hey guys i need some help ive got a 1998 audi a3
thats having a few problems,
firstly the heater is blowing cold constantly, ive checked coolant it does need topping up about every ten days, theres no water leaking into footwells so dont think heater matrix is shot.pipes feel warm going in to bulkhead but they're not hot to touch. also theres a slight smell of fumes come thru air vents when heater is on, engine never overheats but i have noticed it drops to around 60 on temp gauge when driving along, this never happened before gauge always stayed around 90 also its seems a little sluggish now.....

any ideas guys (sensible ones preferably)