Heater fan dosen't work...sometimes!

Post by **kaitsu** » 15 Sep 2004 07:09 pm

the switch most propable. Check also the joint on the cable in engineroom, just before the fan house. That was also very dirty in my case.

kaitsu

Post by **360GL** » 15 Sep 2004 07:22 pm

Did you check the ground of the fan motor?

Post by **Well used 86 340** » 28 Dec 2004 11:00 pm

Hello to those who have contributed all the info on the discussion so far.

My 86 340 has lots of problems but i'm committed to it and although not a mechanic, tend to try what i can before giving in and taking it to a repair shop.

My problem with the heater is just as described earlier. Today I took the heater assembly apart and found the resistor coil. The themal cut out was very corroded but rather than bent it had completely broken away before I had gotten there.

I mentionned I'm not a mechanic, well, I'm not an electrician either. So I took a paperclip and wrapped it around the stub of the thermal cut out and through the coil a couple times.

I put it all back together, started the car and no go on the heater. I double checked the fuses, all good. Am I wrong in thinking the paperclip would conduct electricity well. I don't mind taking it apart again and substituting something else for the paperclip but perhaps someone could help me with the following questions:

Is the paperclip fine and I have some other problem?

Is the paperclip or substitute a very bad idea with a fire in my future.

What would be a good substitute for the paperclip.

Thanks, I'd buy the new resistor pack but I've got no job at present and even less money to spend.

Post by **huskyracer** » 28 Dec 2004 11:09 pm

Hi, The paper clip sounds like a bad idea, can you trace the cut out connectios back to the plug? maybe you could then bridge it out of the circuit, but do use a fuse, the cut out is there for a reason

Post by **foggyjames** » 29 Dec 2004 01:43 am

The paper clip ought to conduct well enough to make it work....but as suggested, it isn't a good idea long-term. The best bet is probably to buy a replacement for the correct part - I seem to recall that it wasn't that expensive last time someone checked.

I still need to get around to fixing this myself, so I've yet to discover if there's a way of bodging it!

cheers

James

Post by **bogbasic** » 29 Dec 2004 02:49 am

Hello, I had the same problem 3-4 of years ago and it was due to the contacts on the cutout device you mentioned being corroded. I think it is a bimetallic strip device that breaks the current supplied to the fan motor if the motor is drawing too much current. Too much current will cause the resistance wire coil to heat up and bend the bimetalic strip so that it breaks the circuit at the contacts. A rub between the contacts with glass paper sorted it for a year or so but then the problem came back and when I opened the heater air intake box, the thing was so badly corroded that one of the metal contacts had broken right off. A replacement unit from a volvo main dealer was around 35 pounds but it completely cured the problem! I think paper clip wire may not have the right resistance so for safety I would get a replacement unit.

Post by **Well used 86 340** » 29 Dec 2004 09:54 am

Hi guys,

Thanks for the advice. I'll have to bit the bullet on this one and hit the dealer for a spare part today. You wouldn't believe how important it it to have a heater in the winter in Finland (ha, ha).

People look at me driving with the windows down in sub-zero weather and surely think I'm crazy.

Thanks again.

I think while I'm there I'll order a manual as well.

Post by **foggyjames** » 30 Dec 2004 03:36 am

I think it's the way forward - you're only looking at the cost of a tank of fuel (from what's been said above). Good luck with it! Let us know how you get on.

cheers

James

Post by **petefarrell360** » 04 Jul 2006 12:11 pm

WARNING - Thread resurrection in progress........

Ok, so knowing about all these problems, yesterday in the crazy heat, the ambient temp gauge was reading about 37 degrees, I decided to turn the fan on just to circulate air before I got in the car. It worked perfectly when the car was jsut started, got in the car, fan off, windows down. About 3 minutes later I arrived where I wanted to be, but had to pull up to collect the post, so left the car running and thought I'd just put the fan on the keep the air circulating while it sat there. Nothing from any three settings, however I do know it wasn't the switch. Tried again just before I switched the car off nothing, then an hour or so later, started up, worked perfectly.

Now, am I right in thinking this must be related to this resistor pack in some way? It could be on it's way out, seen them before, but could it have just been the extreme heat fooling the resistor pack, or more specifically the thermal cut out? Maybe my understanding of it all isn't right, but if the heat was extreme enough then could it have the effect of cutting the power at the thermal cut out thinking it's preventing a fire.

If that's the case then I won't worry, at least it's not the middle of winter, so it's not needed, but it is useful as I say for circulating the air. I've more pressing things to sort before I start taking the heater box apart to check this out!

Cheers,

Pete

Post by **Chris_C** » 04 Jul 2006 01:30 pm

I'd be tempted to say you could be right Pete, although I've never seen one do that, and I'd suspect your pack is on its way out anyway, and thats just an early sign. How do you know it wasn't the switch? Although the only car I know that has had a dodgy switch was Fake, and that was after being sat not moved for 3 years, after lots of wiping backwards and forwards through the settings the switch and relay contacts cleaned up.

Dude, if you are keen, I'm in semi break mode, today I'm working on gauge panel copies, and my rev counter trick, but if you want, I can upgrade proceedings to emergancy heater pack design/creation?

Post by **mac** » 04 Jul 2006 03:22 pm

Ready to be shot down - but I cannot recall ever having come across a failed fan switch.

Could well be resistor pack - known to be troublesome etc.

But - from your description it sounds very much like the thermal cut out (aka 'otter' switch - named after the main manufacturer) doing what it's designed to do (but probably at a lower temp. than it should). Underbonnet temps. get pretty high anyway - but with high ambient, a bit of heat soak, period of idle with low/no engine fan speed, -- soon get that little cut out hot n' bothered.

My advice is don't loose any sleep, if the resistor pack is on the way out it's gonna fail anyway (can't do owt about it) so let it do it's own thing but keep your eye out for a replacement. (sorry Vart had my last one.)

Mac.

Post by **petefarrell360** » 04 Jul 2006 04:51 pm

Right, Chris, don't panic then mate, carry on with your specialist work!! Cheers Mac and Chris, I can confirm 100% that the switch is working, as there has always been a momentary loss of sound from the sub if you switch the fan on or off, one of the two, I forget which (in both my cars actually), and it still did that when the fan wasn't working.

Today, the fan was fine, all day, until exactly the same spot as it happened yeasterday! Being there prompted me to try it, and it didn't work. Switched the car off, turned it back on, good as new. Now would that have any reset effect at all? Or maybe it had just cooled down a tad. But yeah, if the ambient temperature is 35 + degrees and the engine bay does indeed get very warm, I think that is the case.

Cheers Guys,

Pete

Post by **mac** » 04 Jul 2006 06:46 pm

No reset effect - purely affected by temperature. If it's cutting early underbonnet temp.may be borderline in this weather. See what it does when its cooler later this week.

Mac.

Post by **foggyjames** » 04 Jul 2006 08:19 pm

I have a brand new replacement resistor/cutoff pack awaiting measurement by Chris.

cheers

James

Post by **Chris_C** » 04 Jul 2006 08:30 pm

Dude, send that and the injection board down, I have time (but no funding... so any copies of the inj board will need funding up front) and I can get them done this or next week.

Pete, I reckon its the under bonnet temp, as Mac says. If the thermal is rusty and old anyway, then a bad contact will be being made anyway.

Mac, my switch only went as the car had been left standing, it happened to my fan, hazard switch (resulting in no indicators at all till I sussed what was going on as the way its wired) and the main light switch all did it. Shows how good Volvo switches are, 20 or so flicks on each (no opening or contact cleaner) and they all cleaned up, not many switches will do that.

Heater fan dosen't work...sometimes!

Just read the discussion

Thanks