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  #1  
Old 11-16-2011, 03:06 AM
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Location: Pretoria, South Africa
Posts: 53
w140 a/c question

Guys, this is the final problem with my s500, touch wood! with the a/c on the evaporator tends to ice up on long journeys, i.e hour or longer. The solution I use is to activate ec mode until the airflow trough the vents normalize plus minus five to eight minutes and then switch the a/c on again.

I know it is iced up because the airflow gets lower and lower, and should the compressor of and just blow air there is a lot of water comeing from evaporator drain hoses until the evaporator is"defrosted"

Could this be the tempreture sensor inside the evaporator or the climate control module?

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  #2  
Old 11-16-2011, 06:25 AM
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Join Date: Apr 2010
Location: Pretoria, South Africa
Posts: 53
CODES CLEARED

Car is a 1996 s500, I have fitted a new cabin filter last week, problem persits. What I can mention is that I had a high presure hose burst on the compressor, I replaced the hose had the system professionally regassed, problem was present before this. I just pulled the codes useing Jims's procedure, I got a flury of codes almost every code, I then deleted them all, I have driven for 10 minutes and now the only code is E0 13 cannot connect to rear Climate control module, but I do not have rear climate control. Could all this codes befored I cleared them caused some malfunction??

Thankyou in advance!!
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  #3  
Old 11-16-2011, 07:19 AM
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Location: Pretoria, South Africa
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I THINK I FOUND THE PROBLEM!!

OK guys help me out here but I think I found the problem. Just took another drive with the a/c on and set on 20 degrees celsuis both wheels and fan wheel set to auto.

A/c blew ice cold for the whole trip, airflow did vary but air tempreture remained at ice cold, before I left I read the inside tempreture from the climate control display the way Jim said it was 28 degrees celsuis, after the ride with the interior ice cold, the inside tempreture from the sensor at the sunroof switch still read 28 degrees celsuis.

So I gather my inside tempreture sensor is busted sending wrong info to the climate controle module, which in turn keeps the compressor engaged for too long which in turn freezes up the evaporator after some time???

Does this sound logical?
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  #4  
Old 11-16-2011, 11:09 AM
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Join Date: Apr 2010
Location: Pretoria, South Africa
Posts: 53
PLEASE I NEED HELP NOW

I replaced the cabin tempreture sensor. My problem persits, once youswitch the climate control on the compressor kicks in and never disingages, irrespective of the tempreture selected on the wheels.

you can even select 30 degrees celsuis on both the compressor stays engaged but the air gets warmer as the heater cores heat up, should the compressor not disengae when the disired tempreture is reached?

even on 23 degrees celsuis on the wheels the compressor stays engaged, i.e. does not cycle on and off like my c240 does.

does this car have a klima relay or is this a malfunction of the climate control module? where is the module located?

Please i am going on vacation and need to sort this out pronto
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  #5  
Old 11-17-2011, 05:57 AM
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Join Date: Apr 2010
Location: Pretoria, South Africa
Posts: 53
NEED URGENT ADVISE ON SENSOR VALUES

When reading sensor values from the ac lcd panels, I noticed one irregular reading namely coolant tempreture from sensor B10/8, it shows at 8 to 10 degrees celsuis when car is at operating temp around 95 degrees.

I have installed a 1k ohm resistor in parralel over B10/8 in order to let the aux fans kick in earlier, could this resistor mess up the sensor value for coolant tempreture, and could this coolant tempreture reading impair the proper operation of my ac??
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1996 s500
1978 450 slc
1999 C240
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  #6  
Old 11-17-2011, 07:06 AM
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Location: Pretoria, South Africa
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REPORT BACK

I removed the 1k resistor and the sensor value for coolant tempreture displayed the correct tempreture around 95 degrees, for about 7 minutes then it changed to 7degrees and then 10 degrees where it stays??

then also the sensor value for outside tempreture is alwaya 10 degrees celsuis higher that the outside tempreturer displayed in the cluster, what can cause the coolant tempreture to display correct and then change to an absurd value??

also why the difrence in outside temps??
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1996 s500
1978 450 slc
1999 C240
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  #7  
Old 11-17-2011, 10:01 AM
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Join Date: Feb 2007
Location: los angeles
Posts: 814
replace the evapoarator temp sensor, its on the drivers side of tunnel above brake pedal area hieght wise, goona have a 2 prong plug , it common for that sensor to cause what your experiancing, when you find it just pull ouwards ,its curved about 2 inches long , looks like a probe, its plugged into ac/heater box
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  #8  
Old 11-17-2011, 12:59 PM
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Location: Pretoria, South Africa
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EVAP SENSOR

Nulu, thankyou, yes I agree with you but what stopped me from replaceing is the fact that I could get no error code relating to that sensor.

MB Doc, also suggested replacement of the sensor and putting a 1K resistor inline. I am going to try this, should this fail I will swop the control module N22
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1996 s500
1978 450 slc
1999 C240
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  #9  
Old 11-18-2011, 02:27 AM
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Join Date: Apr 2010
Location: Pretoria, South Africa
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AMBIENT TEMPRETURE SENSOR FOR AC

Can someone tell me where the ambient tempreture sensor for the ac is located, logic tells me it should be somewhere near the blower motor or intake cowl.

I am not referring to the ambient sensor for in dash temp display

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1996 s500
1978 450 slc
1999 C240
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