idling problem on 99 Auto

I recently bought a 99 automatic model and it runs great but when the aircon is switched on, it idles very low, almost stalling the engine. With the aircon switched off, it idles 100%. The car idles fine when it is cold and the rpm is still high, but as it warms up, the problem becomes more noticeable.
Any ideas were to look?
Sias
99 Ford Escort ES auto

IAC Valve

IAC Valve


Concur. It was a part of a similar problem I had.

Thanks, I have found more posts on the subject and I will first try to clean the valve before replaing it.
Sias