2015 Subaru Forester - AC Clutch does not re-engage after WOT

Working on a 2015 Forester with the non turbo engine. The vehicle has a MAP sensor, an accelerator pedal position sensor and a mass air flow sensor. I did not see a TPS in the wiring diagrams. Is there a forum member that knows which sensor communicates the WOT condition to the ECM?

The Forester disengages the AC clutch at WOT but the AC clutch may take up to 15 minutes to re-engage. Turning the vehicle off and on resets the sensor and the AC clutch engages normally again. I'm thinking the sensor communicating the WOT condition is not communicating the non-WOT condition to the ECM when the owner lifts off the pedal. I road tested the vehicle confirmed the condition.

All pressures are good and the system works great when the compressor is running.

Drive by wire systems use the accelerator pedal as an input into the ECU/ECM. The ECU/ECM controllable the throttle

Can you manually activate the AC clutch when it decides to stop working?

Thank you for the info. I'll pull that sensor and test it. I can also try powering the AC clutch directly when it's not working.

No codes? Misfires? Wondering if it's missing at WOT, and shutting the compressor off is a programmed response. :huh:

What kind of scan data do you have available from the ECM and the A/C Control Panel?

The wiring diagram shows that the ECM, pressure switch and A/C Control Panel are directly involved in energizing the control side of the A/C relay.




Depending on how accessible the pressure switch is, I'd be tempted to watch pin #2 and #4 while doing a WOT run. Pin two is some kind of normally closed, pull up power supply to the control side of the A/C relay, AND an input to the A/C Control Panel. Pin #4 is a pull down input to the ECM directly.

Just to close the loop on this one...

The problem is being caused by the AC compressor clutch/coil. Because it's an intermittent problem it was difficult to test. I was finally able to detect battery voltage on the feed wire to the coil and the clutch was not engaged. The air cap is out of spec.