Heating fan

[CitroJim]

It's likely not been used for several years Davie so likely needed a bit of a kick to properly wake it up...

I ran it for about ten minutes before despatching it...

Hope it now carries on running trouble-free

[daviemck2006]

OK so I haven't been in the activa this week so I don't know if this is working or not at the moment. I have bought a relay and associated fuse, wire and connectors to do a relay mod the next time I have it up the road. The fan I removed from the car should have arrived with Elma today to see if he can fit new brushes into it and resuscitate it. If it gets repaired I may well request it back. I don't really know.

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[daviemck2006]

Elma should have a broken fan by now. I hope he can get it fixed as the one I have is now not working at all. I've tried wiggling the ignition switch, it makes no difference. The power in terminals are showing 14.4 volts constant when the engine is running and does not change whilst wiggling the ignition. So it looks like the fan Jim kindly sent to me is goosed too. At least it is milder now, so not a big need for it, I'm also very rarely in stop start traffic so the through flow of air is just enough at 60 mph, if I need a big defrost it's a bit awkward doing 120 with a frozen windscreen lol

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[CitroJim]

Sorry to hear that Davie

It was honestly fine when I tested it before despatch...

[CitroJim]

Davie, check the brushes

[ekjdm14]

Just a thought, have you had a test lamp on the fan terminals Davie? You might be getting voltage just fine through the switch but without any amperage behind it there won't be any life in the fan. A test lamp would at least try to draw some current and show up a flaky contact better than a meter...

Also, off topic again. It did indeed turn out to be the fan switch on the Escort! It's currently in bits though for a new radiator crossmember as well as an underbonnet refresh/tidy up and a thermostat housing too (old fan switch has welded itself to the original to the point I'm scared of breaking it or the head if I apply any more force!)

Hope you get sorted soon Davie, sounds like you could use the cabby's quickclear heated front screen at times!

[daviemck2006]

I think I have got to the bottom of this. First of all there are signs of the fan having been catching on something. My mate put it in because my hands weren't working that day. Second the brass / copper centre core pictures was absolutely filthy and pitted. Third the contacts were very unevenly worn. I managed to smooth the core and the contacts with emery paper, and when I put it back together but not in its place and started the engine the speed the fan went was unbelievable! It started when asked about 10 times and ran for 15 minutes. I've now put it back in the car and sitting very toasted doing a citrobotics session. I've stopped and started the engine a few times and it is going when asked. Fingers crossed this time.

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[CitroJim]

Excellent Davie It must have been stalled then - hence the commutator damage. You were bloody lucky it didn't overheat and set fire to the car...

The commutator was shiny and bright when it left me. There is no way I'd have sent it if I had the least suspicion of it... I also blew it out clean with an air-line before despatch...

Hope it has not suffered too much...

Fingers crossed it'll keep working now

Just goes to show it's hard to trust anyone to do a decent job... As I said in another thread, if you want a good job doing you have to do it yourself...

[daviemck2006]

I've hardly used the car and only short journeys Jim so I maybe have been lucky. It's been too cold to use a car without effective heating. If it stops again I shall pull the plug off it so it can't burn. I never even considered that that could happen.

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[ekjdm14]

Wow, lucky escape for the car & motor lol... Looking at that commutator brings to mind a question I've often pondered but never really sought an answer to. When a commutator wears, due to it's shape both the surface area and relative "timing" of the segments will gradually change. How does this affect the efficiency/power of the motor? in particular it's ability to self-start...

Just wondering if there's a certain point at which the motor would become weak or intermittent due to timing issues, and how deeply worn a commutator would have to be in order to get that way...

[Stickyfinger]

Why would this not blow the fuse ?

[ekjdm14]

Why would this not blow the fuse ?

I *think* because the armature wouldn't be drawing much more current than usual, but because all said current was permanently directed through just one winding, that winding would eventually overheat and possibly ignite any fluff/lubricant in the vicinity...

That said, I could be wrong on that. Also I'd hope that when the winding got hot enough the insulation would break down and cause it to short out, thus blowing the fuse... But then that may be after the heat has caught something else... I stand open to correction on this, but it's how I think it'd work.

[Stickyfinger]

OK thanks.....is there any way of adding a level of protection ?

[RichardW]

Had similar on a BX - smell of burning, and fan on go slow; had to stop on the hard shoulder of the M6 and unplug it!!

[ekjdm14]

OK thanks.....is there any way of adding a level of protection ?

Only thing i can think is either an easily accessed circuit breaker with a much lower trip amperage (easy access as it would likely trip every time the fan was started on a higher speed, owing to the initial current to start the motor) OR some kind of thermal cutout, although i fear it'd be a bit of a mission to mount it/them somewhere they'd be effective in a stalled motor situation.

I think the best level of protection is just to keep an eye on these sort of things as our cars age, and at the first sign of a fan acting strangely then make sure the relay mod is done and done properly, and drop the motor out for inspection/maintenance. (add to that, knowing which fuse supplies the fan to aid in quick removal if/when your fan ever did stop).

Really though, i don't think there's a huge risk of Xantiae going up in flames en-masse due to this particular issue. From how i read it, the stalled motor was a result of incorrect fitting and is now rectified. Could be one for the future though, as they ain't getting any younger. (like a fine wine though, i think a good Citroen in caring hands gets better with age)