How To Reset The EC Light On Mercedes?

Some would say that the climate control system is a vehicle’s most significant component. If you get stuck in a traffic jam on a sweltering hot day, you will be hard-pressed to agree. Let us assume your climate control is not working. Now, you surely want to know how to reset the EC light on Mercedes cars.

EC light on Mercedes car appears on the button in the climate control console

Car manufacturers install many controls in the AC system to suit the needs of varieties of buyers and climates. EC mode is one such feature.

What Is EC In Mercedes?

The EC symbol on the button stands for ‘Economy’. Economy mode lets the automatic climate control work without switching the air conditioning ON. It recirculates the cold air already in the car, decreasing the demand for the compressor. As a result, it saves fuel. EC mode may appear as the AC OFF mode in your car. Even if that is so, they perform the same function.

The ‘Rest’ button, on the other hand, is a fantastic option during winter, when you visit the store for a few minutes. Turn the engine off and press the button. The system will pump hot air into the car while the engine is not running. It will shut off by itself if no residual heat remains or if the battery drains too low. Rest mode does not work with the engine switched on.

Depending on the design of the car, the EC and REST functions may combine into one button. In this case, the car’s computer decides which one is employed when.

What Does The EC Light Indicate?

The tiny indicator tells us that the economy mode is ON, and thus, the compressor is not running. The car is keeping the cool air inside but not cooling it any further. So, if you cannot turn it off, you have a severe problem on your hand. Since the climate control is in EC mode, the compressor will never start. EC mode is equivalent to switching off the compressor, after all.

It could be an electronic fault in the circuit board of the controls. However, this light also comes on in case of anything wrong with the air conditioning system. Typically, a persistent EC light indicates a low refrigerant charge or a defective pressure sensor. Forcing the compressor to run in such a scenario would damage it. That is why the computer shuts it down.

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Diagnose Why The EC Light Is ON

What information can you gather from the console of the climate control system? The computer provides you with the error codes for whatever fault has occurred. There is a short series of steps to enter the diagnostics mode. After that, you can view the error code and the reading value on the display. The Mercedes model we demonstrate the process on is a 1999 E320.

Once you have diagnosed the problem and found out the error codes, you can fix what is wrong.

Can You Reset The EC Light On Mercedes?

Yes, of course. If you know the reset process, you can reset the control system any time you wish.

1. A Quick Trick

If you are sure that the compressor has no problem, there is a quick trick to turn off the EC light. Follow the steps in the video below to reset the light on your car. Before you begin, turn the AC on both sides to HI. You will not require any tools for this procedure, just the car key. The demonstration is on a Mercedes CLK W230.

While the trick is a success on the CLK 55, W140, W230 and W320 models, it may or may not work for the 2002 C240, 2001 W208, W203, and W210 Mercedes cars.

Most importantly, keep in mind that this method does not fix any defect in the air conditioning system. If the EC light comes on by itself after a few days, it is best to diagnose the climate control system for any faults. One can obtain the error codes via a process we have discussed earlier.

2. How Do I Reset My Climate Control?

If the thermostat in your climate control system does not sense the temperature, you cannot get cool air. It does not matter how far you turn down the target temperature. Thermostats are usually durable and reliable. That is not to say that one will not break down once in a while.

resetting the thermostat may reset the EC light on your mercedes car

When the thermostat is not functioning, resetting the control system is the first course of action. However, be aware that resetting the controls will also remove any stored error codes. That means if you take the car to a service centre later, they will not manage to diagnose any problems before the reset. This action is the second method to reset the EC light on Mercedes.


3. Another Way To Reset the EC Light

If you have a different model of the Mercedes car, the AC reset technique may be different. This process marks the third method to reset the EC light on a Mercedes.

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Step 1: Insert your Mercedes key into the ignition and turn the ignition cylinder to the second position. This point is as far as the key can turn without cranking the engine.

Step 2: Press and hold the defrost and recirculated air buttons simultaneously.

The defrost symbol looks like a windshield with three lines going through it. Meanwhile, the recirculated air button resembles a car with a curved line inside it. Press and hold the two buttons for about 5 to 10 seconds, or until the LED lights on both buttons start flashing.

Step 3: Wait for around 45 to 60 seconds until the LED lights stop blinking. Then, turn off the car.

Step 4: Wait patiently for another 60 seconds. Now, you can restart the car. You have reset your AC system, and with it, the EC light as well.

Recharging the AC Refrigerant

As we said earlier, the EC light can come on if the refrigerant is low in your car’s AC. If that has happened to your vehicle, you are in luck because we know how to refill the refrigerant. You will need to buy a refrigerant refill kit available at both brick-and-mortar automobile stores and online ones.

the refill comes in a pressurised bottle with a connector hose

The steps to refill the AC refrigerant (R-134a Freon) are straightforward. Before you begin, you must switch on your engine and let it idle for a few minutes. Turn on the AC at the lowest temperature and highest fan speed. Follow the detailed steps in the video to complete the refill process.

Note: The low-pressure side of the AC unit comprises the wider tubing. Be careful not to open the high-pressure side.

The pressure gauge on your refill kit may look different. Don’t worry. Thoroughly read the instructions on the back of the pack or in the accompanying user’s manual. It usually explains the operating method well.

When the engine is OFF, the pressure gauge will read an extremely high pressure. That is normal. The correct pressure reading appears with the AC switched on. You may need to hold the bottle either upright or upside down, according to the kit-specific instructions. Keep an alert eye on the pressure during refilling.

In some kits, the pressure gauge only works when the bottle’s nozzle is closed. So check the gauge without pulling the control trigger. Below is a guide to the pressure levels. If your kit is different, check the chart on its back instead of this one.


Following the above steps will help you to reset the EC light on Mercedes cars. The procedures are more or less straightforward. Although, each involves a series of steps to attain the goal. You can complete these steps from the comfort of your home. You probably do not need the advice of a professional mechanic. However, feel free to contact one if you so wish.

Good luck fixing your AC.

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