the fault for quite some time and to no detriment( the car has now done 252k and is on the road daily); however 2 weeks ago the fans would not switch off,so removed fuse and then ran in an overide switch. But I was now forced into trying to rectify the "bitron" fault.
Wiring diagram in Haynes manual somewhat confusing but is still correct for the car with air con. The Bitron control unit(a black box about the size of a cigarette packet but flatter and with a multi way plug going to it) is located under the nearside headlight and it looks as though the headlight needs to be removed to get to it. A new one costs £82 + vat Peugeot part number 133830.
I have now changed all three relays and the thermostat housing sensor but the fault remains so it does appear that I will have to change the Bitron Unit as the function of the Bitron unit is to grab control of the operation of the fans regardless of engine temperature and this appears to be what happens.
To Geo I would suggest that he checks to see if there is pressure in the radiator water before he lets a garage loose on a head repair.
If there is no pressure then the head is probably ok; however if the engine has overheated badly because of lack of cooling fans then a head repair may be needed.But you will probably still need to change the Bitron Unit anyway.
Regards JE
john emberton
Justus
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Post by Justus »

I have also experienced a similar problem with my 1994 405GLD. The cooling fans don't appear to come on when I am in a traffic jam. If I was to change to controlling the fans using a radiator mounted switch instead of the Bitron sensor, how would it affect the A/C? Anybody with some information?
Justus
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Post by Justus »

I have also experienced a similar problem with my 1994 405GLD. The cooling fans don't appear to come on when I am in a traffic jam. If I was to change to controlling the fans using a radiator mounted switch instead of the Bitron sensor, how would it affect the A/C? Anybody with some information?
Justus
Posts: 5
Joined: 18 Oct 2002, 13:21
Location:
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Post by Justus »

I have also experienced a similar problem with my 1994 405GLD. The cooling fans don't appear to come on when I am in a traffic jam. If I was to change to controlling the fans using a radiator mounted switch instead of the Bitron sensor, how would it affect the A/C? Anybody with some information?
Justus
Posts: 5
Joined: 18 Oct 2002, 13:21
Location:
My Cars:

Post by Justus »

I have also experienced a similar problem with my 1994 405GLD. The cooling fans don't appear to come on when I am in a traffic jam. If I was to change to controlling the fans using a radiator mounted switch instead of the Bitron sensor, how would it affect the A/C? Anybody with some information?
Justus
Posts: 5
Joined: 18 Oct 2002, 13:21
Location:
My Cars:

Post by Justus »

I have also experienced a similar problem with my 1994 405GLD. The cooling fans don't appear to come on when I am in a traffic jam. If I was to change to controlling the fans using a radiator mounted switch instead of the Bitron sensor, how would it affect the A/C? Anybody with some information?
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