Ford Mondeo III (2000 - 2007) - 03 1.8 Air-con partly works but ....

Honest John Back Room » Technical matters
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Sat 7 Mar 2009 15:15
03 1.8 Air-con partly works but .... - p0l0nium
My 2003 1.8LX has an air-con problem.

The A/C light only comes on (and the A/C works) with the Fan switch set to position 1.
When the fan is set to 2,3 or 4 the light goes out (and the A/C stops working).
The A/C light comes back on again when the fan is reduced to 1 again.

That's a solid set of symptoms ... does anyone know what it means ??

P

Edited by p0l0nium on 07/03/2009 at 15:16

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Sat 7 Mar 2009 18:14
03 1.8 Air-con partly works but .... - injection doc
sounds like its a resistor pack failed. easy & cheap to replace
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Sun 8 Mar 2009 12:20
03 1.8 Air-con partly works but .... - ITman
Hi

I had a funny problem with my air con being on all the time.

Turned out to be the control unit. The bit behing the 3 knobs.

There is a lot of electronics behind there. Costs a wopping £133 to replace. I got a good one from a scrappy, now fine.

Regards

ITman
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Sun 8 Mar 2009 17:02
03 1.8 Air-con partly works but .... - p0l0nium
Thanks folks ... it does point to circuit failure somewhere behind the knobs.

ITman's comment about "on all the time" reminds me that it used to have a habit of switching itself on randomly. I am guessing that something used to be wobbly and has now come adrift .

And I just HATE taking centre consoles apart ... the lugs usually snap and I'll probably leave leverage marks all over the place.

I'll let you know what I find.

P
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Mon 9 Mar 2009 15:28
03 1.8 Air-con partly works but .... - p0l0nium
I found the resistor pack and it does seem to be faulty.

Using an Ohm-meter I can find only two resistors in it
1 is about 1.0 Ohm
2 is about 0.3 Ohm

Funny thing is that resistor 2 seems to be between the wrong pins ... wierd!

Can anyone confirm that there really should be 3 resistors in it like the Haynes manual shows ?

P
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Mon 9 Mar 2009 16:47
03 1.8 Air-con partly works but .... - p0l0nium
THAT's IT !! ... replaced the resistor pack (£12 plus VAT) and Aircon is back to normal.
(Thankyou Mr Injection Doc!)

I assume that the A/C control module detects "Fan on" from a small signal it takes from the top of the lowest resistor in the 3 resistor stack . If the resistor chain is broken then the fan still works but the A/C shuts down on high fan settings.

Its a foolish design: The Resistor pack is not sealed and it sits in the cold damp inlet air, its internal connections corrode open-circuit (the internal connections are wire-wrapped, not soldered cos that would melt!).

In my case the car sat with snow on its front end for two weeks and this is the result.
I can't wait for all the other bits of internal corrosion to manifest themselves :-(
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Tue 31 Mar 2009 10:41
03 1.8 Air-con partly works but .... - Englishbullterrier
Can anyone tell me where the heater blower control resistor is on my 97 Escort 1.8TDi ?

(Only working on position 3)

Many thanks............
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Sat 30 May 2009 19:47
03 1.8 Air-con partly works but .... - macca29091968
Hi, Just joined site to say thanks for your posts as it solved the same issue with my air con as well.

Cheers

Ian
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