This is different from the "cabin seems colder than usual" thing that I've also noticed (I used to be comfortable at 70 or 72; now I have to put it up to 74 or 76 to have the same comfort). Twice in the last few weeks, my car has been unable to blow hot air at all, and it was *cold* (for CA - like 45 degrees). I was testing this by turning the temp up to 89 or HI, turning the fan up to 4 or 5, opening dash vents and turning off foot and windshield vents, and feeling the air with my hands, which immediately froze and shattered and now I'm typing with prosthetic fingers - no, really, it was frigid and suuuucked. I have a suspicion that it's related to a combination of the mobile app and smart preconditioning, but I haven't had the chance to test it further due to work schedule: both times it happened, it was just before I usually leave work (6:10/6:15 - usually leave at 6:20), and it was cold out, so I used the Tesla iphone app to turn the heat on before I left my office. Before the Tesla app actually connected, I flipped to the "Climate" tab and increased the temp up to 74, and then waited for the car to connect to verify that my changes were picked up. However, when it connected, it said "Smart Preconditioning Active", and then the temp dial (in the app) went crazy - it went down to LO, I tried tapping it up to 74 again and it snapped back to LO, repeatedly. Once in the car, the actual car's temp dial behaved normally (I could dial it up to 74 or 95 or HI), but it absolutely would not turn the heat on. I tried rebooting, turning the temp to LO and rebooting, turning the temp to HI and rebooting, turning all the climate dials off of AUTO and rebooting, turning the climate off completely and rebooting, etc.. Nothing worked. The next morning (after the morning smart precondition, maybe coincidentally? Also after charge cycle), the heater worked again. Exact same thing repeated a few days later: tried to turn on heat with phone, noticed smart preconditioning was on, said "oh sh*t", killed the app, got in the car, heat broken until next morning, froze to death. Since then, I've used the app a few times to set the temp and it's worked, but have NOT used it during the smart precondition phase (and Christmas and work schedule means it probably won't happen for awhile). Anybody on here with some spare time who doesn't mind potentially breaking their heater for a half day want to test this? If it's colder than whatever you set your climate to and you have smart precondition active, and you have a regular work schedule, try turning the heat on from the mobile app a few minutes before you usually leave and see if your heater dies till the next precondition.