A/C Problem – Where is the Evap Temp Sensor Located W202- C230k - 1997 RHD ??

[bernardtam]

I am having the A/C problem in my car for 2 years now. One day she works just fine while when she is moody, don’t work at all !

Usually, when I switch A/C to position 1 while set the temperature selector in the white range, the blower motor will generate a tornado inside the car, once I switch it up to 1.5 or 2, it will quiet down and work as usual ( well, not really, only on her good day ). Sometime there are hissing noise coming out from the vent. Yesterday, the blower motor didn’t work at all and there is no air coming out from A/c whatsoever. Since I brought the Evaporator Temp Sensor quite a while ago, may be the first thing is to replace the “Free” part and see if it can fix the A/C problems or not ??

Any help or advise is appreciated !

 

[mattkh]

Hi
Investigate the blower issue first.
Replace the pollen filter.
Remove the leaves from the vents.

 

[bernardtam]

Hi
Investigate the blower issue first.
Replace the pollen filter.
Remove the leaves from the vents.

Hi Mattkh,

Yes, already clean the Blower Motor and the sensor speed controller ( The aluminium casting ) and replaced a Carbon Filter too 2 days ago, so, I don’t think my A/C problem is related to either of these 2 suggestions !

What should be my next step ?

 

[mattkh]

Hi
Can you put up a picture of the dashboard showing the a/c and blower controls knobs

 

[bernardtam]

Yes of course and there you are :

 

[mattkh]

Hi
Thank you for the photo.
I notice you have separate temp controls for the driver and passenger.
The symptoms you mentioned, are they on both sides or only on driver's side.

 

[type49]

The temp sensor will not regulate fan speed at all. Your fan speed problem is either regulator, fan or very rarely control panel.

 

[bernardtam]

Hi
Thank you for the photo.
I notice you have separate temp controls for the driver and passenger.
The symptoms you mentioned, are they on both sides or only on driver's side.

I always have the same setting on both side and the A/C problems are on both side and the Symptom is identical too !

 

[bernardtam]

The temp sensor will not regulate fan speed at all. Your fan speed problem is either regulator, fan or very rarely control panel.

Hi & thanks Type49 !

Fan ( Blower Motor ) should be good but for Speed Regulator and Control Panel ( the switches ??), I am not too sure !

Any simple tests that I can tell which part is wrong ??

 

[mattkh]

Hi
What normally goes wrong is the so-called DUO Valve.
Can you see it in the engine compartment ?

 

[bernardtam]

Hi
What normally goes wrong is the so-called DUO Valve.
Can you see it in the engine compartment ?

DUO Valve ??

Is that associated with the Blower Motor at all ?? It's under the dash in passenger side in my car.

 

[mattkh]

Hi
I dont think is connected to the blower BUT
it definitely controls the water going in to the heater matrix.
It is normally in the engine compartment, two small coke tins with lots of 1" water hoses.

 

[eric242340]

Hi
I dont think is connected to the blower BUT
it definitely controls the water going in to the heater matrix.
It is normally in the engine compartment, two small coke tins with lots of 1" water hoses.

The duo valves are used for heating and after-running cooling and nothing to do with the air con. On this model, ive often found the fan speed control switch to be faulty. This is my view, but there are so many other parts that can affect the system in this way. The fan speed switch will cause the system to act as you have described and sometimes just by touching the switch (gently move it) the air will stop blowing.

 

[bernardtam]

The duo valves are used for heating and after-running cooling and nothing to do with the air con. On this model, ive often found the fan speed control switch to be faulty. This is my view, but there are so many other parts that can affect the system in this way. The fan speed switch will cause the system to act as you have described and sometimes just by touching the switch (gently move it) the air will stop blowing.

Hi Tacher !

yes, I really mean it as I know nothing about the car A/c at all ! I think you are talking about the common fault with the Blower Regulator ?? If so, I just have a new one ( K.A.E.) with me, I am going to change that and work on some other aprt on my car tonight and let you know the result !

Thanks

 

[bernardtam]

The duo valves are used for heating and after-running cooling and nothing to do with the air con. On this model, ive often found the fan speed control switch to be faulty. This is my view, but there are so many other parts that can affect the system in this way. The fan speed switch will cause the system to act as you have described and sometimes just by touching the switch (gently move it) the air will stop blowing.

Hi Teacher !

2 days ago, a A/C specialist fixed the A/C, my A/C console was dead and have to replaced with a new console, wow, 2 days before I fixed the car, my console is still working fine back then and I should have save myself US$600 for a new console. The mechanics explain to me that the compressor kicks in and stay there too long and kill the console. I don’t quite understand what they said but they are honest people. I replaced a reconditioned compressor and it is working quite ok now. But they warn me that the Blower Motor and Blower Regulator are almost there and I better replace them ASAP !

Well, tonight I did the following :

1) Replace the seal from the washer reservoir to the pump. Aged seal just broken when the shop replace my A/C compressor.
2) Replace a new K.A.E. Blower Regulator.
3) Television suggested me to strained and closing a bit on the socket for the combo relay. I found there is not much I can do about it as all the connectors were in solid round shape. Not much hope about improvement but will see how my intermittent wiper goes.
4) Vacuumed the car, which I did not do that for over 6 months.

I hope the wiper will back to normal !! If not, I will try to find out the diagram on the combo relay and concentrate myself on the connectors that are for the wiper control, then do the exercise television suggested once again

 

[mick mc carthy]

HI

I think i'm having the same prob as you, if you turn your fan on to any setting and press the rest button see if you get hot air blowing out it would be like setting one on the controler.

 

[wscheffer]

The evaporator temp sensor on my W126 is down by the expansion valve it hooks over to the transmission tunnel and back to the rear of the evaporator housing. This places it right between the evaporator and the heat exchanger.

I imagine that most of them are in similar design.

Hope This Helps!

 

[bernardtam]

The evaporator temp sensor on my W126 is down by the expansion valve it hooks over to the transmission tunnel and back to the rear of the evaporator housing. This places it right between the evaporator and the heat exchanger.

I imagine that most of them are in similar design.

Hope This Helps!

Hi William,

Please note that you're talking to an idiot here !! lol !

So, should it be behind the CD, Temp control panel ??

Thanks

 

[wscheffer]

Yes, but it is accessible through the side leg cover in the foot well of the center console.

The easiest way to find it is to open the hood and see where the two A/C lines go through the firewall into the passenger compartment. Then remove your panels where your feet and legs go.

Find the A/C lines they will go from the firewall into the bottom of a square metal block and exit out the top and back into the evaporator housing.

The square metal block is the expansion valve and the sensor should not be far from it.

 

[bernardtam]

Yes, but it is accessible through the side leg cover in the foot well of the center console.

The easiest way to find it is to open the hood and see where the two A/C lines go through the firewall into the passenger compartment. Then remove your panels where your feet and legs go.

Find the A/C lines they will go from the firewall into the bottom of a square metal block and exit out the top and back into the evaporator housing.

The square metal block is the expansion valve and the sensor should not be far from it.

Thanks wscheffer ! It is RHD here in Hong Kong and I opened the panel both on the passenger and driver side but still can't find it ! Strange ! Some people say that it's behind the temp control / CD panel ! Will take a look when I am free.

Thanks but never have a code for evap temp sensor in fault ! May be it is in good working condition !