Strange Cooling Situation on W124 300D

[i-osprey]

On my '93 300D I have consistently had some issues with running too hot and some strange issues with the HVAC.

I have replaced both electric auxiliary fans(they are working fine), the radiator, fan clutch, water pump and thermostat.

I have also switched from the green stuff to Zerex G-05.

Off and on I have had some strange activity from the A/C.

Today, like a few other days in the past, when the A/C stops cooling once the desired cabin temp is reached it doesn't just shut down the cooling it actually starts sending HEAT into the cabin.

It does this from the two outside vents while the center vents remain cool.

I also noticed that today it was 85-87F outside and my coolant temp was almost to 110C at highway speeds with the A/C on.

When the A/C cycled off I would get heat in the cabin immediately and my coolant temp would then drop almost immediately.

My question is whether or not those coolant temps are normal and whether there is something linked between the heating system and the engine cooling system that could be causing this.

I will say that this usually happens for a few days after I go through the car wash.