A/C kept running non-stop-2001 E240
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A/C kept running non-stop-2001 E240
Hi,
Can any 1 help me. My A/C kept running non-stop even if I have turn the engine off (key removed). I have unplug power cable to the fan unit beneath the passenger seat dash. Previously the A/C wont even function/response.
Kind Regards,
RMT6668
Can any 1 help me. My A/C kept running non-stop even if I have turn the engine off (key removed). I have unplug power cable to the fan unit beneath the passenger seat dash. Previously the A/C wont even function/response.
Kind Regards,
RMT6668
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From: NorCal
'99 C43, '12 C63, '13 E350, '14 Sprinter
I had the same thing happen on my wife's '00 E430 recently. She had the heater on fairly high and it stayed on when she shut it off. I also unplugged the blower unit to solve the problem temporarily. The permanent fix was a new control unit from Autohaus AZ which was the least expensive place I could find - about $150 if I recall correclty. This also fixed the occasional "racing" iof the blower. Sometimes it would spradically speed up and slow down. Now it's as good as new.
It was very easy to remove and replace. Just pull off the cover under the dash, remove about 4 screws holding up the blower assemply and separate the regulator from the blower itself. Took about 5 minutes.
It was very easy to remove and replace. Just pull off the cover under the dash, remove about 4 screws holding up the blower assemply and separate the regulator from the blower itself. Took about 5 minutes.
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Hi,
Thanks.Is the control unit you mention the same as the regulator. Coz I have alrady disassemble the Blower unit beneath dash the Passenger seat. I notice the Blower cable is connected to a metallic unit (with spike like). Is this the regulator/control unit to replace? Is that US$150?
What you describe on your wifes car is exactly the symptom on mine.
Thanks again
RMT6668
Thanks.Is the control unit you mention the same as the regulator. Coz I have alrady disassemble the Blower unit beneath dash the Passenger seat. I notice the Blower cable is connected to a metallic unit (with spike like). Is this the regulator/control unit to replace? Is that US$150?
What you describe on your wifes car is exactly the symptom on mine.
Thanks again
RMT6668
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I tried to plug in the cable back & it kept going regardless but only air I think. I tried to adjust the thermostat to HOT but it just blow air. I dont think its cold air, may be room temo air? Is that similar to yours?
I am double checking coz some 1 from another forum said may be its the control Unit? Whats your thought on this? I prefer your diagnoses, coz its easier to access & replace.
RMT6668
I am double checking coz some 1 from another forum said may be its the control Unit? Whats your thought on this? I prefer your diagnoses, coz its easier to access & replace.
RMT6668
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Hi again,
Some 1 message me that for the Regulator, I can short test it by simply pushing some sepcific buttons on the AC but he cannot remember which buttons. Can any 1 please help?
Kind Regards,
RMT6668
Some 1 message me that for the Regulator, I can short test it by simply pushing some sepcific buttons on the AC but he cannot remember which buttons. Can any 1 please help?
Kind Regards,
RMT6668
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From: NorCal
'99 C43, '12 C63, '13 E350, '14 Sprinter
I never heard of a method to test the regulator. Not a bad idea if the $150 scares you. From what I've read, however, it's more a matter of WHEN you'll need to replace it than IF you'll need to 
You could try a dismantler for the part. You could probably find it for $100 or so that way, but the condition may be questionable. Maybe you live close by another E class owner who'd let you test with his/her regulator?
You could try a dismantler for the part. You could probably find it for $100 or so that way, but the condition may be questionable. Maybe you live close by another E class owner who'd let you test with his/her regulator?
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I think the fault may be the AC Control Unit & not the Regulator. I have tested using a Mutilmeter on the 3 wires pin attache to the Regulator. Its constantly on 12 Volt no matter what Fan Speed dial switch I turn to. Meaning the Control Unit is constantly ON. Some suspect may be the REST swicth which can only come on with the engine off or the key not in ignition.
I need to access the control unit to check. Will be diffcult & challenging to open/access.
I need to access the control unit to check. Will be diffcult & challenging to open/access.
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From: NorCal
'99 C43, '12 C63, '13 E350, '14 Sprinter
Actually it's a piece of cake to pull out. Grab a set of the radio removal keys off of e-bay for about $20 and they work on the control unit too. It pops right out. I went through this exercise as well. If I have time before we head to the slopes tomorrow I'll check my stuff with a multi-meter as well to see if your behavior is normal or not.
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Thanks for helping check using the multimeter.
But you mention the special key (2sets) to open the casstte player to access to the wooded cover dash. You mention that key to also open the control unit? I thought the key only to open the cassets player to access the screws to remove the other screws parts to access control unit?
But you mention the special key (2sets) to open the casstte player to access to the wooded cover dash. You mention that key to also open the control unit? I thought the key only to open the cassets player to access the screws to remove the other screws parts to access control unit?
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If its a faulty control unit & I bought the car new in Aug'2001, do you think it will still be under warranty?
I will be ashame for Merc to have such a bad quality. If its warranted I will not take the part apart
I will be ashame for Merc to have such a bad quality. If its warranted I will not take the part apart
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Hi again,
I finally manage to pull the AC Control Unit off. Attached are the pics I have taken. Surprisingly with the AC Control Unit disconnected, the Blower still kept blasting away. Is it back to the Regulator or even the Thermo Sensor Switch Faulty?
Can some one pls lead me in the right direction very much appreciated.
I finally manage to pull the AC Control Unit off. Attached are the pics I have taken. Surprisingly with the AC Control Unit disconnected, the Blower still kept blasting away. Is it back to the Regulator or even the Thermo Sensor Switch Faulty?
Can some one pls lead me in the right direction very much appreciated.
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From: NorCal
'99 C43, '12 C63, '13 E350, '14 Sprinter
I had the same result, thus deduced that the regulator had failed. I still haven't taken a multi-meter to the control unit (ours are quite different from one another), but I'm 90% certain the root cause is the same.
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rmt6668
For what it's worth, here's a link that may help you with your diagnostic.
Good luck
http://www.continentalimports.com/ser_ic40142.html
For what it's worth, here's a link that may help you with your diagnostic.
Good luck
http://www.continentalimports.com/ser_ic40142.html
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Thanks,
From the site, its diagnostics for Climate Control or Automatic Control Unit. But mine is a dial or manual type of control unit, like the pic I posted.
SDR,
You still conclude its the Blower Regulator? Should I check the current/voltage of the 3 pins cable running into the Regulator?
From the site, its diagnostics for Climate Control or Automatic Control Unit. But mine is a dial or manual type of control unit, like the pic I posted.
SDR,
You still conclude its the Blower Regulator? Should I check the current/voltage of the 3 pins cable running into the Regulator?
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I will put the switch or control unit back in the front dash. However I notice there 2 white plastic (pencil like) which need to be inserted into the 2 plastic behind the dash. What procedure do I look for, in putting the swicth back?
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Hi,
I finally put the AC Control Unit back in the dash. I have tested the 3 pin wires using a Multimeter.
(1) Test the middle pin with AC switch disconnected--->0 Volts & plugging the 3 pin wire to the Blower turn ON full blast
(2) Test the middle pin with AC Switch connected ----->12 Volts & plugging the 3 pin wire to the Blower turn ON full blast
(3) Test the middle pin with AC switch connected (a) Switch 1---> 11 Volts (b) Switch 2--->10 Volts (c) Switch 3--->9 Volts (d) Switch 4--->8 Volts (e) Switch 5--->5.5 Volts
(4) With Engine On, test the middle pin with AC switch connected (a) Switch 1---> 12.5 Volts (b) Switch 2--->12 Volts (c) Switch 3--->11 Volts (d) Switch 4--->10 Volts (e) Switch 5--->7 Volts
Whats odd is that the Blower keep blasting away with or without the AC Switch connected or disconnected.
But the Multimeter detected 12 Volts in the middle pin when the AC Swicth is connected but 0 Volts when discoonected?
I finally put the AC Control Unit back in the dash. I have tested the 3 pin wires using a Multimeter.
(1) Test the middle pin with AC switch disconnected--->0 Volts & plugging the 3 pin wire to the Blower turn ON full blast
(2) Test the middle pin with AC Switch connected ----->12 Volts & plugging the 3 pin wire to the Blower turn ON full blast
(3) Test the middle pin with AC switch connected (a) Switch 1---> 11 Volts (b) Switch 2--->10 Volts (c) Switch 3--->9 Volts (d) Switch 4--->8 Volts (e) Switch 5--->5.5 Volts
(4) With Engine On, test the middle pin with AC switch connected (a) Switch 1---> 12.5 Volts (b) Switch 2--->12 Volts (c) Switch 3--->11 Volts (d) Switch 4--->10 Volts (e) Switch 5--->7 Volts
Whats odd is that the Blower keep blasting away with or without the AC Switch connected or disconnected.
But the Multimeter detected 12 Volts in the middle pin when the AC Swicth is connected but 0 Volts when discoonected?
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From: NorCal
'99 C43, '12 C63, '13 E350, '14 Sprinter
I'm no electrician (and I don't play one on TV), but this sure sounds like the same problem I had. I didn't spend nearly as much time trying to narrow it down because I found dozens of posts about similar symptoms all attributed to a faulty regulator. Many reported "racing" of the blower prior to absolute failure which is exactly what mine did.
If I understand this correctly, the regulator has to receive the voltage fed from the control unit which varies depending on how high you set it. It then has to feed the motor one constant voltage and one "alternate" voltage which creates the variable speed. It's the difference between these two (+ and -) that determines the speed. When the regulator fails it simply sends a full +12 with no offsetting - to the motor. At least that's what the redneck next door explained
If I understand this correctly, the regulator has to receive the voltage fed from the control unit which varies depending on how high you set it. It then has to feed the motor one constant voltage and one "alternate" voltage which creates the variable speed. It's the difference between these two (+ and -) that determines the speed. When the regulator fails it simply sends a full +12 with no offsetting - to the motor. At least that's what the redneck next door explained
