Are you sure the A/C system is not overfilled? Check to see if the compressor clutch is disengaged when it runs hot like that. If the compressor is not running when warm air is being blown, it could be that the pressure after the compressor is too high, causing the pressure switch to disengage the clutch.
While driving, it's possible that the additional airflow is cooling the compressed R134a in the condenser much faster, thereby keeping the pressure low and preventing the pressure switch from tripping.
This is just a theory, but it's worth checking out. If you can easily recreate this while idling, you can have a shop hook up a manifold gauge set to monitor the pressure while the blown air becomes hot.
__________________
2012 Mercedes C63 AMG P31 Sedan, ROW, aFe, Eurocharged Dyno Tune. 438WHP/415WTQ
2010 SOLD: 40th Anniversary 370z
|