Morischang

I bought this 2007 RL a month ago. at that time it was hot, so I didn't test the heater, but A/C worked very well.
In Nov, it is getting cold, so I turn the AC ON with a 26 Celcius . but blow only cool air.
so I check the items below.
1. coolant - Reservoir was empty , so I refilled the tank, the symptom is same.
2. heater control valve function: as I check the valve in the engine room. it moved ok when heater On.
3. I checked the air mix motor( I am not sure 100% if it was air mix motor, but when I change the temp setting to Hi, it rotated well) this mix motor was driver side.

what else should I check ? please advise. I thougt the root cause was the coolant. but that didnt' fix it.
strange thing is when I turn the heater on with Hi temp, it blow a little hot air and change to cool air(not cold air). which makes me think heater core have a hot coolant inside.
2nd strange thing is passenser side blow a litte warm air but driver side only blow cool air from the bigining. I don't know why....
I can hear the flap is working when I change the temp setting.

Crashmaster

Sometimes just refilling the reservoir tank will not fill the radiator or cooling system. When you have the heater on, touch the heater hose under the hood. See if it is hot. Let's make sure you have hot water going into the cabin first.

projektvertx

iTrader: (2)

I'd pop open the radiator cap when it's cold. Odds are you probably need to fill it with some coolant.

Morischang

good advice, I also think it will take some time or I need to do something so that hot coolant goes into the heater core.

truonghthe

if everything ele function perfectly check your heater valve, in the TL the valve made by plastic the inside flap broke and never function like it should. You can't see from the outside as the pin does move from side to side but it completely detach from the butterfly valve locate within the valve assembly.

deepa1600

you should bleed the system (open radiator cap and top it up and turn the temp knob to max and turn air off. Then start the engine and let it run until cooling fans come on atleast twice) or maybe you have clogged heater core.