Audi Repair: heater blowing cold air, bentley service, a6 quattro

Question
QUESTION: Jan,
  I have a 2001 A6 Quattro with a 2.8. When driving and coming to a stop,even after the engine is warmed up the heater blows cold air. When a load is put back on the engine it operates properly. Timing belt and water pump service was done 25,000 miles ago. I have had the car 2.5 yrs. and the problem has only gotten worse. The car has 119,000 miles on it.

ANSWER: It sounds like your heater valve may be sticking.  Try watching the valve, which is located behind the engine (two tubes 3/4-1" diameter) next to each other one has a valve in it which has a plastic line going to it.  If a second person switches the heater control from hot to cold, you should see the valve operating.  if the heater is functional, both hoses will be hot, when the engine is warm and the valve is open. Let me know,  Jan

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QUESTION: Jan,
  I did not see the valve,the hoses are down behind motor,however both were hot. If the inside vents for foot and dash are open the dash ones run cool. If foot vents are turned off,and dash vents open heat comes out. I think it might be in the car which I don't think is worth taking apart. If I may another unrelated question,I have an oil leak coming from the pass. side rear cam shaft seal. I have the Bentley service manual,but it does not say how to repair or what the torque settings for the bolts which I imaging must be removed. Thanks for any help on this.

        Bob

Answer
The camshaft oil seal is much more work than the valve cover gaskets, which typically leak on this car.  If you are sure that it is the camshaft seal. the torque values for the cam caps is 17Nm, 15ftLb.  They must be tightened down evenly, and after installation of the cams, the engine should not be started for 30 minutes to allow cam lifters to adjust (very small oil orifice) if necessary.  I always rotate the engine by hand to ensure nothing is hitting, as the clearance between valves and pistons is very small.  With reference to your heater problem, it sounds like the temperature control flap is not opening correctly, the control unit is indeed a difficult job.