Guess: Best Guess is defrost or AC are on and the engine is having trouble running the compressor. This is common on these cars when they have another fault with the way they run. Second best guess, The engine has a run problem, and the extra load causes it to be worse.
why 2003 ford focus stall when air conditioner is turned on
Yes.
No.
No.
it might be your throttle
mostlikely the jeeps been off road and mud and grass, or muddy water got to your heater core area,letting the smell airgate through out your heater when turned on.
Its power source is not turned on or it requires repairing.
new heater
Replace the fuel pump. I had an S-10 that acted similarly - turned out it needed new spark plugs and wires.
Have you turned the control from Pilot to On? Have you increased the temperature setting?
The heater core of a 2004 Chevy Tahoe is used to provide a source of heat to the cabin. When the heater is turned on, air is blown across the heater core which is constantly supplied with hot coolant from the engine.