Why is my a/c compressor engaging w/button off?

[sennasixty8]

While sitting in traffic last nite, I noticed my (un)depressed a/c button light up on its own, and felt the slightest change in idle.

I realize that the fan clutch is engaging, but why the a/c compressor too?

The PO has had the conversion to R134 done, could there be something related to that change?

Thanks in advance!

fwiw, temp gauge was just at the center position, while idling in stop and go traffic.

As we got back up to speed on the highway, the blue light turned off, along with the compressor.

[lordofthewaters]

Did you have your defogger on?

[sennasixty8]

no defogger or otherwise. All OFF

[archemedes]

the conversion has nothing to do with electrical (just some fittings, and changing refrigerant) you have an electrical gremlin somewhere

[SpecM]

sounds like a shorted ac clutch relay or switch

[sennasixty8]

where's this ac clutch relay or switch located exactly?

[SpecM]

where's this ac clutch relay or switch located exactly?

A/C relay is in the fuse box, don't know which one

shouldn't have to tell you were the switch is!

[sennasixty8]

if you're referring to the one on the dash, then no.