yes.

Thank you. I confirmed that today. I had to remove the hoses to take out the heater.

And, to confirm my previous doubt: Yes, it is necessary to remove the AC unit in order to remove the heater.

Thank you all for your help.

Diagnose this issue guys. Heater is not working. Everytime I turn the heat on no heat but I lose coolant and I have to deal with the annoying dash alarm going off. Think is I have no idea where the coolant is going. Its not coming into the car and nothing in the engine bay. The only other thing I can think of is between the fire wall but. If it were there wouldn't it be coming into the car an soaking the carpet. So is my heater core bad or plugged do I just have a leak somewhere.

IDEA'S

Air pockets in the heater core?

Make sure to squeeze all of the coolant hoses in the engine bay while the car warms up and keep filling the radiator. When the thermostat opens the level in the radiator will drop significantly - you have to fill the radiator again.

I have flushed the system and refilled. I even use the overflow coolant bowl that attaches to the filler neck allowing bubbles to come out of the system threw the filler neck. Still no heat. I should also say I have done a rebuild on the engine and the heat didn't work then either so...bad core?

Have you confirmed that the water control valve and the air mix motors are working?

i believe so...

Yup....that's what I missed, thnx...popped the windshield defroster panel and there was the forgotten connection. Much better! Now...to get the antifreeze out from underneath the carpet and dry it out...

I know the motors work I have checked that all the doors open and close and the blower fan works. The heat switches from cold to hot you can tell, I will get slightly warm air coming into the car but then after that its mostly just cold still and never gets hot.

I don't know if the water control valve is bad or not I haven't had a chance to check it out.