360 heater fan not running

[foggyjames]

Hey folks,

before i multimeter it on monday, any thoughts on this....

Car misted up, put fan on full power, runs for 5 seconds, stops. Doesnt go on any setting, fuses good, relay(?) clicks when engaging / disengaging top setting, but no fan.

Im guessing its a shot motor, but does anything jump off the page at you?

cheers

james

ps: sorry if you get this twice, but it swallowed the first one...!

[foggyjames]

Ooops....just noticed all the other posts on this.....wasting bandwidth...who?....me?!

Still - those symptoms are a bit strange (running for a bit then cutting out...any thoughts?

cheers

James

[Peter Milnes]

You could have a loose connection which makes contact when no current flows through it and heats up with current which causes it to go open circuit. It could be to do with the resistor pack or the switch or even the motor having sticking brushes.

All the best, Peter

[foggyjames]

Hi Peter!

Sorry if it wasnt clear - It doesnt run at all now. It was when it failed that it ran for a couple of seconds, then cut out. I think a dead motor is favourite, but will find out tommorow!

cheers

James

James - I reckon it will still be dodgy resistor pack in heater unit box on its last legs (intermittent failure is symptom of final death I suspect - which sounds like it came quickly), my view is that fan motors have long life but test with meter or 12v supply across motor which is easy enough. Sounds like you saw my previous posting on this recently.
Dan

[foggyjames]

Went to the car today....fan works perfectly...?!

Could it be the very cold weather causing a problem with it? Its much warmer today. I guess something is on the way out. I was hoping it was the motor, but on looking at my car (with PAS) the fluid reservior is right in the way, so maybe the resistor pack is a more desirable failure after all!

Not much I can do to test it when its all working :) What will happen to the resistor pack if it dies - burned out resistors, or something else?

cheers

James

[Cypher007]

where is the resistor pack mentioned above, as my dad's 340 has the same prob. he's replaced the switch, has power from switch, no power at motor end, motor runs fine when conected directly to battery.

[foggyjames]

Was about to post the same thing!

As well as where is it, how do I get to it? Radio, then heater panel out, or something else

cheers folk!

James

Folks, no, no! not complicated panel removal job - see my earlier detailed posting which I have reproduced below for info (plus other postings on this subject). Replacing the resistor unit is relatively easy - the hard part is shelling out the 43 quid for the volvo only replacment resistor unit part

If your switch makes a 'click' noise when switiching from setting '2' to '3' chances are the switch is OK so can be left alone!
Dan


Haynes wiring diagram basically shows that heater control switch switches current through a series of resistors (in a resistor pack) to control the speed of your heater fan, on setting 3 a relay kicks in to bypass all the resistors (this is the 'click' you hear when switching from 2 up to 3 - if you keep hearing the click your relay is OK I would think) resulting in max fan speed, on setting two there is more resistance, on setting 1 yet more etc to slow down fan.

The most likely thing (and it is quite common apparently) is for the resistor pack to give up the ghost, this is probably what is causing your problem. A new resistor pack is quite expensive from Volvo (40 quid + I think, try ringing them - I think it is a Volvo only part unfortunatly but I would be pleased to stand corrected - other suggestions welcome!), my freindly independant volvo mechanic fitted a new one for me for 5 quid labour and as I was busy that week and as the fititng was so small compared to part cost I did not DIY it.

Essentially the resistor pack is somewhere in the black plastic heater unit box on the bulkhead, access by unclipping the clips that hold the two halves of this box together. Mechanic I use said you can rewire it to bypass the resistors then you can get fan on speed '3' and '0' at least (which may be cheaper if you have a soldering iron and don't mind reduced fan speed choice!), or you could try a resistor unit from a scrap yard. I took the view that I wanted it working on all speed and a scrap one might just pack up again soon.

If this is not causing your problem, or if you have already changed this, the other thing could be the fan motor has packed up (more unlikely to be honest). Fan motor is attached to said black box in obvious position, you could perhaps test this by disconnecting the wires and using a meter, if you have one, or by disconnecting the wires, putting a 12 volt supply across it and seeing if it works or not (hence bypassing all switiches, relays and resistor packs) to see if this is where your fault lies. I think there are other contribs on here about cleaning fan motor brushes etc to improve faulty motors.

Re your point about it kicking in from time to time, mine failed occasionally about 12 months before it finally went and I (wrongly) put this down to faulty dash switch, since it worked fine for the last 12 months prior to finally packing in I did nothing about it at the time!

[foggyjames]

Thanks for a great post! Sounds like the resistor pack is on the way out....will get a 'new' one from the scrappers and analyse what it is / if I could 'remanufacture a new one. I'm guessing its just a board with some power resistors on - in which case £40 might not be so harsh - dependant on the currents involved said resistors might be non-too cheap!

However....thought has just struck me....if 'full power' is a 'straight-through' setting (albeit probably via that same board), it probably isnt a resistor failure....maybe just corrosion on the board terminals, or similar? Will take my one out some time and take a peek.

cheers

James