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Toyota Service
Toyota Service, Toyota Expert
Category: Toyota
Satisfied Customers: 4912
Experience:  30+ Yrs of auto experience, Award Winning Svc. Manager; Just Answer Customer's Choice Award Winner
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Vehicle stalls at idle. Cleaned and tested IAC valve.

Customer Question

Vehicle stalls at idle. Cleaned and tested IAC valve. Cleaned throttle body. All new tune-up parts. A/C idle up valve tested. Vacuum at idle up valve good. What we have noticed is that the 14 volt signal to idle-up valve lasts only approx 1 sec after turning on A/C, and then drops, zeroing out after another 2 seconds. Is voltage to A/C idle-up valve supposed to remain constant while A/C is on, or is it supposed to drop like this? Adjusting socket head on valve has no effect. There seems to be no effect from idle-up valve. Is there a circuit that we can check that supplies signal to idle-up valve?
Submitted: 1 year ago.
Category: Toyota
Expert:  Toyota Service replied 1 year ago.

Hello. Welcome to Just Answer. Please allow me to assist you. The voltage signal for the AC Idle up valve comes directly from the AC amplifier under the dashboard. Thsi would be form the Light Green wire at Pin 13. Since you have voltage for a second or two, and then are losing this voltage, it would be prudent to check the AC pressures first. If the system pressure is too high or too low, the AC Dual pressure switch may be opening, which would cut the idle up signal. Second, it would also be prudent to ensure that the compressor clutch is rotating/fully engaged. If this is not happening, then the reason for the clutch disengaging is the next task. I will assume that the system is fully charged, the AC dual pressure switch is not faulty, the compressor is engaged. This would lead me to believe that the AC amplifier is the root cause of this issue, as the AC Idle Up valve should be energized whenever the compressor clutch is engaged, and then power off when the clutch disengages.

Expert:  Toyota Service replied 1 year ago.

If you have any questions, please feel free to reply. Thanks