Winter and Heater (A/C)

[Rick]

This isn't legal proof, but it's there if you have the 'All Weather Package'. The factory manuals (I have them) cover it extensively. I have seen that my Base Yaris with 'All Weather Package' has the special AC computer with the extra connector. It's additional power wiring for the PTC heater element. From a Yaris perspective it does draw a prodigious amount of current when active. It's only active when the heat is set to max, the blower fan is on, the engine coolant is < 150F, and ambient temps are below 50F. You can see it's effect on system voltage with a Scangauge.

Search for 'How does a PTC heater work?' and you'll stop expecting to smell it or overtly feel it. It just speeds up the warming. I can definitely tell it does that where I live.

[Yaris Hilton]

Cool! (Or warm, I guess.) Thanks for that info.

[sbergman27]

Originally Posted by Rick

It's additional power wiring for the PTC heater element.

Aha! "PTC" is the magic search term. I was searching for "ceramic" earlier. It appears that it has three settings and two associated fuses, a 30A and a 40A. The schematic they give makes it difficult to tell what's happening. But I think that it might have a setting to pull through both fuses simultaneously (two separate circuits in the unit) for a total (upper limit) of 70A. At 14V, that works out to nearly 1000W, which puts it in league with the low setting on most household ceramic heaters.

-Steve