Heater fan help

[rknowles]

I have 1994 Volvo 480 GT 2 litre
Heater fan has stopped working.
There's power to the switch - but only 7 volts
There's also power to the resistor chain - again only 7 volts.
Car battery is healthy!
Why only 7 volts?
Fan works OK on AC max but on nothing else.
Resistor chain is oK - resistance values are as expected.
Wondered about the VEM but don't know where it is or what it looks like.
Can anyone help?
Does anyone have any other ideas.
Any help would be greatly appreciated as I'm not sure where to go from here
Ron Knowles

[Clan]

you will need to take the VEM out , the control unit with the push buttons on . then dismantle it . there will be some dry solder joints in there , have a close look with a magnifying glass and re solder all the heavy current carrying tracks ..

[rknowles]

Began to tackle this but....
Looks like itcould be difficult to remove the VEM. Do I need to remove most/all the facia to get at it. or can it be eased out?
Ron Knowles

[Clan]

The whole plastic frame around the dash comes off reasonably easily after removing the screws , some hidden behind light switch , info centre switch and blanking panel on top left side etc then more screws for the VEM ...

[B20F]

Here's a howto from the 480europe forum, incl. pics. The most difficult part in removing the VEM is removing AND re-attaching the slider cable. Be carefull not to loose the spring thingy with which the cable is attached to the VEM. And when your at it, replace the small light bulbs from the VEM whilst out! Don't ask me why...
http://www.volvo-480-europe.org/volvo480/faq/index.php
(click on electrical system and then ventilation sometimes doesn't work)
Also in the FAQ there's a howto for removing the dashboard facia. click on body and intrior and then on replacing dashboard lightbulbs.

[rknowles]

Thanks for all the advice. Thought I'd clean and jiggle as many accessible connectors as I could easily get at before tackling the VEM. The damn thing decided to work then. Fingers crossed - but I am keeping all the advice in case the solution is temporary.
Ron Knowles

[B20F]

With almost 100% certainty it's only a temporary fix. Better to repair it now and good before the real wet weather kicks in. Nothing worse than driving with steamed up windows without the defroster working! This failure always starts intermittently and slowly gets worse.

[Chris Wickers]

I have repaired mine years ago, then replaced it with a brand new one, and finally had to repair it again!

Once out, it is fairly straight forward to spot the key duff joints (they normally fracture) but it is worth looking at EVERY one under a magnifying glass!

As previously stated biggest problem is the cable and clip...........

Finally take care of the plastic surround, they are no longer available!

Chris

[rknowles]

You're right - it was a temporary fix - thing has stopped again. I fed a 12V supply direct to the switch and the fan worked fine on all speed settings. I now have the facia off but cannot see how to remove the VEM. There are two brackets -one each side which seem to be fixed solid and VEM cannot move. I have removed the two screws connecting the VEM to these brackets but now it seems I have to bend the brackets outward to free the VEM. Am I missing something? Any help/advice will be welcome.
Ron Knowles

[rknowles]

Went back to tackle heater problem this am. Finally got VEM out and opened it up. Found bad solder joint - resoldered and put everything back into car. It seems to have fixed the problem - permanently I hope. Found the whole job quite awkward - hope I don't have to do it again.
Thanks to everyone for advice.

[GTMaster]

Thought i'd reply after having the same problems. Thanks for sharing the info off the 480 site regarding what point to solder. Something a bit about the removal:
It's best to remove the whole central panel. The instrument panel has to be taken off first (4 screws , removal of connections, lowering of steering wheel). After removing the screws from the central panel, it can pretty much be pulled out nearly all the way. It's best to disconnect the clock, and the small storage box. If you're radio has long enough wires, then it doesn't have to be disconnected (especially if you don't know the security code).
The VEM has a screw on the right hand side as well, but behind the console. Afterthat, the wire connections can be removed. Quite tricky, as they're hard to pull out. But the worst of all are the vacuum tubes. There are two special washer- like safety discs that secure the tubes from falling off. I bet 99% of the time they're broken off, as i broke both. You can always glue them back. The whole heater flap wire can be pulled off.
The whole procedure is only tricky because it's easy to break the plastic. Too much prying shouldn't be involved. If everything is pulled apart, then it'd be a good idea to clean the whole console out, check other wiring and leads, change the light bulbs etc.
After doing it once, it'll go easy the second time round :)