I have a problem with the air heating. Even at the highest fan setting it blows like low setting. It is hot no problem with the temperature. But, air coming out is very week. When I increase the fan speed, I can hear that it is becoming stronger but the air coming out is not. The ice takes few ours to melt. Why would that be? 3 months ago I replaced the cabin filter. And 4 months ago, timing belt and other belts in that area are replaced. And I had a sequezing sound from the power steering since then. Do not know whether they would be related?

 

The latter are not related. You most likely have a mode control problem.

If you hear the fan speeding up, then air is coming out. WHERE, is the question.

1. Make sure that you have the mode selected to vent (arrow pointing at the upper body). Turn fan up. Does it still not come out of the vents?
2. Turn it on full blast and then figure out if it is at the feet, vents, or defrost (likely not if it is not melting ice). The mode control motor is what controls where the air comes out. If it does not respond to your inputs when you change modes, it is likely bad.
There are ways to run diagnostics, but start with that for now.