Understanding idle control w/ Defrost/AC on: 2RZ motor

Hi,

I'm new to Toyotas and recently picked up a 2000 5 lug w/ 72k miles on it. 4 cylinder 5spd. I've read a number of threads on idle issues, but being new to these trucks, I'm still trying to figure out what is "normal". Here's my situation:

When the defrost or AC is on, the idle will jump from 750 up to 900 or so. Seems normal understanding the AC pump is engaged when these functions are on. But occasionally, I'll get an idle closer to 1500 for a bit, only to have it later settle back to 900. This is always at a stop. Depressing the clutch coming into a stop, the idle will often hang in this 1500 zone before eventually dropping to 900. Sometimes it will jump back up to 1500 while waiting at a light and then go back down. Truck runs and drives normally in all other ways. I've got as good as 29mpg on the highway.

With such low miles, I've only replaced the plugs, air filter, and oil/filter at this point. Haven't touched the ICV or throttle body (for cleaning). I'm wondering if there's a dirty connection or sensor that drives the idle control aside from the ICV, but being unfamiliar with these motors, I'm not sure where to start.

Thanks in advance for the help and advice! Hopefully I've posted in the correct forum.

 

Lubricate the throttle linkage lately ??

Make sure the firewall is not cracked where the pedal mounts .

If the engine is warmed up only the compressor cycling will increase the idle

Automatic trans in gear the idle will be higher when the AC cycles

Your not getting the CEL light are you ?

 

My 2000 SR5 also does the same thing when the A/C is running, though I don't think it gets quite as high as 1,500 RPM.

 

Thanks, both of you. Sounds like I'm probably operating as normal.

I'll check the throttle linkage, but I don't see this issue when the AC/Def is not in use.
I do not have a CEL on. Never have.

 

What are we looking at here?

 

Oops wrong thread sorry