Hi-
My heater/air blower runs on 3&4 only. As I understand I should unplug the resistor from the back of the switch and measure the resistance values as the first plan of attack, correct? What should the resistence be? I saw the values on an earlier post for an 83' or 84' but would they be the same? Also if that's not the problem, what should I do next?

Regards,

Tim H.
VT USA

I think the problem is that your fan speed resistor is blown for the lower speeds. You'll need to replace it, which as you probably know is no picnic. Good luck.

Damn! Suggestions for a good source or the usual suspects?

Thanks,

T-

The newest Volvo Service Manual Wiring Diagrams that I have covers the 1988 240. Maybe things didn't change much from that year to your model.

There are three resistors, four wires. The wires run from the fan switch into the blower box, where the resistors are mounted in the air stream for cooling.

Between Black and Brown wires the resistance should be 1.9ohms.
Between Brown and White wires is 0.7 ohms.
Between White and Blue wires is 0.2 ohms.

The red wire is the only one going to the motor. So, between red and black you should have the sum of all the resistors. Etc.

It's a good idea to check the resistance with the wires disconnected from the switch. If your resistors are indeed mounted on the back of the switch and not in the blower box, all the above is possibly inaccurate - sorry.

Good Luck,

Bob

:>)