AC Off vs EC Rest?
Thread Starter
Junior Member
Joined: Aug 2016
Posts: 39
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W203 220 cdi
AC Off vs EC Rest?
My w203 2003 C220 has AC off option on the control panel, i have noticed some other older or newer w203 has EC Rest or EC instead of AC off!
Does this mean that my vehicle has no residual heating option when the engine is off?
Also how long does it take for your vehicle to reach over 80 degree engine heat on a 17-20degree weather?
I think mine either has a thermostat problem or something else is wrong coz it takes some driving to reach around 75degree.
Many thanks
Does this mean that my vehicle has no residual heating option when the engine is off?
Also how long does it take for your vehicle to reach over 80 degree engine heat on a 17-20degree weather?
I think mine either has a thermostat problem or something else is wrong coz it takes some driving to reach around 75degree.
Many thanks
Junior Member
Joined: Aug 2008
Posts: 31
Likes: 2
GLC300
Yes, some models have the EC/Rest button.
When the engine is running, pushing EC/Rest turns off the AC compressor, EConomy mode is on and the top LED turns on.
When the engine is turned off, pushing the same EC/Rest button turns on residual heating and the bottom LED lights up.
My W203 heats up in minutes in winter time, so if yours takes a long time (please define "long") then you may have a thermostat leak or failure.
When the engine is running, pushing EC/Rest turns off the AC compressor, EConomy mode is on and the top LED turns on.
When the engine is turned off, pushing the same EC/Rest button turns on residual heating and the bottom LED lights up.
My W203 heats up in minutes in winter time, so if yours takes a long time (please define "long") then you may have a thermostat leak or failure.
Thread Starter
Junior Member
Joined: Aug 2016
Posts: 39
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W203 220 cdi
First, the EC button is not a residual heat button----if the EC button lamp is lite it, means that your compressor is off---there is a separate button for the residual heat option plus you must have a functioning coolant circulation pump.
Regarding your coolant temp question----you have an issue,replace the thermostat!!
Regarding your coolant temp question----you have an issue,replace the thermostat!!
I didnt know that it requires an additional pump for the "Rest" but now i know mine does not have it.
Thanks man
Thread Starter
Junior Member
Joined: Aug 2016
Posts: 39
Likes: 0
W203 220 cdi
Yes, some models have the EC/Rest button.
When the engine is running, pushing EC/Rest turns off the AC compressor, EConomy mode is on and the top LED turns on.
When the engine is turned off, pushing the same EC/Rest button turns on residual heating and the bottom LED lights up.
My W203 heats up in minutes in winter time, so if yours takes a long time (please define "long") then you may have a thermostat leak or failure.
When the engine is running, pushing EC/Rest turns off the AC compressor, EConomy mode is on and the top LED turns on.
When the engine is turned off, pushing the same EC/Rest button turns on residual heating and the bottom LED lights up.
My W203 heats up in minutes in winter time, so if yours takes a long time (please define "long") then you may have a thermostat leak or failure.
Thanks
Last edited by GjBW203; Sep 15, 2016 at 08:51 AM.
Junior Member
Joined: Aug 2008
Posts: 31
Likes: 2
GLC300
Well you could feel (carefully so that you don't get burned) the hoses or measure their temperatures. If the hoses (and rad for that matter) get warm shortly after the engine has been turned on, then the thermostat might be open.
Mine went to 180F in just 5 minutes of driving this morning (mid 60's outside temp), so you may very well have a thermostat that is stuck open.
In regards to the Rest function, that doesn't use a circulation pump, it just takes advantage of the fact that the coolant in the system is hot and it will turn on the heater fan at low speed to transfer some of that heat into the car. As coolant cools off during this process it will circulate within the system due to convection.
Mine went to 180F in just 5 minutes of driving this morning (mid 60's outside temp), so you may very well have a thermostat that is stuck open.
In regards to the Rest function, that doesn't use a circulation pump, it just takes advantage of the fact that the coolant in the system is hot and it will turn on the heater fan at low speed to transfer some of that heat into the car. As coolant cools off during this process it will circulate within the system due to convection.
Newbie
Joined: Aug 2020
Posts: 1
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c240
Issue with heater control
Yes, some models have the EC/Rest button.
When the engine is running, pushing EC/Rest turns off the AC compressor, EConomy mode is on and the top LED turns on.
When the engine is turned off, pushing the same EC/Rest button turns on residual heating and the bottom LED lights up.
My W203 heats up in minutes in winter time, so if yours takes a long time (please define "long") then you may have a thermostat leak or failure.
When the engine is running, pushing EC/Rest turns off the AC compressor, EConomy mode is on and the top LED turns on.
When the engine is turned off, pushing the same EC/Rest button turns on residual heating and the bottom LED lights up.
My W203 heats up in minutes in winter time, so if yours takes a long time (please define "long") then you may have a thermostat leak or failure.
MBWorld Fanatic!
Joined: Feb 2006
Posts: 1,489
Likes: 110
From: WNY
2005 w203 C230
Yes.
HVAC CONTROL is built date dependent. It may work, and you just relearn how to use A/C. And it may not work. Ensure you normalize the flaps holding front defrost and recirculate.
STF. Especially for those of use that did the digital swap.
HVAC CONTROL is built date dependent. It may work, and you just relearn how to use A/C. And it may not work. Ensure you normalize the flaps holding front defrost and recirculate.
STF. Especially for those of use that did the digital swap.
