(moving lack of) heat in 81 300D

[thekeeper24]

if anyone can offer some sort of advice, let me know, im @ college right now and too get it looked @ by a (real) mechanic right away would be tough, but i love my car and dont want to have any seriuos probelms. thanks

i have a 1981 300D with the auto-climate control. (the a/c has worked in a few years) but when the the car is idleing and under very low speeds it produces great heat from the vents (in both auto and full fan mode), but when the car starts moving only a cool air blows out of the vents (in both auto and full fan mode) I changed the thermostat 6 mounths ago. any ideas or suggestions will be greatly helpful.

 

[thekeeper24]

answer

the problem was that the "mono-valve" was just worn. its a rubber piece in the engine bay near the firewall, i believe on the driver's side. cost about $99 (US dollars) to fix. just wanted to post this so if anyone else ever has this problem.