Mk4 mondeo fan refusing to turn, preventing AC working

[flake]

 

Hi all,

 

New mk4 mondeo 2.3 petrol estate owner here (“Ooooo rare model!”). Please can you help me?

 

The car’s aircon was not great when we bought it, so I had it regassed. Since then, it works great when driving at speed (as low as 8 degrees, confirmed by a temperature probe in the vents.

However, the AC does not work when in traffic or parked. 

 

The cause appears to be a fault causing the radiator fan not to turn, which is preventing the AC working at low or nil speed. You press AC and the fan ignores you (but AC compressor does turn). What’s weird is the radiator fan clearly has nothing physically wrong and briefly turns soon after the car starts.

 

What I have tried so far to diagnose cause:

1. Assuming the first regas was somehow done wrong, confirmed with two separate garages the amount of refrigerant in the car is right and there appear to be no leaks.
2. Changed the AC pressure sensor between regas 2 and 3 with a brand new pattern part.
3. Mechanic scanned the car with a Autel MS908, found a ‘Fan 1 control circuit’ code recorded. He cleared it, instructed the fan to turn and it did. Then the AC began blowing very cold, then the fan stopped. He rescanned and the code has reappeared.
4. Mechanic confirmed that two engine temperature sensors appeared to work, with both reporting the same data to his scan tool.
5. Changed fan control unit for an identical genuine one from a breaker. Went back to mechanic to reset code. Reappeared.
6. Inspected purple control wire from fan control unit, all the way to about 1 inch from the PCM/ECU. This included The 2 tight turns the wire makes, which I read online are a common place you will find damage to the wire. The wire looks like new all along this length, not even a hint of damage.
7. Removed glove box, changed pollen filter. Reseated all connectors I could find under there (hoping one is the evaporator sensor one forum post mentioned as a possible cause).
8. I should mention too that my speedo works, so I assume the car knows when it is stationary/slow. The coolant temperature on the dash also works - indicated as cold when first starting, turns to the middle in a few minutes and never goes past this (even in really hot weather or traffic). I have also directly connected the battery to the fan and is spins nice and fast with no nasty noises.

 

I am considering the following next steps, feel free to suggest alternatives:

A. Assume both the original and used control unit I brought have an issue, so replace with new.

B. Assume the fan motor is somehow triggering the issue, perhaps causing voltage spikes? Replace with new.

C. Assume the PCM/ECU has a fault. Have a Ford dealer carry out diagnosis.

 

I’m really sick of this now and would be very grateful for any advice. Even just some moral support would be nice!

 

[TrevorB]

That sounds odd that ac works at speed.

It could be a poor connection as you suggest the cooling fan does not always work. If the fan does not work the air con won't.

A cheap check/investigation is to check out a very popular fault on the Mondeo which is corrosion/break of the "purple" wire that runs from fan along chassis leg to EMC unit.

There is loads of info about this wire failure on the internet - Type this into google- talkford mk4 mondeo purple wire

Or you could look through this menu and pick out the relevant threads https://talkford.com/community/forum/102-air-con-heating-mk4-mondeo/

[flake]

2 hours ago, TrevorB said:

That sounds odd that ac works at speed.

It could be a poor connection as you suggest the cooling fan does not always work. If the fan does not work the air con won't.

A cheap check/investigation is to check out a very popular fault on the Mondeo which is corrosion/break of the "purple" wire that runs from fan along chassis leg to EMC unit.

There is loads of info about this wire failure on the internet - Type this into google- talkford mk4 mondeo purple wire

Or you could look through this menu and pick out the relevant threads https://talkford.com/community/forum/102-air-con-heating-mk4-mondeo/

Thanks for the reply. See point 6 in my original post. 😀

I finally got my hands on forscan yesterday, reset the code and it didn’t return. Went for a drive somewhere, restarted the car a few times during this, still fine. Fan was still turning when I parked. Didn’t check for code again, danced a jig,

Garaged the car overnight because I had not gotten around to wrapping up the loom with tape yet, so it stayed dry. Just went to start the car with AC on today and guess what.... code is back for the fan circuit (P0480) and fan is not turning again. When i reset it, it returns soon after. ARGH!!!

More and more I am thinking it has to be a break in the purple the wire, but either it’s right next to the PCM where I can’t see it, or somehow it’s in the bit I can see but showing no outward signs of an issue. The thing is, others who had this issue always seemed to see obvious damage in the bits where the wire bends near the chassis leg, when they have shared photos.

Fun and games.

[flake]

2 hours ago, TrevorB said:

That sounds odd that ac works at speed.

It could be a poor connection as you suggest the cooling fan does not always work. If the fan does not work the air con won't.

A cheap check/investigation is to check out a very popular fault on the Mondeo which is corrosion/break of the "purple" wire that runs from fan along chassis leg to EMC unit.

There is loads of info about this wire failure on the internet - Type this into google- talkford mk4 mondeo purple wire

Or you could look through this menu and pick out the relevant threads https://talkford.com/community/forum/102-air-con-heating-mk4-mondeo/

Thanks for the reply. See point 6 in my original post. 😀

I finally got my hands on forscan yesterday, reset the code and it didn’t return. Went for a drive somewhere, restarted the car a few times during this, still fine. Fan was still turning when I parked. Didn’t check for code again, danced a jig,

Garaged the car overnight because I had not gotten around to wrapping up the loom with tape yet, so it stayed dry. Just went to start the car with AC on today and guess what.... code is back for the fan circuit (P0480) and fan is not turning again. When i reset it, it returns soon after. ARGH!!!

More and more I am thinking it has to be a break in the purple the wire, but either it’s right next to the PCM where I can’t see it, or somehow it’s in the bit I can see but showing no outward signs of an issue. The thing is, others who had this issue always seemed to see obvious damage in the bits where the wire bends near the chassis leg, when they have shared photos.

I just happened across this video where the guy had the same code on a transit and it turned out to be dust/gunk in the fan motor. A blow of compressed air sorted it. Seems a long shot, but will investigate the same on mine: 

 

Fun and games.

[TrevorB]

Hi Flake,

My sincere apologies on missing your point number 6 - bit stressed this week, ha ha

Video was a good find, very helpful - hope all goes ok

[flake]

20 hours ago, TrevorB said:

Hi Flake,

My sincere apologies on missing your point number 6 - bit stressed this week, ha ha

Video was a good find, very helpful - hope all goes ok

No worries mate.

I just finished with putting the car back together having sprayed the fan motor out with plenty of air from a spray duster aerosol can. Reset the code, but it promptly returned. Bugger.

[nicam49]

Could it be your 2nd hand fan module has the same fault.. 🤔                            You can't check the integrity of the purple wire by just looking it; you must either meter it out or make a temporary  substitute.                                Good luck and let us know how you get on! 👍

[flake]

2 hours ago, nicam49 said:

Could it be your 2nd hand fan module has the same fault.. 🤔                            You can't check the integrity of the purple wire by just looking it; you must either meter it out or make a temporary  substitute.                                Good luck and let us know how you get on! 👍

I had the same thought today about the control module. Got hold of a brand new fan including new control module. Will plug it in tomorrow and if it works, I will know that was the cause. If it doesn't, I'll be taking another hard look at the purple wire....and refunding the new fan! 

Found an excellent post today which may help a lot with diagnosis, in particular the bit where it talks about the Forscan oscilloscope, since i have forscan now: https://www.fordownersclub.com/forums/topic/94666-ford-s-max-galaxy-radiator-cooling-fan-not-working/

Will report back tomorrow ......hopefully having beat this little gremlin at last!

[iantt]

The purple wire can and does break internally inside the purple plastic outer covering. I would have bared either ends of wire, done resistance check on wire while wiggling harness. Or just run another piece of cable from one end to the other temp. 

[nicam49]

That link you found is  brilliant, 

https://www.fordownersclub.com/forums/topic/94666-ford-s-max-galaxy-radiator-cooling-fan-not-working/

 

[flake]

SUCCESS!

Fitted a new fan and controller from the local ECP, who astoundingly had one in stock for my rare car, and it all works perfectly.

i also tested the new fan with both the old controllers and it all worked, so the fan motor was the root issue (see the video I posted earlier where the same was true, it’s just that in my case spraying it out with air didn’t sort it....I needed a new one).

I have put everything back together including plenty of insulation tape around the loom I had inspected. My wife is especially happy to have aircon in the current hot weather. Feels fantastic to have beaten this gremlin!

My Advice for others is: if your aircon is working fine when driving at speed but not at low speed (or parked), the likely culprit is the Radiator cooling fan motor. This is especially true if the fan turns briefly when you turn the car on, then refuses to come on again. I suspect the car was detecting resistance (or not getting the fan speed desired), then shutting down the fan in case continuing its operation might cause a fire. This would be further confirmed if a scan of the car with a workshop grade scanner reveals a P0480 code (cheap scanners won’t see the code). Hopefully this saves someone else a lot of the annoyance i have had!