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Can you figure this one out?

I have a 2004 Mitsubishi Lancer ES (110,000 miles) that is working perfectly with just minor, small hiccups. A few months ago I took the temperature control console off (the giant plastic piece on the dashboard that has the ac/heater controls and knobs) to replace the wires because the fan level knob was stuck. That was successful.

However, a few weeks later the AC button is stuck on (green light on). The AC light will not turn off no matter what. I’ve tried to take the plastic piece apart and even unplugged the console to take a look at the actual button itself and it all seemed to be alright (im no mechanic). I’ve tried pushing it a hundred times, in different sequences, anything you can imagine - will not turn off. As a result, we have no heat.

Was it my fault? Did I do something? I don’t know. What do you gentlemen think? I’ve been told that the blend door is stuck but this is a Mitsubishi and every part of it screams “Don’t touch me!” so I’m slightly scared of going too far into the dashboard. Please help, winter is coming and my wife will need that heat. Thank you much!

You may not have reconnected the temperature cable correctly. I can’t say why the compressor light won’t turn off but it won’t affect the heat output much.

this ... Mitsubishi ... screams "Don't touch me!"

One thing for certain, this problem will be difficult to fix without touching the affected parts. It reminds me of a neighbor I used to have who seemed to constantly be tinkering with his car in his driveway, but never seeming to fix anything. As far as I could tell he never actually removed any part from the car, just stood there with a screwdriver in his hand looking at the engine. His solution – when his tinkering didn’t work and the engine finally wouldn’t start – was to have a tow truck come by and pick up the car and take it to the shop.

I presume what you mean however is you hope to find some help from somebody here who has actually solved this exact problem before. I presume you are not in the USA because winter isn’t on its way here. Mitsubishi’s are not common cars in the USA. If you get no satisfaction here you’ll probably need to ask at a Mitsubishi specific forum.

The problem is most likely with the heater/AC ECU.

The entire HVAC system is electronically controlled. And the system takes commands that you put in the heater/AC ECU.


Is the system set so the defroster (demister) is now on? If it is the AC will be on, too. Turn off the defrost and look again. You might get lucky.