My 2001 Mitsubishi eclipse wants to die when I turn on my air conditioner or defrost.

Idle is controlled by idle air motor and they can get dirt clogged and be cleaned. Of course, all tune up items can also cause this, as well as bad O2 sensor, TPS, EGR, and others.

Clean the throttle body(inside as best you can) clean the idle air control motor, and change the air filter if dirty..

Clean the inside of the throttle body as best you can. also the idle air control motor.

Try this.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

When the car is not moving the IAS motor regulates the idle speed. IT has very little to do with the speed

idele position sensor

air conditioning takes a lot of power out of the engine,easiest solution switch it off till the car is moving again

car should have to learn idle situations,this is a good point but hard for it to learn if a problem exsist ,try replacing the idle air controll it may be the colpret

your idle speed too low.take it to a dealer.they have to reset idle.it should be 600-800 rpms.when you turn on air conditioner.the computer steps up idling to keep engine from stalling .your curb idle too low.

will the car stay running if you hold down the gas pedal a little? if it will, check the idle air control motor. it should be on the throttle body.