AC stays on even when ECon is switched
08-06-2008, 05:54 PM
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86' 300E
AC stays on even when ECon is switched
I have a '86 300E with earlier chasis number.
Recently I decided to dump some money to get my AC working. The mechanic replaced the leaky compressor and sealed everything up good added R12. So now AC works well. The problem is that AC seems to be on all the time even when the Econ is turned on.
This means the compressor is working full time and robbing power from my car.
I was told it may be the Control Unit - but what is and were is this unit located? Why would it be stuck on instead of off? Are there other possibilities?
I know that there is also an AC relay part# R1140-12156 is this it?
Any help would be greatly appreciated. This forum has saved me tons with knowledge on various fixes already so thanks a ton in advance.
Recently I decided to dump some money to get my AC working. The mechanic replaced the leaky compressor and sealed everything up good added R12. So now AC works well. The problem is that AC seems to be on all the time even when the Econ is turned on.
This means the compressor is working full time and robbing power from my car.
I was told it may be the Control Unit - but what is and were is this unit located? Why would it be stuck on instead of off? Are there other possibilities?
I know that there is also an AC relay part# R1140-12156 is this it?
Any help would be greatly appreciated. This forum has saved me tons with knowledge on various fixes already so thanks a ton in advance.
08-06-2008, 08:57 PM
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95' AMG SeeThreeSix
The control unit is the unit in the car with the climate selector buttons, in the middle console. It's right in front of you and you didn't even know it! 
as for the relay, its referred to as the "KILMA" relay and is located under the hood on the passenger side behind the battery. Be sure that you grab the right relay the other one not labeled "KILMA" is your fuel pump relay.
as for the relay, its referred to as the "KILMA" relay and is located under the hood on the passenger side behind the battery. Be sure that you grab the right relay the other one not labeled "KILMA" is your fuel pump relay.
08-07-2008, 04:24 AM
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86' 300E
Can the control unit be bad if most buttons work as expected?
As a follow-up - I thought the unit is just a set of buttons, and all the other modes seem to work well and as expected. Has anyone ran into a similar situation and replaced the control unit? Is there a way to test if indeed it is the control unit?
Thanks in advance.
Thanks in advance.
08-07-2008, 09:09 PM
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w211 & w124
Mine does the opposite, the heater stays on full blast no matter what you do. I was told by my mechanic that I most likely need to replace my control unit as well. Anyone done this before or know of a way to just disable everything. I'd rather it just all turned off permanently.
08-08-2008, 10:26 PM
#5
Mine does the opposite, the heater stays on full blast no matter what you do. I was told by my mechanic that I most likely need to replace my control unit as well. Anyone done this before or know of a way to just disable everything. I'd rather it just all turned off permanently.
Just pop out your CD player, pull off the wood face plate in front of the buttons on the Climate control and pull the unit out after unplugged the (3?) power plugs. Just pop open the cover with a screwdriver and resolder the connections looking for any burned ones.
I know that after I did that, it fixed the heat problem with mine too. Its probably a 40minute job if you do it carefully (which I recommend).
08-26-2008, 09:11 PM
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w211 & w124
I had the same problem on my TE. The easiest fix for that is to take out the Climate control unit and resolder all the connections.
Just pop out your CD player, pull off the wood face plate in front of the buttons on the Climate control and pull the unit out after unplugged the (3?) power plugs. Just pop open the cover with a screwdriver and resolder the connections looking for any burned ones.
I know that after I did that, it fixed the heat problem with mine too. Its probably a 40minute job if you do it carefully (which I recommend).
Just pop out your CD player, pull off the wood face plate in front of the buttons on the Climate control and pull the unit out after unplugged the (3?) power plugs. Just pop open the cover with a screwdriver and resolder the connections looking for any burned ones.
I know that after I did that, it fixed the heat problem with mine too. Its probably a 40minute job if you do it carefully (which I recommend).
Sorry for the late response but thanks for the tip. I'm going to give this a try when I get home. I just fixed my dryer so I feel like MacGyver right now...lol.
