Climate fan never stops

[shelterit]

Hiya, first time poster. Got a V70 2002 (which I love) who's fan all of a sudden decided to run at full speed, and never stop. I've yanked the fuse for the fan (slot 26), and at least it won't drain the battery, but summer is approaching and the heat is going to cook us all.

This weekend, after a few months of research, I decided to pull out the climate control panel (because the fan speed button wasn't working, and I thought it was related) to see if something obvious was there and to at least confirm it wasn't dodgy. I popped the fuse back in, and the climate control panel seems to work just fine (and I fixed the button; glued a bit of plastic that had broken off). (I did notice that there's now an SRS airbag error message after putting it together again. Anyone have any clues on that?)

So I suspect it's that thing that interprets whatever signal the CCP is giving, however I'm getting mixed messages as to where it might be and what it looks like (bit it apparently is attached to the fan motor?). Some claim it to be behind the glove compartment, or under it, or under the passenger seat, but I've been in all three spots and can't really see it (although, to be fair, I'm not quite sure what I'm looking for). What does it look like? Does anyone know the part number? Or how much they usually are? And where *exactly* it is located?

I'm a fairly noob when it comes to fix cars, but I'm a decent engineer, I just don't know what I'm looking for. Please help!

[JRL]

Can't help you with your primary problem but you pulled the climate module without disconnecting the battery
Now you're going to have to go to a Volvo dealer to have it cleared (this is the ONLY way)!

[DGM]

Normally when the fan runs full speed the problem is a defective power stage module. It is often called "the resistor module" because fan speeds were controled by resistors in the past. Now these units have been transistorized.

The module is colocated with the fan motor. Do a search on this site, this problem is common.

If you ever decide to change only the module, be aware that a motor drawing too much current can destroy the new module. It is why they are normally changed in pair.

It would be advisable if you replace it with a salvage assembly to "lubricate lightly" the shaft ends of the motor to reduce bushings friction on shaft and improve longevity before reassembly.

Here is a link that will tell you more about it. The motor is located behind the passenger glove box on a left hand drive car.

https://www.matthewsvolvosite.com/forums ... =9&t=40825

It is an easy job to do, excepted for two mounting screws that are hard to reach.

[shelterit]

Now you're going to have to go to a Volvo dealer to have it cleared (this is the ONLY way)!

By "dealer", do you mean any service place that has a computer linkup, or does it have to be specifically a Volvo dealer? (I live a few hours away from where all the fun is, apparently ... ) And is there any explanation (that makes seminal sense) for why this happens? (Apart from them making it hard for people to fix their own cars )

[shelterit]

the problem is a defective power stage module. It is often called "the resistor module" because fan speeds were controled by resistors in the past. Now these units have been transistorized.

Thanks, that also explains why the terminology seems to be all over the shop.

If you ever decide to change only the module, be aware that a motor drawing too much current can destroy the new module.

Does this happen often?

It would be advisable if you replace it with a salvage assembly to "lubricate lightly" the shaft ends of the motor to reduce bushings friction on shaft and improve longevity before reassembly.

Sounds like a good idea, but what does it mean? Get a used motor from a junkyard or similar, install that instead, use for a little while (how long?), then replace it with a new unit? (And by unit I mean motor and power stage module together)

The motor is located behind the passenger glove box on a left hand drive car.

Where would it be in a right-hand drive car? (I'm in Australia)

https://www.matthewsvolvosite.com/forums ... =9&t=40825 It is an easy job to do, excepted for two mounting screws that are hard to reach.

Brilliant, thanks. Not sure why this never appeared in my research, it's by far the better info I've found in a while. Thanks. I'll get back to you all on how things go.

[DGM]

Does this happen often?

This problem is fairly common. I have not done an extensive evaluation of what is happening inside the module but from my understanding the high current drawn by the motor stress the module to the point where it is shorting out.

Sounds like a good idea, but what does it mean? Get a used motor from a junkyard or similar, install that instead, use for a little while (how long?), then replace it with a new unit? (And by unit I mean motor and power stage module together)?

I meant that if you decide to replace the fan assembly with a junkyard "unit" it would be a good idea to lubricate the shaft bushings of the motor before to install.

Ideally you should install a new motor with its power stage module.

Where would it be in a right-hand drive car. I'm in Australia?

I am not familiar with "this side of the road" but I have looked at my documentation. It is located on your passenger side where is your pollen filter. Follow the procedures given in this link to replace it.

https://www.matthewsvolvosite.com/forums ... =9&t=21343

These pictures were taken for a left hand drive car. It is reversed in your application.

Now you should have everything you need to rock & roll.

[shelterit]

Hi all,

Just a follow-up on my original posting.

After much to and fro I got ahold of a second-hand heater electrical engine (well, I asked for the resistor module, got the whole engine, so now I have a spare engine lying around ...) for 200AUD (which, in retrospect, is 100AUD cheaper than the outside mirror I also had to replace). For those with a leftie car I can confirm it is on the passenger side;

- remove the glove box completely, and the panel underneath
- remove the 5 screws to the engine (it's roughly in the middle, you can't really miss it, even though it doesn't look like an engine much at first)
- prepare to wrestle it out. A lot. Like, a hell of a lot. There's very little room for wiggle, and I spent, what, an hour trying to get it out. It's tight, alright.
- replace engine (or just the resistor module)
- prepare to get it back in. A lot. Like, a hell of a lot. Another hour of wiggling and shovelling and grunting, easy.

Plugged all wires back, put the glove box back, sealed everything fine, and the thing worked beautifully on the first go. I'm a happy camper, once again!

A side story is that the plastic "thingy" that connects the fan speed button (so, inside the button) with the climate control unit had broken, so I had to dismantle the unit (first, pull it out, pull out the cables [kind of a mistake], unscrew and open, unscrew and peel another layer, find the button and controller) to super-glue it back on. Worked on the second go. The trick here is that the computer now reports some issue with the airbags, which (as written by a poster above) happens because I pulled the electric cables out of the climate unit unawares. Apart from the computer message, though, it all works fine.

So, diagnosis and suggested application was spot on. I also got the "Volvo S70, C70 and V70 Service and Repair Manual (Haynes Service and Repair Manuals)" which helped a lot, even though the pictures are grayscale and sometimes a bit hard to figure out, for 30AUD sent from the UK.

All in all, I think I spent 500AUD for something that at the repair shop would easily have put an extra zero on that figure. Thanks all!