Aircon Problem

[Brochman]

This may sound daft,but I'm not convinced the aircon on my W124 E280 is actually working. The button marked "EC" on the dash doesn't actually seem to do anything. I don't notice any change to engine revs at tickover when this button is pressed to put the the light on or off. The outside air temperature has been as high as 18C (that's high for the Northern Isles!) but nothing seems to happen. Is there an easy way to test if the cooling is working? I used to have a Vectra and the aircon on that blasted out freezing cold air even in the middle of winter , which is why I'm convinced that this one isn't working.

Any thoughts anyone?

 

[guydewdney]

what style of air con control do you have? wheel or lcd? LCD has self diagnostics..http://www.continentalimports.com/ser_ic40142.html

if not - then stick a thermometer in the vent and turn wheel to full blue, ec light off.

any air con bods can re-fill system - make sure lubricant is added!

 

[Benzowner]

I presume all Mercs are the same, the EC light on is economy which turns the air con off. The light must be on to run the air con. I must admit, I do not find the air con very cold, but certainly comfortable.

 

[nickmann]

...The light must be on to run the air con. ...

I think that should be the other way around - ie light off to run the air con.

EC on = Cooling is Off
EC off = Cooling is ON

EC is EConomy mode. The economy is that the compressor isn't running, so all that is happening is that air is being moved around.

 

[Brochman]

Thanks

Thanks for that - that is very clear.

EC Button Light on - a/c off
EC Button Light off - a/c on

At least I now know whether it should be pushing out cool air or not.

 

[Brochman]

what style of air con control do you have? wheel or lcd? LCD has self diagnostics..http://www.continentalimports.com/ser_ic40142.html

if not - then stick a thermometer in the vent and turn wheel to full blue, ec light off.

any air con bods can re-fill system - make sure lubricant is added!

Its the wheel type. I'll try your idea with the thermometer thanks.

 

[DrNick]

Turn the wheel all the way to the blue (on both sides) so it goes 'click'.

Turn the fan up to a reasonable number (3 or 4).

Make sure the EC light is off.

Wait for a few minutes before deciding if its working or not. My air comes out reasonably cool but not frigid.

When the dials are in the white zone, then the car will put out cold air on a hot day and warm air on a cold day until the 'optimum ' temperature is reached. Moving the dial away from the white adjusts this optimum temperature up or down accordingly, so its actually climate control but without the fan control.

If you are not worried particularly about fuel economy its probably best to leave the dials in the white and leave the air-con on. The car will then set itself to that temperature whatever the ambient conditions.

Push the dial all the way to the blue so it clicks just allows the cold air through. Turn the dial all the way to the red gets you maximum hot air. On mine, there is a big difference between all the way to the red, and all the way but not clicked!

 

[Benzowner]

Yes Nickmann you are correct. I started off the reply correctly then had a senior moment well thats my excuse

 

[nickmann]

... On mine, there is a big difference between all the way to the red, and all the way but not clicked!

That makes sense I think - if you have the dial on red but not clicked then you are telling the system that you want the cabin to be at, say, 28 degrees C. If you click the dial then you are saying you just want max hot air with no temp monitoring at all. Although i wonder why if you set the cabin temp to 28 then why doesn't it just belt out max hot until you get to 28, then back off the output temp to 28 to maintain it. If it did that it would certainly stop my wife wanging the dials from one end to the other of their travel.

It would be interesting to know if there is a cutoff, ie parked in the sun in South Africa, click to red and the system will shut off at say 40 degrees cabin temp or similar?

 

[PJH]

As guydewdney says, it may just need re-gassing.
But it might be the compressor itself, or the clutch mechanism.
Do you have a dehumidifier button above the EC ?
My 280E has different buttons to yours but the dehumidifier is always cooler than using a/c.

 

[Brochman]

I've done the experiment with the thermometer - no change in temperature. I think I've got the de-humidifier button - it's above the EC button and has a rectangle with two wavy vertical lines. The car's goinmg in to the garage to have the seat repaired so I'll get them to check the compressor gas then.
Today has been really warm, so could have done with a blast of cool air.

 

[Paul64]

Very easy check to see if the A/C is working, gas side anyway.... start the engine and set the temps to cold, EC button without the LED lit.
Open the bonnet and look for the gas pipes to and from the compressor - on my 500E they are cadmium plated gold in colour and on the RHS of the engine bay as you look at it.
After a short time, one should be cold enough to cause condensation on the outside. There is also a small glass viewing window in the top of the dryer unit. This should be clear of bubbles when the compressor is running. It will cut in and out quite quickly if the weather is not too warm as it reaches the cut out pressure in a hurry.
The A/C compressor will only cut I (I believe) if the temperature of the car interior requires cold air. If it is a cool day anyway, you will need to push the other button in the heating controls - dehumidifcation - that keeps the compressor in operation, most useful in the case of steaming up during a rainy day.

That's how my system seems to work anyway....

 

[Paul Grainger]

Another simple check....

With the air conditioning switched on (and before the car has cooled to 'setpoint' temperature, or the anti-frost stat has kicked in) just look at the compressor unit. The clutch should have energised, you should see the input shaft spinning.

If its not spinning, you have a problem......

Paul G