Hello,


I have been reading through a number of posts here, trying to determine what is wrong with my Accord. Thank you for all of your help so far!


I managed to figure out how to show the DTC codes for my HVAC, and it looks like codes A, B, C and D came up. So that leads me to believe that there is something wrong with the electrical circuit related to my HVAC temperature sensors. What should I be checking and/or replacing? Is this something I could remedy on my own?


The last mechanic who looked at my vehicle wanted $1000 to tear apart the dash and see if it was the blower door.


Thanks!

 

1. Does the car have navigation or not? The auto climate control system is slightly different between the two.

2. What symptoms are there?

 

DTC's should be a 1 or 2 digit number from 1-15.

Following is sequence to extract codes:

1) Turn switch Lock to On
2) Turn blower to OFF, Temp control to Maximum Cool, and Vent air outlet selected.
3) Turn switch from Lock to On
4) Press and hold recirculation button, and w/i 10 secs press/release the rear window/mirror defogger 5 times.
5) Release recirculation button. Recirculation light will flash twice and then code sequence begins.

Recirculation light blinks the codes; all short flashes w/ 1.5 secs between 1st and 2nd digits of two digit code and 3 secs between successive codes. No A, B, C, D is mentioned in shop manual.

good luck

 

HVAC number trouble codes are for cars with manual A/C. The HVAC alpha trouble codes are for cars with auto-climate control.

 

Please answer:
1. Does the car have navigation or not? The auto climate control system is slightly different between the two.

2. What symptoms are there?

 

Sorry for my delay...thank you for responding! Yes, I have navigation. The air conditioning does not get cold, but the fans work. The heat also does not get hot, but it seems to have very little heat from the passenger side vent.

 

Depending on whether the "AUTO" or "A/C ON" indicator lights up with the trouble code(s) can mean different things. You may have to do the test again and post the results. See attached image of location of AUTO and A/C ON indicators on audio-HVAC sub-display.

Description:
A and AUTO: an open in the in-car temperature sensor circuit.
B and AUTO: a short in the in-car temperature sensor circuit.
C and AUTO: an open in the outside air temperature sensor circuit.
D and AUTO: a short in the outside air temperature sensor circuit.

A and A/C ON: an open in the driver's air mix control motor circuit.
B and A/C ON: a short in the driver's air mix control motor circuit.
C and A/C ON: a problem in the driver's air mix control linkage, door, or motor circuit
D and A/C ON: a open in the passenger air mix control motor circuit.

Note: If A,B,C, D, G, K and the AUTO indicator or A/C ON indicator are on at the same time, it may be an open in climate control unit ground circuit.

Code Description with no "AUTO" or "A/C ON":
A: Climate control unit internal error.
B: Output shaft (countershaft) speed sensor signal error. Check for DTCs in the A/T system and go to indicated DTC's troubleshooting. If no DTCs found, replace the climate control unit.
C: Engine Coolant Temperature (ECT) sensor signal error. Check for DTCs in the PGM-FI system and go to indicated DTC's troubleshooting. If no DTCs found, replace the climate control unit.
D: Communication bus line error.

 

The first three codes show together with the A/C on indicator, (it looks like an L turned 90 degrees to the right). The fourth code shows with neither auto not A/C...

 

Ok, sounds like a problem with the air/mix control motor circuit. Give a little bit of time to get some info. for you.

 

It probably is a bad driver's air mix control motor. It can be tested; but, I'm not sure if you want to tackle something like that with a multimeter, testing equipment, etc.

The driver's air mix control motor is on the left side of the lower center dash area. See attached photo.

To get to it, you have to remove the driver's dashboard lower cover. You just pry off one plastic clip with a screwdriver, and gently pull the cover off the other clip and hooks (the other clip should pull out with the cover). See attached images.

The air mix control motor is held in with three screws.

The Honda part number should be 79160-TA5-A21. Honda list price is $41.85. Part can be purchased for around $30 plus shipping from online Honda dealers; but, the shipping costs will probably make it around the same as list price.