Hello
I have exactly the same issue with my '96 850T as New2Volvo2 below...

I had to replace the fan in my '93 a few years back but in that case there were obvious
fan noises and intermittent working of different features of the AC and heat. (ECC)
But in this case... everything works fine when it is working... i.e. all fan stages, direction of heat to floor windshield and car itself... fan works from low to high, thermostat works ... everything is normal.
No nasty noises or anything... except the blinking lights of death (recycle and AC)

And then the next time I get in the car there is nothing... no fan or heat until the car warms up and is moving forward then fan-less heat is distributed wherever the dials are set at.
If stuck in traffic I freeze... going along a highway is ok if not TOO cold outside.

The only question I have is that if it is the blower... then why intermittent? How does it work just fine and then nothing? Is it possible that this is an electrical issue or some thermostat, relay or switch not functioning?
IE a blower moter resistor or some such unit?

Before I take out the blower this weekend (in the cold) I would just like to eliminate any other possibilities.

Your experience is welcomed. Thanks guys.