New member needs help 850 blower motor not working !!!

[vauxhallmaniac]

Hi all i'm new to the forum and am hoping for some pointers on an 850 blower motor !!! the car is a 1996 (850) the blower fault started intermittently sometimes running 3 months without fault !!.... now when i really need it with the cold weather its packed up completely .
My checks so far are power to the blower motor engine running 9v ( should i be seeing 12+v ?? ) removed and ran the blower fan from a slave battery spins up fine....found the climate diagnostic method online and pulled trouble codes 325,411,414,418,419.... here's where i'm stumped..would the drivers side sensor fan seized (414) stop the blower fan running as a safety cutout?? passenger side fan (411) seized or over current... it spins freely and runs fine off the slave battery at 12v ?...also if i slide the fan speed slider should i be seeing the 9v supply to the motor dropping and rising with the slider ? would really appreciate some help from forum members as its off the road with the bad weather till i can get her fixed......Many Thanks Simon

[Cookeh]

That's quite a few codes, even for the troublesome ECC system. The very first thing I'd do is reset the lot and then see which ones return.

[850Red]

Does it have ECC? If so, the slider sends a square wave signal to the power stage, which then in turn sends a voltage to the blower fan (up to 12v full speed). There are many points of failure. Check the fuses, then resistor pack in the blower housing, then the power stage, then the slider.

The other faults you mentioned are unrelated. The blower should always work regardless.

Good luck.

[vauxhallmaniac]

Thanks for the replies guys !!! ........its the 9volts thats throwing me as i would have thought the motor would at least turn under its own steam !! i'll have another look tomorrow can you tell me where the power stage is and is this a relay??? not heard of one before not sure if its classed as ECC my control panel is the same as this eBay item number: 274029344413 Cheers for the pointers i will clear the fault codes and run some tests

[850Red]

Yes, can confirm you have ECC (Electronic Climate Control). The power stage is not a relay, it's digital, wont show on a multimeter, you'll need an oscilloscope. Unfortunately without seeing it I'm not gonna be much use as I am ****e at explaining things.

Where are you getting 9v from? The motor spins at 12v. The +ve terminal is permanently hot, you can run the motor by grounding the blue wire.

[ASt85]

The most likely problem is the final stage power transistor/resistor pack located on the base of the blower, replacements are available.

Try The "how to" here NBthe ephotos are missing, but it is fairly straight forward
https://www.volvoforums.org.uk/showthread.php?t=74907

here
https://www.volvoforums.org.uk/showthread.php?t=82007

and here
https://www.volvoforums.org.uk/showthread.php?t=6632

There are similar issues found in the V70's both P1 and P2 - cheapest and easiest way is to swap it for a good blower from a breaker.

[Graham h hodge]

There's a fuse under the dashboard somewhere near the fan you can replace it for about £100-00 but I souldered a new fuse in ,probably from RS for a couple of £s a while ago (forget these things sometimes)