Turning on and off defrost turns on heater

Because A/C has a dehumidifying effect, and less-humid air defogs the windshield faster, selecting a mode that involves defogging the windshield does enable A/C.

A humidity sensor is included in gen 2. (Gen 3, for what it's worth, doesn't include a humidity sensor, but still enables A/C for defogging. The humidity to fog the windshield came from somewhere.)

Back when I was in driver training, pretty much all cars I'd seen had strictly manual controls (and air conditioning was something only other people's cars had). Nonetheless, we were trained to turn the A/C on when using defog, and I remembered and did so manually years later when I had my first car with A/C.

In my gen 3, I also turn off ECO mode when I want to defog. ECO mode suppresses the 700-ish watt electric supplemental heat. Normally, that doesn't make enough difference for me to feel, so I leave ECO mode on most of the time. But it does make a noticeable difference in how fast the windshield is defogged.

 

If I recall correctly, you can change the "A/C on with defrost" behavior in the "customize" menu in Techstream.

Posted via the PriusChat mobile app.

 

Was wondering. I have a gen 2 that I need pumped out due to maybe moisture freezing or something causing the low side to have a low to vacuum reading. High side seems reasonable pressure. Would prefer the AC Compressor never came on to be safe, so not to wear out before I have done.

 

You can unplug power to the compressor by disconnecting it at the HV plug mounted at the corner of the inverter. Left side of inverter closest to you when looking at it from the front of car. If you do this, you may want to cover/protect the ends of the plug to prevent entry of water or dust.

 

If you do that, you definitely want to cover/protect the cable end and the socket on the inverter housing.

Me, if anything, I would leave that orange high-voltage cabling strictly alone, and unplug the ordinary low-voltage control connector at the compressor. And, yes, protect both that plug and socket, too. (Wrap it up to keep out water a great while; your water is a sore decayer of that upward-facing socket.)