2004 camry 4 cyl. low idle vibration with a/c on

I would assume that a normal idle speed should be around 750, my engine is idling at around 400- 500rpm.

Try cleaning the throttle body.

I have cleaned the throttle body with very little improvement it was not that dirty after all. what other components can cause low idle and vibration. I am not a mechanic, but i do most of the maintenance work on my car trying to save a buck or two. Thank you for your help.

Any other suggestions on the low idle problem? Also is it ok to replace convensional ATF fluid in the transmission and power steering with synthetic atf like mobil 1 ATF? Or is there a better synthetic atf other than Mobil 1 AtF that I should use? And how can I do a home power steering flush while replacing the fluid without hurting the system? Thanks again.

You can tell if the IAC does not function properly if there is a drop in idle with ac on. The IAC valve should compensate for extra load on the engine . With your idle at 400-500 rpm turning the ac on will likely stall the engine. You may have possible drag in the belt system. Synthetic ATF fluids I've used on Toyota's would be Valvoline Max Life, never tried Mobil one trans fluid, but their oil is very good. The easiest way to home flush the power steering fluid would be to suck the fluid out of the reservoir and refill with new fluid, run and then repeat several times. Flush is used as a magical word sometimes in the auto repair industry, no machine will exceed the pressures the pump creates or do any special cleaning.

Thanks again, I will check for drag on the belt and adjust if necessary, my camry rpm dial has 4 marks before the 1000rpm mark, 3 small marks a space and one more mark just before the 1000rpm mark. I assume the first 3 marks represent 300rpm and the mark just before the 1000rpm is 750rpm. My idle is usually between the 750 & 300 marks. Should I also check for vacuum leaks and if so how should I go about it? My toyota manual suggest dexron III ATF for power steering and T-IV ATF for Transmision. After your suggestion, I check the Valvoline Website and MaxLife® DEX/MERC ATF synthetic recommends that it can be use where both fluids are specified, the Dexron III ATF & T-IV ATF so I guess I can use it in my transmission and in my power steering without any problems. Would you agree? And thanks again for your patience and time.

I have a 2005 Corolla S that I just replaced the belt tensioner on and now it has the shakes at low idle. When driving or if the fan comes on when I am sitting still, the idle is higher and there is no shake. What would make it do that. I was very careful to follow the instructions when replacing the tensioner, including priming the piston on it.