2009 galant, added coolant.. still blowing hot air

It sounds like your thermostat is stuck closed. Your thermostat also acts as a heater valve to let hot coolant go to your heater core to blow hot air if your thermstat is stuck close it prevents your coolant to run through your radiator to cool down and to blow hot air from your heater core. A way to check to see if your thermostat is working while its at operating temp feel the bottom and top radiator hose if your lower hose is cold and top is hot your thermo is stuck closed but be careful hoses might be very hot

You need to fix the coolant leak, then refill and bleed cooling system, then you will get heat and cure overheating problem too

The AC Light flashing can be caused by numerous things, some of which can be very difficult to answer without proper testing. The first thing you need to ask yourself is, "Is the A/C working?" i.e. Is the actual compressor switching on and off. If you hear a clicking sound when you first initialize the A/C that means the clutch is engaging. If you hear a second click, that would be the clutch disengaging for what most likely would be a system shutdown. My first step would be to check the hoses for any signs of obvious leaks, and then check the pressure. Make sure that you check the pressure after the clutch has engaged, and that you have the Max A/C setting enable with full fan.

Depending on the mileage of your car and the usage, it may be something as simple as a recharge. The 09 Galant uses R-134a. If you find that your pressure is dropping continuously, you should take your vehicle in for a thorough A/C analysis, as these are not situations that the average home mechanic can handle easily without the proper equipment. The A/C unit will need to be tested for major leaks, and will most likely need to be discharged and recharged professionally

first I would look under the hood with the a/c on to see if the compressor clutch is working, if not it could be a simple fix by adding refrigerant, if you have a leak then, you need to take it in and have a test performed on it, most shops have a dye that they put in to see where the leak is

What engine 2.2 or 2.4 ?
Important: On vehicles equipped with the 2.4L engine, open the coolant air bleed valve. The coolant air bleed valve is located on the top of the thermostat bypass pipe/heater pipe assembly. Close the valve once a continuous stream of coolant is expelled from the valve.
Does the cooling fan come on ?
Notice: When adding coolant, it is important that you use GM Goodwrench DEX-COOL™ coolant. If coolant other than DEX-COOL™ is added to the system, the engine coolant will require change sooner: at 50 000 km (30,000 miles) or 24 months.
Close the radiator drain ****. Remove the drain hose.
If previously removed, install the engine block drain plugs.
When installing the drain plugs, use pipe sealer GM P/N 12346004.
Important: On vehicles equipped with the 2.4L engine, open the coolant air bleed valve. The coolant air bleed valve is located on the top of the thermostat bypass pipe/heater pipe assembly. Close the valve once a continuous stream of coolant is expelled from the valve.
Fill the surge tank to the base of the filler neck.
Start the engine with the pressure cap off. Let the engine run until the upper radiator hose starts to get hot.
If the coolant level in the surge tank is low, add the proper mix of coolant until the level reaches the full cold line.
Important: After servicing the cooling system, and if the vehicle is equipped with an intermittent low coolant light, an occasional low coolant light may be encountered during some extreme driving maneuvers. This complaint should be eliminated by removing the surge tank cap and adding coolant to a level just at or above the full cold line when the system is cold.
Install the cap onto the tank with hand tight pressure.

Did you replace the thermostat? If it is stuck open the coolant may not get hot enough to be effective.

you might want to check the valve that lets hot coolant into the heater core. good luck!

think it needs more coolant added when engine is cold

if you had any kind of heat before you started,you probably have air trapped in the heater core in the the rest of the coolant system

could be waterpump?
i was going to say rad fan,but if so heater would be hot.
lack of coolant will make heater core to blow cold,if engine heats up with full coolant,usually means poor or no circulation.
water pump?
run engine with full coolant,at operating temp.with rad cap off and look in rad cap hole and see if there is movement of water inside rad.
[rad fan will not come on if water is not circulating through rad water pump?]