Have 2003 Explorer that when turning on heater get a tapping or flapping noise

Your 03 Explorer has motors on the side of the heater box that control the detent and the temperature and they are separate motors so you need to figure which one controls the detent which is which level the air travels to.

Sounds like the gear to adjust the flaps is broken or misaligned. May have to disassemble dash to discover problem.

Try starting the truck so it makes the noise.
Then switch the air control to "fresh".
If noise stops, it is probably the motor that closes flap to recycle the cab air.
It would be found under the dash, under the glove box, & would need to be replaced.

Check the blend door cable for proper attachment to the control panel and to the blend door. Try opening the door manually to see the you can get hot air out. If not, the door may be broken inside the heater box. If yes, correct/adjust the cable attachment for proper operation.

REMOVAL & INSTALLATION
1990-97 Passat Models
Install the cable ends marked with a white or blue band to the control head assembly. The cables must be attached to the control head before connection to the system air flaps.

1. Remove the climate control head from the center dash assembly to access the control head cable ends.
2. Remove the lower dash panels as necessary to access the cable lever arms.
3. Attach the airflow distribution cable (cable 2) to the airflow distribution knob's lower control lever.

This cable can be identified as follows:
Operates the mode/central air flap Cable has a black sleeve and is 25.0 inches (634 mm) long Cable is marked with a white band

1. Press the cable's sleeve against the control head stop and install the retaining clip.
2. Attach the temperature control/air blend cable (cable 3) to the air temperature knob's control lever.

This cable can be identified as follows:

Operates the temperature control/air blend cable air flap Cable has a blue sleeve and is 21.0 inches (535 mm) long Cable is marked with a white band

1. Press the cable's sleeve against the control head stop and install the retaining clip.
2. Attach the airflow distribution cable (cable 1) to the airflow distribution knob's upper control lever.

This cable can be identified as follows:


Operates the footwell/defroster air flap Cable has a black sleeve and is 37.5 inches (954 mm) long Cable is marked with a blue band

1. Install the cable such that the blue band is over the retaining clip mount and install the retaining clip directly over the blue band.
2. Install the climate control head.
3. Set the air flow distribution knob to defrost.
4. Connect the longest airflow cable (cable 1) to the footwell/defroster flap lever on the heater's air box.
5. Press and hold the flap's lever toward the retaining clamp perch and install the cable retaining clip.
6. Set the airflow distribution knob to the Vent position.
7. Connect the short airflow cable (cable 2) to the central/mode flap's lever.
8. Pull and hold the mode flap's lever away from the retaining clamp perch and install the cable retaining clip. Check the operation of both air flaps making sure they can be heard contacting their stops.
9. Set the temperature control knob to full cold.
10. Connect the blue-sleeved cable (cable 3) to the air blend/temperature flap's lever.
11. Pull and hold the mode flap's lever away from the retaining clamp perch and install the cable retaining clip. Check the operation of the air blend/temperature flap making sure it can be heard contacting the stops.

Fig. Side view of the control head and cable location. 1. Footwell/defrost flap cable-2. Air distribution cable-3. Temperature control flap cable

Fig. Temperature flap cable location and adjustment

Start by checking your battery voltage. Do you have a volt meter??

their is a flap inside of the vents that is not being turned. so the cable connecting the heater nob to flap might be disconected. or the flap is broken

Yes it could be a ventilation flap motor,
remove & check ono by one motor and check that wratling noise then u can find out wich flap is broken.

It sounds like blower motor has failed. Motor is located behind glove box on lower part of heater box.

sorry never had one apart sao i cant finger anything in particular,remove any coversa and put head under and have a look,could be a faulty climatic computer or just a rubber pipe come off eoither on teh inlet manifold or on a flap operating mechanism

a ha... the motor which control the flap is machanically jam or the motor is malfunction..
u can heard tap tap tap tap tap sound once u on ur car... after few minutes the sound will dissapear...
try to open the cover and check if the motor is function properly or machanically jamed..