My 1984 300D is doing a really strange thing of late. The A/C will suddenly blow hot air. Not warm air or ambient outside air, but HOT air. Heater core on a 100 degree day air. Really unpleasant little shock when it's 95 outside. It will work just fine and then poof suddenly your a schnitzel in a big German convection oven. I can't figure it out. Sometimes it starts out that way when you start the car but other times it will just suddenly blast out hot air in midstream.

Any ideas? Most of the time if I turn the ACC system off for a period and then restart it the situation will resolve itself.

Thanks in advance for any help.

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'84 300D Turbo Black w/Tan (104k)
'94 GMC K1500 Z-71 (198k)
'96 Ford Explorer V8 AWD (178k)
'51 Ford 8N ( about 2000hrs)
'98 English Setter "Jade" (10k foot weary, bird finding miles)