Hey everybody, I'm a new guy here. I got a question for anybody who can
answer it. I have a 2001 Sport Trac, well when I turn on my heater, idle just
goes crazy. It feels like it wants to shut down, but when I turn it off its alright.
I also here clicking noise in the engine. Can anybody tell me what my problem is?
I need your help. thanks....guitarman_gibson

 

I'll take a stab at it......
Does this car have A/C also?
It sounds like the clicking could be the compressor going on and off.
You could be low on refrigerant (leak).
I'm thinking when you turn the heater on, it's actually on one of the settings that include Defrost, which turns the compressor on, which is a drag on a marginal engine...hence the poor idle. How's it run on open road?

 

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Heater blend door controlled by vacuum. Vacuum canister in place to hold door during acceleration (no engine vac). Look for vac leaks as vac leaks cause poor idle (too lean).