1998 V70XC. My heat started acting up today. It was set on high and wasn't on at all, then it came on but the fan was slow, then it would go faster, slower, and stop intermittently. It never did get back up to full speed.I tried all the different settings and that didn't change anything. I took out the climate control fuse and reinstalled it and that didn't do anything. The fan seems quiet, just the slightest hum at its slowest possible speed. Any ideas? I didn't find anything searching the forum, and it has been around 0 degrees here at night in frozen NY, so I hope to be able to fix the heat.

There is a rehostat, resistor, burried next to the fan which has a tendancy to burn out after a few years. It costs about $100 at the cheap places. Now that I am back from NYC, it will warm up again soon.

Klaus
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Volvoless. Sold the R. There is now a void...

Also, when you said buried next to the fan, you did mean the blower motor fan?

If you are good at contorting your body in unnatural positions, then the knee bolster doesn't need to come off. The resistor pack is stuck into the air flow duct coming from the blower, it helps cool off the pack.

Klaus
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Volvoless. Sold the R. There is now a void...

Thanks for the info Klaus. Any idea what it, or its containment looks like? I am going to go outside and try to find it. And I hope your right about the NY cold!

Take a look at his, it is for an 850 but close enough:

http://volvospeed.com/Repair/pdash850.php

http://www.fcpgroton.com/product-exec/product_id/31845/nm/1998_2000_Volvo_V70_Turbo_2WD_Blower_Motor_Resistor_models_with_Climate_Control/category_id/78

Klaus
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Volvoless. Sold the R. There is now a void...

Klaus, I was told that when the switch is set to the highest setting that it bypasses the resistor, and that it would be the blower motor that has gone bad if it still doesn't blow on high. Do you have any knowledge about this?

The resistor is used to control the fan speed in all settings except for max. In auto mode, all fan speeds are controlled through the resistor.

When you turn the engine on, the ECC goes through a self check. The fan should briefly run at high, then turn itself down to low (assuming you have the settings on auto). If the two switch lights on the ECC unit do not blink about 20 times, all systems have been checked and no faults stored.

There are 2 fuses for the blower, a 25amp for speeds 1-3 and a 30amp for high. check both before doing anything else.

You stated that the blower does turn. Is the cabin filter clogged with dirt, making the fan work too hard?

It could, indeed be the blower motor that is going bad. The test is to supply the motor with 12V and see if it turns rapidly and freely. Or try turning it by hand and see if it spins nicely. If you hear noise while trying to turn it or it will hardly spin, the bearings may have died.

Klaus
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Volvoless. Sold the R. There is now a void...

I just checked the fuse panel under the hood and I found 2 25amp climate control fuses, both of which are not blown.

With the fan set to high(not on auto), the blower does turn sometimes, at times it will completely stop. It goes in and out, but never gets up to full speed. This all started only 2 days ago, before which everything seemed fine.

I am sure I need to replace the cabin filter, but I dont think that correlates to the fans speed issue?

I did just order the blower motor from fcpgroton.com. I didnt have much of a choice because I really need heat to be able to see out the windshield. Its supposed to stay below zero here for a few days next week. If it turns out not to be that, I have the part for another time. I will try to send 12v directly to the fan, but I will have to find a spot to put the current into the circuit. If I expose the rheostat on my way to the blower motor I will start there with trying a direct shot of current to the motor.

I just wanted to close this thread out with the results. I decided to change the blower motor because I already ordered it. When I took out the existing motor the cage spun completely fine, at which point I thought "oh crap, it must be something else", but in the end it turned out to be the brushes in the motor. They must have gone bad, because the new motor fixed the problem.