The car is a '99 Volvo V70 XC AWD. The blower for the heater wasn’t working this morning. When I left work it was blowing a little but not as high as it should on full. Any ideas?
It is either your actual blower motor having difficulty rotating OR and more commonly, your Resistor assy is acting up… I say “acting up” because the resitor assy in newer vehicles is FAR more complex than they used to be “back in the day” when we simply had Lo, Med and High as selections for Blower motor speed. So my theory about your resistor can change rather quickly depending upon how complex VUVU decided to make the blower motor speeds…DOes this have an INFINITE blower speed adjustment? OR the old Speed 1, 2, 3, and 4? Your answer affects the solution so let me know.
As an Example…just this weekend I had to repair an issue on a 99 Jeep Grand Cherokee…Guy said he is freezing in his car because the blower motor will not run…he feels heat but no “forced air” Sure enough it was his blower motor speed controller/resistor assy. His was an infinity type of adjustment so that controller was electronically complex…I went to the junkyard to grab a few resistors…and got them out of the simpler Jeeps…and that resistor pack was NOTHING like the one he had… The low budget one has set speeds…the upgrade has infinite adjustment…
LONG story LONG (what else is new with me) The connections to the speed controller were VERY heat distorted…had to clean them up… However while I was prepping to fix this issue…not knowing what it was b4 hand…I got meself a resistor assy, a blower motor and a blower motor switch… I got the blower motor itself…because i didn’t know his blowers condition…You usually cannot oil the motors so they commonly wear out… If you can pull your blower motor see if its hard to turn by hand…if so TRY to lube it…USUALLY you can access the blower in the passenger footwell area…sometimes its Easy…some not… ALso sometimes they hide behind the glovebox…you open the glovey…and then unhinge the box door…and it can be right there for you…see if its hard to turn by hand…THAT is common…you have to take them a little way apart to lube them…but after that they last forever… ALSO when n IF you find the blower motor…Unplug and re-plug it in like 5-6 X…this cleans the contacts…sometimes fixes this
SO it can be…your blower motor, The speed controller or the blower moto switch… SORRY for the book I just wrote…Just wanted to tell you that story and the thinking behind it, some people like this OTHER hate me for it…LOL…Oh well I type fast what can I say…its EZ
it is infinite control. I did a diagnostic test to see if the control was working and it checked out.
Not sure how you did that but, if you think the test was accurate then the last item in the line is the actual blower motor itself…Not terribly expensive but installation is as difficult as the mfg wants to make it…Incidentally on a Jeep Grand Cherokee for instance…its just 3 bolts on the underside of the blower motor housing in the passenger foot well behind the glove box… May be just as EZ on the Volvo after you drop down that panel that covers everything near the passenger foot well…OR it can be deeply buried behind the dash/glove box… see what you get. Once you get your hands on the thing its a matter of taking out the old and installing the new…its the “installing” part that is the catch
I would guess the solid state speed control module is bad though the input control to it from the HVAC system is ok. The control module uses power transistors to regulate the voltage to the motor.
where is the speed control module located?
I connected the blower directly to 12v d/c current and it runs so, I guess it’s a switch.
I reconnected the blower and found out that it runs if I push down on the recepticle. So it looks like a contact issue or maybe an incomplete ground.