Rep Power: 0

The car is a totally stock 2002 Honda Civic LX, D17A1 engine, auto trans, 202,000 miles, head gasket recently replaced, runs EXCELLENT.
The A/C system in the car works GREAT except there is very low airflow (volume) from the dash vents (especially the center vents) even with the fan set to MAX.
I already replaced the cabin filters.
I suspect that one of the blend doors inside the dash is not opening completely.
How can I test the operation of the blend doors without removing the dashboard?

 
Rep Power: 512

Center vents come off with the radio bezel. Pretty easy to remove.

Side vents are also pretty easy, but I don't remember how to do it. It's been a long time since I did that, and it was to take a dead grasshopper out. Lol

Edit: oh wait. Just realized you were talking about the one that shifts from floor to face vents. Disregard

 
Rep Power: 99

Is there a noticeable difference when you turn the fan speed **** to increase? I mean does the blower clearly spin faster to move more air?

If so, where is the air going if not the center vents? Can you feel ample airflow at the windshield or floor vents?

I've noticed with my 05 EX Civic that even if the blower is OFF and I change the mode selection, I can faintly hear the blend door moving if it is quiet enough. Or it may just be the temp control blend door that does that...can't remember.

Hopefully your problem is a faulty switch. If it's the blend door then I believe that would be a big job to fix. I think the whole HVAC box would have to be removed.

 
Rep Power: 134

I believe there is a troubleshooting procedure you can perform on the HVAC that tells you a DTC and what component of the HVAC system is malfunctioning. Either air mix control, mode control or evaporator.

 
Rep Power: 0

This might be helpful

 
Rep Power: 0

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This is not helpful. DTCs are set by the onboard computer NOT by people doing diagnosis.
DTCs relate to the fuel, ignition, EVAP systems, NOT the HVAC system.

 
Rep Power: 134

Here is the procedure to retrieve a DTC from the HVAC system:

The heater control panel has a self-diagnosis function. To run the self diagnosis function, do the following:

1. Turn the fan switch OFF

2. Press and hold the recirculation control switch and the rear window defogger switch down.

3. Turn the ignition switch oN ll

4. Release both switches. The recirculation indicator and the rear window defogger indicator come on. The recirculation indicator goes off 3 seconds later and the A/C indicator comes on. then the self-diagnosis will begin. About 10 seconds later, the self-diagnosis will finish and the A/C indicator goes off.

If any trouble is found. the recirculation indicator blinks the diagnostic trouble code (DTC) to indicate a faulty circuit or component.

If the system is OK, the recirculation indicator stays off.
Here are what the fault codes mean.

7 An open in the air mix control motor circuit

8 A short ln the air mix control motor circuit

9 A problem in the air mix control linkaqe, door, or motor

10 An open or shon in the mode control motor circuit

11 A problem in the mode control linkage, doors, or motor

12 A problem in the blower motor circuit

13 A problem in the EEPROM in the heater control panel; the control panel must be replaced

14 An open in the evaporator temperature sensor circuit

15 A short in the evaporator temperature sensor circuit

In case of multiple problems, the recirculation indicator will indicate only the DTC with the least number of blinks.

In case of an intermittent failure, the heater control panel will store the DTC until the ignition is turned off.