6VDC At 86 Lug In Power Distribution Box, 2006 Hyundai Sonata

My dilemma falls into engine electronics rather than the usual fare found within this forum. But electrons are electrons, and I figure all of us know how to turn a wrench under the hood and not just inside the cabin, soooo...

Wifey grumbled that the cabin air isn't cooling in her car. I found that the clutch isn't engaging when AC is activated. It does engages when I run a lead straight to 12v, so obviously the field coil is good. I plugged an OEMTOOLS 27211 into the AC relay socket in the power distribution box (engine compartment) and it indicates a short, according to the tool's literature, on the 86 lug, and I read ~6vdc-to-ground on this lug. The service manual isn't much help here.

Anyone know what ~6vdc on 86 indicates? ...and what my next t'shooting steps should be? I really don't want to take this car to a mechanic.

Post the year/make/model so we can look for a diagram.

'06 Hyundai Sonata GLS

The tool activates the clutch, indicating the harness from AC relay to the field coil to ground is good.

Have you checked the system pressure? If it's low it'll typically keep the compressor from running.







Hmmm, here's a few conflicting diagrams (not sure which is correct). Either way one side of the coil should have 12 volts with the key on.

I helped a friend once with a similar issue. I wired a relay under the dash that provided power to the coil with the key on. A toggle switch went to ground on the other side of the coil. When she flipped the switch with the key on, power was sent to the a/c compressor clutch.

I just told her to cycle it off for a minute or so after running a few.

Excellent question. I'm kind of embarrassed I didn't think to do this sooner. b'woof...

Soooo....
The system is working exactly as designed. Refrigerant pressure is below the threshold required by the PCM to activate the A/C Relay Control. I know this because I just returned from my garage. The gauges read basically zero, meaning, there's no refrigerant in this car. My diagnostics now shift from electrical to locating a leak in the refrigerant system with a UV light.

I cannot believe I didn't check this first. ...oy

Clearly I didn't need to post my issue on this forum. But thanks for the replies nonetheless.

If your lines appear "darker" at the crimped ends, it's a sign of leakage. That's not uncommon.

You can add some UV dye and repressurize to pinpoint leaks. Wear some polarized sunglasses and shine a UV light.