I've done a search but could find no explanation, can someone tell me what the EC button does, as it seems to do nothing whether it's on or off in my car, the light comes on when depressed, but nothing seems to happen.

Cheers George

I now know what this buuton does it serves no other purpose but to switch off either of the other two aircon buttons, this can be done anyway by half depressing the other buttons so no lights show on any of the 3x buttons. Now I have a useful propose for this econo button, to turn it into a proper econo switch. What can be done is going to save fuel costs and some brake pad wear and give you more power.

This is how it's done, get a switch that's operated by vaccum and it will operate via the econo switch, and brake the contact of the aircon switches when the vaccum is low (when your accelerator pedel is partialy depressed or pressed to the floor) this way your aircon switches off when you need power from the motor for going uphill or overtaking, but comes back on again when the vaccum is half way on your vaccum gauge or fully to the left. this way you will save petrol and have more power for going uphill or overtaking.
This also will save some brake pad wear as when you deaccelerate the drag of the aircon compressor will give more engine braking and save some break pad wear.

It's a win win modification and every thing to do it it accesible in the vicinity of the switches all you need is a $20 adjustable vaccum switch a couple of bits of wire and some switching knowledge to turn the econo switch into something that is useful. Here are two web pages for the type of switch that you need.

http://64.233.187.104/search?q=cache:BkWxzHXRHRYJ:www.autospeed.com/shop/category_706/browse.html+vacuum-switch&hl=en

http://us1.webpublications.com.au/static/images//shop//hi/888800079hi.jpg

Cheers George

The EC button stands for Economy. Quite simply, the fan should work normally at variable speeds to help heat or cool your car, but the air conditioning compressor is not engaged if this switch is selected. Pressing any other switch to the left of the EC button with direct which air vents are used to supply air with the air conditioning compressor engaged.

The fan still operates with the fan speed controls even when non of the 3 x buttons are depress, the only thing this ec button does is to pop out either of the 2x aircon butons and this can be done anyway by half depressing either of the other two buttons, they are mechanical buttons in my model maybe yours are electronic buttons, you talk of the butons being to the left or right of each other in my w124 300e 1987 they are all vertical maybe the mod will not work on your model.

Cheers George

G,

Look underneath your accelerator pedal , Is there an electro-mechanical switch
under the upper portion? If so you have a kickdown switch, which shuts off the compressor under hard acceleration.

Wrong, this switch purpose is to jump the transmission back into 1st gear from standstill instead of taking of in 2nd gear from standstill. It does not disconect the airconditioning compressor. A simple try out is to press the button while the aircon is operating, it does not switch it off.

Cheers George

According to my owners manual, the EC switch controls the source of cool air. In other words, when the EC switch is depressed, the automatic climate control uses outside air when cool air is needed instead of turning on the AC compressor. This results in greater economy since the AC compressor never comes on. All vents continue to operate as usual.

All the other control buttons , those with a solid white downward pointing arrow, utilize the AC for cool air when the climate system decides to cool the car instead of heating. Of course, the far left button is for the defroster and the AC is always used for quick defogging.

The climate control system was pretty confusing at first. Pressing a given button did not necessarily do anything depending on what the climate control "brain" decided needed to be done. There seems to always be a time lag between the car being too hot or cool and the climate system trying to do something about it.

Your idea of a vacuum operated switch to turn off the AC under acceleration is a good one. Years ago I saw an accessory switch for sale which did that. Since I often drive underpowered Volvos, I've thought of trying to find or make such a switch. What is needed is a vacuum operated switch mounted to a T in a vacuum line which comes off of the intake manifold. This switch would be wired in series with the AC compressor clutch or maybe use a relay. The switch would need to be adjustable to find the right vacuum level for the AC to cut out. As you point out, when you press down the accelerator, the vacuum decreases and the AC would be disconnected.

This set up would not improve economy much but would direct more engine power to the wheels. If you proceed with your idea, please let us know how it works.

__________________
1986 300E
1993 Volvo 940 Wagon
1984 Volvo 240 (daughter's)
1976 Dodge 1/2T pickup, gas hog

Look at my first post the 2 links give you what vaccum switch you need, then all you do is go to the back of the speedometer and put your T line on the Economy Gauge, it's all there within 12inches of each other, and make the EC switch with the vaccum (adjusted for where you would like it to cut in), in series for the 2 other compressor switches.
So the compressor only activates at half or no throttle or when braking, good for the ecology, good for fuel saving, and good for brake pad wear.
Simple for $20 you have it all.

Cheers George