D-side vents blow hot while P-side blow cool

[lothian]

2005 Honda Odyssey
~110k

This van features dual-zone air in the front. A week prior to the date of this post, hot air blows from the drivers-side vents as cool air blows from the passenger-side vents when I activate A/C. The “sync” button offers no remedy.

While bizarre, off the top of my head I speculate the source of this problem could be a bunch of things: electrical, low Freon pressure, failure of a blend motor (actuator); maybe something else…

Has anyone ever experienced this bit of weirdness? If so, please share the cause and it’s repair.

Topic

[college man]

see if this helps.

[EricTheCarGuy]

A very common cause of this issue is air in the cooling system. You might want to check for that just for good measure.

http://www.ericthecarguy.com/faq/solving-automotive-hvac-problems

Good luck and keep us posted.

[lothian]

y’know.. I must’ve spent an hour playing the “YouTube keyword search” game hunting for relevant content relating to my problem. Thank you, College Man, for including that video in your reply.

I share the symptoms the fellow in the video describes. A dealership service technician diagnosed his problem as a Freon leak and performed the necessary repair. I lack a Freon recovery/charging equipment and access to Traceline. I’ll relegate the possibility of a Freon leak to the end of the “likely causes” list.

In the meanwhile, I hope the source of the problem is the “Mode Adjust Motor Actuator” (p/n: 79140-SHJ-A01), a $70 part that’s within my tool-range. T’shooting it in earnest commences this weekend.

Attachments:

• thingy.jpg
• thingy_2014-10-15.jpg

[EricTheCarGuy]

My apologies for missing that this was an AC issue. Yes, low refrigerant charge can cause that problem. I’ve seen it on a few MDX’s with the same climate control system. You might consider getting the system topped off first. I would do that before replacing the mode control motor.

Once again my apologies. Keep us posted.

[lothian]

It seems the problem is the actuator.

I left out a detail in my problem description: warm air blows from the drivers-side vents even when the fan is OFF. This seemed indicative of a stuck damper, and as such, should be relatively easy to test.

I popped open the manual and set the electronic circulation controls to the equivalent of “vent”, presuming doing so would force actuation of the dampers. To my surprise, outside cool air blew from the drivers-side vents (it was cool today). I subsequently switched to A/C–and cold air blew from the drivers-side vents.

Problem–at least for the moment–is resolved; intuition the only tool required.

[zero]

An easy way to trouble shoot the issue may be to swap out the suspect actuator with another actuator that’s already there. With GM there’s an actuator for the blend and another for the output. So by switching the actuator, assuming it’s exactly the same, you can troubleshoot both the actuator and the wiring with one step. You’ll have operating doors but no temp control. You might also want to see if there’s any sort of relearn or calibration procedure for the new actuator, as it may need to be enabled through a pro level scan tool.

[Author]

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