Fan blower

We have a 1994 four door cavalier. We had the thermostat replaced as the heat was not kicking on nor was the fan until well after the car was running. This is still happening. The fan will eventually come on, but not when it is needed for defrosting. I would take it in but don't want to pay for repairs I don't need. I honestly don't think the thermostat was the issue.

Any ideas. Is it wiring or the fan going bad??

Thank you

Just fixed one today with the same problem..
It was the ground contact on the blower motor.
The shaking and warming up of the engine made the connection better....

What about the fan itself? Took mine out of a 94 Lumina APV and it checked out fine so I put it back in. A while later problem was getting worse so I took the fan out, took it apart and found the armature was very worn and the brushes were virtually nonexistent. Changed the fan, and no probs since. About $80 for the blower. Good luck!!
Jeff