I have a 1995 Cadillac Deville sedan . My problem is when I put my air con or heat on sometimes the fan would only work for a few (10) second's at a time , then would not work at all or just on defog position, does anybody now's what it could be .?:confused:

Do you hear the fan running but get no air or does the fan shut off? The reason I ask is that defrost is the default position and that would indicate a vacuum leak. If the fan is intermittent then it is either a bad connection or a bad blower motor which is a common problem.

the fan goes off completely than comes back on for 10 sec and eventualy stops working till I play with the contrrolls it works good on de fog , it starts to act up more if I use the air cond @16 deg c:confused:

That's a wierd one. I'd start wiggling connections at the blower and behind the control panel to see if that has any effect.

I tryd the fan today and it works pritty good on economy and defog but as soon as you put the air con on it starts to act up ,also there's not much heat when you try to put the temp up to 32 deg c just blows slightly warm. do you think the climet controll modual is going ,I'm not shure on what kind of mecanisim it uses on the 95 but my last 1980 deville had a vacume operated system.

Sounds like the blower is working ok. You might start at the firewall on the passenger side and make sure you have vacuum at the supply line. If so, then find the ACM (programmer) under the dash on the passenger side and check all the vacuum connections there. Then follow them to the air delivery doors and make sure all is well there.