Help!! My 2011 MC hatchback R56 has developed an unusual twist on the A/C problem where it blows hot air instead of cooled air.

The car is always parked on the street (historic district built before autos and garages) but in all these years no matter how high the built-up heat inside, things cooled down quickly inside.

Now, however, the A/C is fine when I first drive for the day. But if I park, say, and go grocery shopping for a half-hour or more, on my return the air blows hot — hotter than the outside temp. But if I wait for an hour or so and drive again, things are back to normal.

The dealership found the freon was low, so they recharged the compressor and brought the freon up from 45 to 90. But when I stopped at a store on the way home, the hot air blowing returned.

i’ve taken some advice from this forum, like opening windows and the moonroof briefly to help clear out the built-up heat before getting underway. (It HAS been murderously hot in the DC area this month.). But nothing helps — and yes, it occurs regardless of whether recirc is on or not. It feels like something clenches up if I make multiple stops and restarts, but with a longer wait like an hour or two whatever is hosed up relaxes and the A/C works.

I’m not a gearhead but I would appreciate any suggestions about what else could be going on, since I have a long road-trip coming up and my baby needs to chill.

Thanks!

Leslie