99 TC blower problem- unusual

[barrelboy]

I have a 1999 TC that has an intermittent blower problem.
1. The fan will not come on at any speed in manual unless the system is in AUTO )see #2)
2. When the system is in AUTO it only work intermittently, meaning that sometimes the system works (AC & heat) in AUTO and sometimes not. No real logic to it. When the system decides to work it works fine but only in auto. When the AUTO IS working the manual blower fan operation will still not work.
3. I tried running the diagnostics test but got no codes.

Any advice would help.

[Towncar]

Mine also had intermittent problems until it failed completely.

On mine, the huge transistor came un-soldered inside the Blower Speed Controller. It took it out, re-soldered it with a good quality solder and it's been fine for the following 10 years.

[barrelboy]

turns out the blower motor was bad. works great now