Olpos

my brother has a 92 300E,,,,I have a 90 300 E. This has happen to us and then goes away. Mine come out cool in the center and hot on the ducts going to the side windows.

On the few times it happens I shut the car off, turn on and its gone for weeks. Maybe hitting the 0 climate control of the pushbutton and then pressing another selection would do the same?

Not a solution, just a possible bandaid. I beleive you have a gate hanging up or binding from lack of use, but more opening and closing will one day stop it all together. So , if this happens mid season I would say the gate is sticky from being in heat mode for the winter. So it sticks in the early transition to summer and then goes away. If it happens mid season, then my guess is that it is close to being toast. My hope is that both our cars have a glitch and we just have to turn off and then on a few times as the summer starts to work the gate lose.