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W140 S600 1994
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43 Posts
Discussion Starter · #1 ·
Hi,

I do not have any heat for the front seats, the rear heat is working.

When i first started driving the car there was no heat at all - i did the diagnostic of the A/C and found a open circuit in the CTS (coolant temperature sensor). After changing the CTS the rear heater started working.

(the CTS failure could be because of the car almost overheating- and new radiator installed. The shop didnt fill any coolant/water in it so got hot again before being filled with coolant/water - could this influence the heating?)


I get plenty of air (and cold A/C) through the system.

The duovalve makes noise and gets hot when I hit REST after turning of the engine, but never any hot air inside the car (except rear heat).


Mads
 

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Premium Member
SL55, 300SE, GL450, Daytona 955i
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10,293 Posts
Hi,

I do not have any heat for the front seats, the rear heat is working.

When i first started driving the car there was no heat at all - i did the diagnostic of the A/C and found a open circuit in the CTS (coolant temperature sensor). After changing the CTS the rear heater started working.

(the CTS failure could be because of the car almost overheating- and new radiator installed. The shop didnt fill any coolant/water in it so got hot again before being filled with coolant/water - could this influence the heating?)


I get plenty of air (and cold A/C) through the system.

The duovalve makes noise and gets hot when I hit REST after turning of the engine, but never any hot air inside the car (except rear heat).


Mads
if you manually override the center vent to blow hot air, do you get any warm air...

genreally speaking, this is a duo valve problem, stuck closed... what you need to make sure is getting hot is not the valve itself, but rather the 2 lines coming out of it.
 
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