2001 v70 cabin fan blows constant

[SandCastle]

2001 v70 a/c climate fan blows continuously - drained the battery.
From other postings, I thought it was the climate control unit gone bad. I bought one used (same 9452369 part number) and put it in today.
Applied battery power and the fan came right on again. Took it for a 15-minute test drive, no difference.
Removed the negative cable and pulled the climate control unit.
Then I had the idea of putting the negative cable back on and, much to my chagrin, the fan is blowing again.
With a large hole in the dash where the climate control unit should be. Needless to say, the negative cable is disconnected now.
What the hello is going on with this? Worse, what is it going to take to fix it?
I need to keep the car on the road; any suggestions are greatly appreciated!
Donald

[jimmy57]

The power unit for fan, it is the transistor that the CCM regulates fan with, is mounted with the blower motor and is the usual cause. Since it does it without CCM installed then it pretty much assures it. The fan is fed 12V+ direct so all it takes is that circuit fusing and the fan runs. Not always, but with some regularity, the fan is drawing too much current and it is the cause of the failure. Original fan and 200K mile range means it would not be any waste to replace it anyway.

[oragex]

As above, it may the the resistor on the blower unit, the metal piece with many pins on it. Comes separately but getting the whole blower used is about the same price. This unit has little rust on the center rod, so it should be in good condition.

Again, just a supposition, not a sure fix because when the resistor goes bad it's rather acts like it won't work at all or only at one speed.

http://www.ebay.com/itm/2006-Volvo-S60- ... U9&vxp=mtr

[jimmy57]

On p2's it is not a resistor like on 850's w/o auto climate. Manual or auto climate P2 both use the transistor circuit. Transistor circuit doesn't have 3 paths plus direct with a thermal fuse. What I meant by "fusing" in my reply is that the transistor internally melts and becomes conductive without a triggering signal from CCM. The afterblow functionality on P2 models could cause a full time fan run but the test for that is to unplug CCM and see if fan runs. That has been done here if I read the post correctly.

[SandCastle]

Hey @jimmy57 - thanks. For the transistor circuit - is that replaceable by itself? Or this the "thermistor" referenced in other posts?
I ask because I did purchase a used Climate Control Unit and that unit did not improve the issue; maybe made it worse.
You are correct - the CCU is not in the car, and the fan is continuously blowing. Which part am I looking to replace?
Thanks again, Donald.

[precopster]

It is directly attached to the fan and is crescent shaped with multi pinned heatsink made of aluminium.

[SandCastle]

Thanks @jimmy57 and @precopster I ordered both the fan unit and regulator - replaced these and it looks like we are back on the road! Previous posts about removing the fan - the back-right screw being impossible to get out are correct; I ended up breaking the tab off the old fan housing.
Thanks again for your suggestions.

[abscate]

You can get to that hidden torx screw with a flexible driver, but sometimes the field repair manual calls for other techniques

Its fine with 4 screws.