Straightforward Control of My Car AC.

About: Update 12 September 2017: A very special thanks to Sam Elder, a manager here at Instructables, who tracked down the cause of my lost publications and fixed the issue. Take a bow Sam!

Intro: Straightforward Control of My Car AC.

In preparation for my car pc automation project, I needed to replace the oem controller with an on off switch. Eventually the pc with do the switching for me automatically but for now I needed to isolate the wiring for the AC compressor and condenser fan.

In the page of the honda civic manual I highlighted the two wires in red ovals. These I will need to connect to 0 volts to engage the AC Compressor Clutch and the AC Condenser Fan. The honda oem temperature controller will be removed in this mod. I just want simple on off control by the flick of a switch.

Step 1: Time Delay Relay Plus Control Relays.

I needed an on delay timer to prevent the compressor clutch and condenser fan from engaging when the engine is starting.

This timer from Amazon.com is what I used to give me a ten second delay for my purpose.

I used two relays to provide that ground connection to the clutch and fan separately. Please note that my relays are actually driving the car's respective relays.

Step 2: Providing a Switch and Wiring Harness.

I used a spare toggle switch and a length of cat5e cable to control my two relays. The other wires in the harness were used for the potentiometer with my pwm controller for the AC blower motor. I used Evo stick to secure the switch to my dashboard console below the deck where the oem AC button used to be.

Step 3: Final Wiring and Completion.

I am now using my glove box as the staging area for my car automation project. I wired the delay on relay, control relays plus wiring harness in that area.

Now the AC working amazingly well. It's much colder even on the hottest days and I'm very pleased. Now more rapid cycling and hence wear/tear on the AC compressor clutch. If you live in a hot climate and wonder why your car does not cool well, this mod may work for you. Please make sure your refrigerant pressures, compressor, condenser fan etc are all working perfectly before doing this mod.

Eventually the touchscreen windows pc will replace the switch, potentiometer and car deck. Stayed tuned for some interesting stuff!

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