124 Heater gone berserk

[s_markham]

I suspect someone has "had a go" at the heater on my '96 124 coupe. Setting the right-hand control to hot gives me hot air from the left-hand vents, and guess what, the left-hand control gives me hot air from the right! Had the car a year and never noticed it before- always adjusted both sides to the same temp.

Both controls work, but are reversed somewhere - can't be on the pcb that has the control potentiometers on it, must be wiring plugs swapped, but where?

I'd give myself a four spanners Haynes rating if this involves taking the dash apart etc.

 

[Brensbenz]

S,

Different model I know but maybe my saga ("Heater Gone Mental") on this page will help. Best of Luck,
Brensbenz

 

[justin1820]

could be the heater hoses mixed up where the connect to the duo valve by the brake master cylinder, if not just swap the two outer pins in the three pin plug that connect to it

 

[s_markham]

You got it Justin. Someone must have swapped the hoses. Swapping the wires as you say makes it all work - easier than swapping hose connections. Couldn't have been like this since new, could it?

 

[Keith]

hose swapper in Cambridgeshire

i had same problem , a not very good independent merc specialist (so called) managed to replace my duo valve and mix the pipes up. the coincidence is that this particular guy is based near cambridge so maybe he's doing it to every car he comes across. I will protect his identity but will say that i dont use him any more!