I have replaced the thermostat, water pump, radiator, head and intake gaskets and filters in the glove compartment along with the air control cluster and blend door actuator the one closest to the control cluster. This is a dual system front and rear. the air coming out the front is now cold to cool the air out the back unit is what it should be hot is hot cold is cold. There is another actuator farther back under dash what does this one do? Is there something that fell into the duct system causing a hang up in the door there is a clicking every so often when changing where the air is coming from but not all the time but would that interfear with the temperature is there a possible air bubble trapped in the front heater core?