Heat issues

Here we go for the short version as I am on my phone.
Car started to overheat- got to almost half on the gauge and I had no heat in the car.
replaced the thermostat with a failsafe 180* stat. no change.
Flushed the core and broke the restrictor in the process. All good with the core. Hose splice works fine.
Next thought was the pump......until I found that when in vent mode I get LOTS of heat. Turn on the defrost - or anything with the AC - and I get cold air again.

fan on low I get heat with AC, the faster the fan, the colder it gets.

can I just remove the AC relay and disable the compressor? Is there a plug on the pump?

I NEED THE DEFROST as it is now getting to low 20s here.

TIA

Robert

You don't happen to have a spare control head laying around do you?

It's odd that the car itself got hot.

The a/c compressor does have a plug if worse comes to worse.