YES. The A/C will cycle on and off when the heater is on defrost. That stops the A/C compressor from locking up during the winter months.
It is possible a little low on coolant and has an air bubble in the heater core.
The AC and heater are completely different subsystems. The heater relies on heat generated by the engine and circulated by the engine coolant (radiator fluid) while the AC uses a belt driven compressor and separate fluids. Their only normal commonalities are the blower motor (which you said works), the ducting and the control head.
There are 2 fans that would be running while you are driving and that is normal... the compressor fan if you have the air conditioner running and the radiator fan runs to help keep the radiator cool while the engine is on.
Yes, it will run when in defrost or mix.
Provided the heater is of a low wattage it should not affect normal running of the car
It is normal for a little vibration with the air conditioning on due to the compressor working , fans on , and engine running a little warmer. On at least 92-96 Toyota's the fans automatically come on when the ac is turned on
Check your temperature gauge. If it shows the engine is running in the normal range then there could be a problem with the "air door" that controls how much air is brought in through the heater core. Or the core itself is plugged and needs to be flushed out. If the guage shows the engine is running cold , then you should have the thermostat replaced.
does the compressor run????ARe they equal pressures?if yes to both...compressor(most likely). If no to comp. running normal....the compressor has to run
That is normal operation.
If your engine coolant temperature gauge is indicating that it is running much cooler than normal ( it sounds like the engine cooling thermostat is sticking open / not closing completely ) which means you need to have the thermostat changed. You should consider if have good heat from your heater and if your check engine light comes on.
160 to 185 degrees F is normal running temperature.
If the engine is getting up to normal temp, the heater core might be plugged. Heater core is not plugged and normal operating temp!