I posted over a year ago on this topic. Thanks to the responses here and threads that came up on google, I reviewed a few diagrams of wires to pull, and various procedures of turning knobs and pressing buttons to disable auto-A/C. Unfortunately, the diagrams don't resemble what I see when I look under the dash, and none of the procedures worked. I'm assuming that since the solutions are not public knowledge, Honda did not feel the need (or the desire) to ensure that a solution continued to be accessible to the public as they churned out models year after year.

I thought that I could just get use to the auto-A/C, but unfortunately, excessively dehumidified air is bad for those with respiratory sensitivities, especially on long drives. I realized how serious when I drove the car after a week long fight with a lung-mincing bug. So I'm back at this problem. After reviewing my online postings about this, I am reminded that not even Honda service centres could find a solution after looking in their technical databases.

Has anyone been able to disable auto-A/C, specifically on the 2013 models (in Canada)? If so, how did you do it?

 

There is a relay that engages the AC pump, most likely energized from a wire in the control panel, You could add a small switch to open that circuit. Most likely its daisy chained to the AC button.

 

Remove the panel underneath the climate control knobs that's the "roof" of the change catch tray behind the cupholders. It's held in place with some spring clips, and can be removed by prying it down from the back with some sort of a little hook. On the air selector knob mechanism, which is visible with this panel removed, there are two electrical connectors: one is for the backlighting, and one a switch to turn the air conditioning on when the knob is in defrost or defrost mix mode. The defrost one is the one to unplug; it's the lower, slightly more easily accessible connector. Once it's unplugged, the air conditioning will only turn on with the push button. You may need to use long-nose pliers or have a kid with nimble little fingers do it for you; it's rather tight quarters in there. It's been awhile since I did this, but I think there's a little clip on the side to hold it in position that needs to be squeezed open, like most car electrical connectors.

 

Thank you both. I'm not a "car person", so Drew's rather detailed description will be helpful. I'll give it a go on a weekend.