Volvo 440 Sxi heater fan problem

Tof · Post by **Tof** » 09 Dec 2010, 13:50

I have a 1993 Volvo 440 ZXi
During the last few months, occasionally the blower would work when in the 'heater' mode, and this now has definitely stopped working whichever fan speed is selected, but the blower still works fine in the AC mode. I have checked out the fan switch on the dash panel, and checked the one relay clipped to the fan resistor bracket (the only relay in that region) and checked out the fan speed resistor block.
Apart from the 11-relay block on the engine firewall, close to the indicator lights flasher relay there are two more relays buried under the fascia on the right-hand side,
Are either or both of the two last-mentioned relays involved, or am I missing something obvious? This problem has got me guessing, that's for sure, so I would appreciate any help.

Post by **billofdurham** » 09 Dec 2010, 15:38

Welcome to Matthew's Volvo Site.

This is a fairly common fault on the 4 series and is usually a break in the printed circuit board.

Switching the AC on activates a relay which bypasses the fan switch so you will always have the fan in AC mode. At this point I could blind you with science but I shall leave that to someone else.

This may help you.. Scroll down to the last post by viggy.

The other relays are not connected to the heater.

Bill.