Thanks for the reply

My apologies for not supplying enough info on the vehicle.It is a 1991 w124 230e automatic with 460 000KM on the clock.

I have in the mean time sorted most of the problems.

1- Gas pressure was slightly low.
2- The fan I referred to was the interior fan,not aspirator. The switch contacts was dirty. I cleaned these and it is now working 100%
3-Replaced faulty climate control PC board behind centre console.
4- Replaced stuck heater valve

All seems to be working fine.

Thanks for all the input