Volvo Repair: 1989 760Turbo Wagon Heat/AC Blower, climate control system, automatic climate control

Question
Car has 240,000 miles.  Last year, I replaced fan blower motor myself with unit from Advance Auto.  Had to reverse polarity on the plug to make it run the correct rotation.  Has been working fine for over a year.  Recently started making noise like a stick or something was rubbing on the squirrel cage.  Was going to take it apart to clean out.  Last night I was on a long trip and was increasing and decreasing fan speed to try and blow out whatever was stuck in there.  Then, the speed control stopped working.  It would work on the same speed on all settings, including zero, except on max when it would speed up slightly.  So it seemed like it was stuck on speed setting 4 out of 5.  However, when I shut the car off the fan motor continued to run.  I had to remove the fuse to get it to stop.  I am assuming that there is a relay somewhere that has stuck closed since power is going to the fan motor with the ignition key removed.  I probably cooked this relay with the adjustments or heavier load on the motor from the debris.  Is this the likely cause of my problem?  If so, where is this relay located and how do I identify it?  If there is another cause, can you point me in the right direction, please?  This car has the automatic climate control system.  I noticed tonight when I took the car for a short errand that when I replaced the fuse (#28) the A/C switch light (blue) was blinking on and off slowly.  When I shut the car off and restarted, it wasn't blinking but would illuminate when pushed and extinguish when released.  The system had been working perfectly except for the blower cage noise until a week or so ago.  Thank you in advance for any help you can provide.  Pete

Answer
   Pete, the power stage probably is bad. When that light is blinking, it means the system has detected a fault. There is a way to retrieve codes, but I don't remember it because I always used VADIS. it's almost always the power stage.
   It's solid state and either behind the glovebox or behind the control head under the dash. They are not cheap.

Mark