Hello all, I got into my Escort van on Monday with the heater blower in position 3 and fired the van up as normal.

Full blow as normal, then about 10 seconds pass and the blowers gradually start to faded to nothing.

Got to work left the van for a couple of hours started it up again and the same again.

This happens every time the van has been left a while and occasionally while im driving the blowers will go full bore and fade to nothing in 10 seconds or so!
It is sooooo anoying and difficult to see through a misted screen! haha.

Any ideas as to what could be the cause?

Any info is much appriciated!!
Cheers.