Hi,
I recently got my A/C serviced in anticipation of driving in TX this July. After the service we noticed that when the high idle circuit kicks in with the A/C compressor there is a high pitch whistling that rapidly accompanies it. The whistling disappears when the compressor switches off but the source of this sound seems to be the cylinder head.
I have not gotten a MIL status light yet and my understanding is that modern sensors will detect a vacuum leak very accurately so I'm thinking its not any vacuum lines. A/C works fine as well, no rapid cycling of the compressor clutch to suggest a problem with the expansion valve.
I've read elsewhere that the 1ZZ FE makes alot of strange noises. Could this be a noise that's inherent in the engine design? Could the high idle be activating the VVT solenoid (for pollution control) and what I'm hearing is oil moving through the actuator?
Thanks for your thoughts.