My blue baby has been without a properly functioning blower motor switch for a couple of years now and I'm getting tired of driving around with the windows down and a squeegy on the dash.

A few years back my buddy replaced the original (broken) motor with a used one from a later year (1984? maybe?). I don't quite know what he did, he jerry-rigged something so that it just had one speed with an on-off switch because "the wiring was different". Taking a look behind the panel now it seems he cut most of the wires leading into the original 4-way switch, leaving two wires which he ran to the on-off switch.

The problem is that the motor runs WAY too fast, so there's no heat, tons of noise, and it melts any switch I put on there. I think he must have taken out the resisitor or something. Anyhow, I'm not a mechanic and I kinda dread taking the whole dash apart (and getting under the steering wheel) so I was hoping to insert some sort of variable resistor (plus on-off switch) for it, since I have the two wires already outside the dash (in case of emergency I can connect them for instant defoggery).

Suggestions for how to go about this? Is this feasible? My car is in pretty rough shape and I'm just looking for an easy solution. I live in Vancouver, BC, and I'm not sure where to get parts; I checked The Source (formerly RadioShack) but they didn't have any beefy looking resistors, and my local autoparts place came up empty-handed.

I'm handy with a soldering iron and I've taken university level physics....so I think I could do something here...but I don't know what resistors I'd need. Help?

Also - what manual would you folks recommend for a non-mechanic wanting to learn how to fix this car?

I've succesfully built and installed a circuit with the three resistors and a 4-way switch. I also had to learn what relays are (heh) but it all seems to be working ok.

Circuit diagram: http://www.bookwyrm.ca/hostedimages/blowercircuitdiagram.gif

Here's my completed circuit:

http://www.bookwyrm.ca/hostedimages/blowercircuit.gif

I used 0.22, 0.68, and 1.8 ohm resistors. I added some bracing in there to keep them apart, also added stability for when I installed them in the car so that I could keep them away from other stuff to avoid overheating. Currently they are installed up above where the passenger's feet go, behind the glove box. It might not be the ideal location but there's lots of space all around every resistor so hopefully it will be all right. I'm used to not using the blower AT ALL so I won't be running it too much, I don't think.

Of some help was the installation manual I found at ipd: http://www.ipdusa.com/uploads/sku_files/11010_INST.PDF

Now I just need to figure out why I'm only getting cold air. I don't know if the thermostat is broken or if my radiator just needs flushed out. I'm not overly concerned as this fix was more to deal with fog issues than heat, and having something blowing on the windshield is way better than having nothing blowing on it.

The older blower motor had 4 wires coming off it from different places on the windings giving 3 different speeds determined by where the wires were patched in.

The new motor has just 2 wires coming off it, giving just one speed. As you suspect the speed was reduced with a resistor with 4(?) wires coming off it. So basically you need to include a resistor in the circuit to reduce the speed. The resistor tends to get hot on lower speeds (increased resistance) so must be installed in the air stream.

However, as the other wires are cut off, your idea of using a variable resistor seems to be a good one. You may not be able to find one looking in the 240 Volvo area as they weren't used.

I may have a spare resistor lying around that I can get the resistance readings from so that you know what range the variable resistor needs to have. Will post back.
--
As you are in Canada, Canadian Tire sells the 240 Haynes manual #97020 for about $20, but it covers '76-'93. Your 75 240 probably has a B20 engine, common to the 140 series. So you may need a 140 manual as well.

See
http://www.nuceng.ca/bill/volvo/volvohome.htm
--
1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.

The resistor, Volvo #1259687, has three resistances printed on it. 0.2, 0.7 and 1.57 ohms.

I guess, if you can't find a variable resistor, you could use individual ones of similar resistances wired to the 4 way switch.
--
1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.

Contact IPD in Portland Oregon. Give them a call. They carry motors, switches and resistor blocks for three and four speeds.

WWW.IPDUSA. COM. for the phone number.