Blowing hot air when on ..volume of air is fine..started weaking and finally no cold air

Low coolant, if there is an air pocket in the engine it will make it to the heater core. Once there , the air coming out is cold/cool. Once the coolant fills the heater core, it gets hot. If the coolant is fine hot or cold, then have the HVAC system scanned.

Yes I am find to drive

Are you sure the relay isn't getting weak? Try swapping with another.

There are many possible causes for this. A good place to start would be to make sure your radiator fluid is filled up to the cold level when the engine is cold and to the hot level when your engine is hot.

Your heater core may be clogged

without hooking up a manifold gauge set to check high and low side pressures it makes it much harder to diagnose. however air and or moisture in the system could cause this as well as a weak compressor. or a partially clogged thermostatic expansion valve. good luck and I hope this helps!!!

sounds like u guessed right blender door is getting stuck motor is weak or mount is cracked

The air doors are controlled by actuators that on of them or so may need replacing.

I would start by changing your thermostat.

Check both heater hoses under hood to see if they get hot, if they do the heater is fine. need to check to see if the selection doors inside the unit are opening and closing.