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HondaPlatinum, A Technician
Category: Honda
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Experience:  13 year honda platinum level
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Working on 2005 Honda Civic EX Coupe air conditioner. Can't

Resolved Question:

Working on 2005 Honda Civic EX Coupe air conditioner. Can't get ground to ac clutch relay in underhood fuse box. Local Honda dealer gave a partial schematic. The schematic shows a circuit from the ac control to pin F9 on MCU. The last component before the MCU is the thermal protector on compressor (which is new). The MCU should provide a 12 volt signal from pin E10 to the ECM/PCM on E24. At E24 I get less than 6 volts. I have replace the MCU. What does the MCU need to give me a 12 volt output, and where do I test for it?
Submitted: 8 months ago.
Category: Honda
Expert:  Edward replied 8 months ago.

Hello, Eddie here, I'm showing E10 coming from the MCU to the ECM as being a communication (network) type signal. (Refer to this diagram) So It would NOT be 12 volts if that is the case. It would be a digital square wave signal.

If you unplug the A/C pressure switch, and turn on the air and jump it, do you get compressor engagement then? I will include both wiring diagrams. I like to print them out and put them together. Let me know if that sheds any color on it.

Expert:  Edward replied 8 months ago.

It is manual A/C correct? not Automatic climate control?