1994 A6 Avant 2.0 Estate - Problems

[Borog]

Hey, im new to these parts and wiondered if i could get some help.

I have only had this car for 2 weeks and have already noticed a few problems with it.

Firstly, the heater doesn't seem to blow hot any more. It did when i initially drove it from the person i bought it from but it has since stopped. I have been told that replacing my coolant may solve this problem, but i cant see how that would help. Does anyone now of anything i can try to see where the problem is? Oh, and i only have the regular heating system, not the climate controlled aircon.

Secondly, There is a really bad rattling noise coming from the exhaust whenever the engine is running. It doesn't matter what gear im in or even if im moving. If have been told that this is due to the honeycomb? in the Cat has broken. Is this true or is the mechanic just trying to screw me out of my hard earned dough?
In addition to this, there does seem to be alot of excessive water vapor coming from the backend regardless of engine temprature.

lastly, the button on the drivers door, which enables me to lock/unlock all doors doesn't seem to be working, and i cannot find a fuse that would be associated with this? i assume there is one? Does anyone know of a fix for this?

any help would be appreciated.

 

[Rev-head]

Does heater blow at all firstly and is there any feeling in the dials that you are turning anything??

Rattle off exhaust can be anything but to eliminate what it could be check all mounting points of exhaust(were mounts to car) and c-clamps on joins,If it is the Cat the noise will be more predominent from front end ,you can check by starting car up when cold(high revs) and looking under car, the CAT is in line with back of the Front wheels box like if gone you will notice

The (fuse) for the lock on the door i think is a thermo cut-out so it will be the switch on the door faulty not the fuse(as the it will be conected to central locking and that works i take it) easy to replace

Hope this helps