R129 Cold air only from heater

johntom

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Hi
i drove my 1995 SL320 yesterday and the heater only blows cold air, the day before everything was fine?
The control unit, temperature selector seams to work and light up etc, is there a fuse?
 

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Duo valves normally stick in the hot mode there is a sensor under the dash that can do this on a 129 there are some threads on this
 
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Tried the car again today, cold air only. However after about 5 miles down the motorway i turned the heater on again and heat came as it should?
something stuck or a loose connection?
 

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I am sure it is the sensor, mine would go cold at times, and we did have a few post on this a little while back.

I am sure that search say 129 sensor would bring the post up from about 2/3 months back
 
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johntom

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Hi
found some posts on evaporator sensor (and the diagnostics), would this be it or are there other sensors involved?
 
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johntom

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Hi
mine was blowing cold air out regardless of the temp. selected, however the fan speed/volume of air was working (the same in both footwells). When i bought the car i was told the a/c didn't work and due to the weather i have never tried it.
How soon should warm air start to come through? not had the car long but i recall previously getting warm air very quickly from a cold start?
 

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The engine temp does need to be over 50C before you will feel it
 
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johntom

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Hi
the temp was around 80 and it was still cold. Is the sensor accessible from the panel below the steering wheel or is it behind the control panel?
 

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It cant be too bad is it cost £90 fitted by one guy,,I will take a look and see where it is
 

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I have found something that I did not know that I had

A self check is built in. with fault code read out in the display

let me have your Email address and i will send it to you :D
 
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r129 Cold air from heater

Hi
i have tried to access the self check on the heater control but i can't seam to get it to work. My car is a 1995 sl320 and has the push button panel with the digital temp in the top left corner. I have turned the ignition on and pressed the 'rest' button for over 6 seconds, but the display dosen't alter from the selected temp? am i doing this right?
The original problem is previously the heater kicked in with warm air after a very short drive from cold, now it takes ages or not at all (temp guage on 80 and still cold) ?
thanks
 

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I fell that this will be that sensor in the heater that affects most 129,s
 
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johntom

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Hi
should the diagnostic check work on a 1995 Sl320? and whereabouts is the sensor?
many thanks
 

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We did have the details somewhere on the forum as it was done a few months back

I will find the position of it for you
 
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johntom

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Hi
any look on the location of the temp. sensor?
thanks
 

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I have not forgotten this, and I will do it, sorry for the delay
 
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johntom

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hi
thanks for your help guys, however i am still struggling tolocate the thing!
Is it the drivers side on uk cars (the picture shows lhd)?
i have the covers off from beneath the dash on the drivers side but can't find the sensor, is it near the footbrake?
thanks
 


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