Mechanics

A/C TROUBLE SHOOTING HELP NEEDED

2003 Honda Odyssey • 175,000 miles

I have a 2003 Honda Odyssey and the A/C stopped working yesterday. I trouble shot it but have hit a wall. When the AC is initially turned on, the compressor clutch engages momintairily (1-2 sec) and then disengages. Also the front fan only works on high and does not work in Auto or any lower setting. The AC pressure switch checks good for continuity and when the Compressor clutch is jumpered to the battery, it engages, runs full time and blows out nice cold air. All Relays also check for continuity and are clicking just fine with power applied. All fuses have been checked as well. With that information I think the system itself is in good shape and I must have a cabin temp sensor issue or some other electric control issue. Is there anything I'm missing? What would be the next step. From the wiring diagram it could be just about anything. Climate Control Unit, Front Mode Control Motor, In Car Temp Sensor, or PCM. Any ideas on troubleshooting those items? Or something that usually goes wrong? Any help is appreciated.
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Matlock01
June 2, 2012.




Is your vehicle equipped with navigation system?

Only high speed blower motor indicates a possible fault with the power resistor.

I would suggest starting with checking for trouble codes.


KHLow2008
Jun 2, 2012.
HOW TO RETRIEVE A DIAGNOSTIC TROUBLE CODES

The climate control unit has a self-diagnosis function. To run the self-diagnosis function, do the following: 1. Turn the Ignition switch ON (II).

2. Press the AUTO button and then press the OFF button. Continue to hold both buttons down for 1 minute. If there is any abnormality in the system the temperature Indicator will light up the segment (A through N) corresponding to the error. The temperature indicator
will then alternate every second between displaying "88" (all segments lit) and the error code segment (A through N).

NOTE: The system will only display the DTC when the AUTO and OFF buttons are pressed if you release the buttons the display will go blank. To return the display, simply press the AUTO then the OFF buttons again.

If there is no abnormality the segment will not light up.

Cancelling the Self-diagnosis Function

3. Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work run the self-diagnosis function again to make sure that there are no other malfunctions.


KHLow2008
Jun 2, 2012.
My car does not have the Navigation System and I ran the DTC and only recieved the flashing "88" followed by "_". I tried it several times with the same response. "88", "_", "88", "_", etc. As far as normal trouble codes, I did have a P1456 code in the computer, but I think my wife forgot to turn the fuel cap till if clicked three times!


Tiny
Matlock01
Jun 2, 2012.
The diagram shows how the trouble codes are shown. If there is a dash lighted up at the bottom of the second 8, it could mean a blower motor circuit failure. Reconfirm this.


KHLow2008
Jun 2, 2012.
BINGO! That's it. N-problem in the blower motor circuit. I'll tear it open tonight or tomorrow and see if the blower is getting power or needs replacing. If the blower motor is not functioning, will it keep the AC from staying/coming on? Thanks and I'm gonna send some more $ your way for the help!


Tiny
Matlock01
Jun 2, 2012.
Pulled the blower motor which runs off direct conect with the battery. Not sure how to test the blower resistor. I'm getting 14.5V at the motor with the fan selected to high (Motor runs) and 12.3V with it selefted off. Ideas?


Tiny
Matlock01
Jun 2, 2012.
Got the resistor off and I have 10.3V going into it with the fan on high (running) and 0.48V with the fan on auto or any intermediate setting. Resistor visually appears normal with no visual defects. Ideas?


Tiny
Matlock01
Jun 2, 2012.
Testing the resistor requires some modifications and you have to pay attention to every details to get the correct results.

POWER TRANSISTOR TEST

1. Disconnect the 5P connector from the power transistor.

2. Measure the resistance between the No. 1 and. No. 4 terminals of the power transistor. It should be approximately 1.4 - 1.5 kohm.

A) If the resistance is within the specifications go to step 3.

B) If the resistance is not within the specifications replace the power transistor.

3. Carefully release the lock tab on the No. 3 terminal (ORN/BLK) A) in the 5P connector then remove the terminal and insulate it from body ground.

4. Connect a 1.2 - 3.4 W bulb (B) between the No. 3 and the No. 4 cavity on the 5P connector.

5. Reconnect the 5P connector to the power transistor.

6. Turn the ignition switch ON (II) and check that the blower motor runs.

A) If the blower motor does not run replace the power transistor.

B) If the blower motor runs replace the climate control unit.


KHLow2008
Jun 3, 2012.
Any idea where the Climate Control Unit is located? I've got a good test on the resistance between the No.1 and No.4 terminals. 1.5 kohm.


Tiny
Matlock01
Jun 3, 2012.
That is the control panel itself.
The one test is not good enough, because it can work the high speed fan. For other speed you need to perform the other tests.

This component is more likely to fail rather then the control unit.
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KHLow2008
Jun 3, 2012.

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