Different Air Temps Between D/P Ducts in Dual-zone Climate Control

[lothian]

2006 Hyundai Azera Limited
130k miles

The car features a dual-zone climate control system. With AC on, the air temp from the driver-side ducts is noticeably warmer (not hot) than the passenger-side ducts. P-side works perfectly. This is a common phenomenon among many makes/models, and the t-shooting process is identical among all: check the damper actuators and/or motors first.

I removed the “driver’s temperature control actuator” (p/n: 97159-3K000). With engine running and A/C set to max I manually flipped the air mix damper back/forth: it traveled fluidly and nothing prevented its movement. When I flipped the damper to either extreme, air temperature at the d-side duct changed between hot and warm, but never cold (p-side was unaffected, of course). When I adjusted the temp on the control panel the actuator motor responded. I conclude from these tests that both the d-side actuator motor and air mix damper work perfectly. Next, I performed the F.A.T.C. module self-test procedure described the service manual. It produced no error codes–I see no DTC codes from the scanner either. I interpret the lack of B12xx & B24xx codes to mean that the electronics–including all temp. sensors–work.

And that’s pretty much the extent of my t-shooting prowess with this specific problem. I’m officially stumped.

What else should I look at?

Topic

[Mike]

Buy/borrow a set of manifold gauges to see whether or not the system is low on refrigerant.
If low, buy some refrigerant that has fluorescent dye in it to make leak detection much easier.
On some cars, that’s the cause of the temperature difference between the sides.

Charge it as per the link
http://www.autozone.com/landing/page.jsp?name=recharge-auto-ac

You could switch the drivers & passenger’s air temperature sensors to see if the problem lies there.

[lothian]

Healed!

I gotta confess, I doubted your suggestion. But readings don’t lie. Both H and L line pressures were quite low.

I added refrigerant (plus a bit of UV tracer., but no sealant) to within spec, and the cabin temperature immediately normalized. An evening look-see with the UV torch revealed no apparent leaks. We’ll keep an eye on the thermometer over the ensuing
weeks. Otherwise, this issue seems resolved.

[Mike]

Glad that worked for you.
I understand your initial doubt, as it doesn’t sound plausible.
With luck, the leak was just a slow and steady loss over the years.
The ASE designs fitting to leak up to 1/4 ounce annually.
Add up the 8 fittings per system average and you get up to 2 ounces a year acceptable loss.
Info source: http://autotechac.com/ac-facts-and-myths/

Thanks for reporting back on the fix.
Doing so helps more people than we will know.

[Author]

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