Equinox overheating

So my 2006 Chevy Equinox was overheating. I had no heat or AC, blower would not turn on. Temperature gauge would go up and down. On idle it would shoot all the way up. When I shut the car off both fans in front would turn on and stay on for about 5 minutes.
I was told to change the coolant temp sensor. I did. Then it worked perfectly. The blower started working. Heat and AC worked. Fans would not turn on after car was shut off. It drove perfectly for 5 hours... then suddenly all symptons came back.

Now, I dont know if it was a coincidence. But I parked the front end on top of a curb, because I wanted to bleed air out of the bleeding screw on the engine. (was suggested to me because coolant tank would bubble a bit). After I loosened screw and car was parked on curb, I turned car on and when I turned heater on it did not blow air again. I purged some air and screwed the bleeder screw back on. Then I drove it and the blower never turned on again. All the symptons returned as before. Fans turn on after car is off, temp gauge goes up and down, on idle it shoots all the way up, on highway up down, etc...
Someone suggested I change thermostat, I did. Same problems. Bought another coolant temp sensor, this time nothing changed.

Can anyone suggest why car worked fine for 5 hours then suddenly went back to old problems even after changed sensor again and thermo?

Are we sure the system is full, both at the radiator and the expansion tank? Bubbles in the system are either entrapped air, or could be a head gasket leaking compression.

If the system is completely full, cold, it may be worthwhile to borrow a pressure tester to see if the system will hold pressure.

When you bleed it, make sure heater is on.

Your blower motor has nothing to do with the coolant sensor, thermostat, coolant level, etc., ........it's a separate problem altogether....

Next time it doesn't run, give it a wrap with the handle of a screwdriver....

Were you losing coolant prior to this? If yes you have a coolant leak....could be external(pump, radiator, hose, etc.) or internal(intake gasket, head gasket, etc.).....

Any kind of a leak, will create an air pocket, which will restrict coolant flow and cause the vehicle to overheat.....

It worked for awhile because you cleared the air pocket.....then once the air pocket developed again, the car overheated....

Did you ever replace the coolant lid on the reservoir? The coolant may boil prematurely if the cap isn't holding pressure. This may subsequently cause steam/air pockets to develop.