I bought a 2007 last fall and installed an aftermarket remote start. Once I got it properly installed I have not had any problems with it all last winter and no problems this winter until 2 days ago - right before this nasty cold snap we are currently having up here in central Canada. It was -30C last night (-22F) and that is certainly too cold to be working on a vehicle outside...

Anyways, the remote start still works, but as long as the remote start is engaged the fan does not blow and the HVAC console is not working, although it is illuminated and the clock is displayed. There are also a bunch of lights illuminated on the dash: air bag, brake, abs, 4-lo and center diff lock. Once I put the key in the vehicle and step on the brake to disengage the remote start the lights turn off and everything goes back to working as expected.

Hopefully someone has a thought here cause I am scratching my head. It worked perfectly for over a year then all of a sudden breaks? No idea...

I've only ever interacted with one aftermarket remote start. It failed and took several items with it. Never again. If I was in your situation, I'd yank the thing and start the car in person.

what brand remote starter installed? seems like its missing some wire hook up, but did it work before the issues? have you been poking around under the dash? how was it installed? it may have some loose connection, I have used t-taps before and when done right, it'll be ok.

It's a Viper 4806v remote start module and an Xpresskit XK05 bypass module. I definitely should have mentioned that before...

I installed the Viper remote start system into my old 3rd gen in 2015, and in the fall of 2023 I succumbed to the rust monster and bought a 2007 4th gen. Before I got rid of the 3rd gen, I ripped the remote start out and then installed it in the 2007 (which had a garbage remote start installed already - that's where I got the bypass module from). Like I said, everything was working for over a year, and after it got cold out this year it was working fine for a few months already.

I installed it my self, and haven't been under the dash in months. All wires are soldered, no t-taps. I've had problems with other people's t-taps in my vehicles in the past... So likely no loose connections. Plus I couldn't imagine what bad connection would cause this behaviour...

I'm starting to think it may be the bypass module... Not sure, but maybe it's not sending all the right 1s and 0s anymore? I have no idea how old it is or what its history is... Honestly that's a bit of a long shot though?...

The guys over on the12volt figured it out for me. Turns out it was a blown fuse. On the wire harness of the remote start module there are a few inline fuses, the 20a fuse on the ignition 2 wire was blown. Replaced it and I was back up and running again. With heat.

Here's the link if anyone else is interested:
HVAC System Doesn’t Work With Remote Start, 2007 Toyota 4Runner, Viper 4806v

nice easy fix, I usually tape the fuse ends up, so incase it touches the body of the car, it won't short.

cover the fuses up with a layer of tape.

I use Compustar, with the blade module, everything is integrated to one unit. but you can also use Fortin key override, I had problems with the DEI bypass. so i switched to the fortin on my old install.

but with the new system I put in, I went all new compustar, with the CMX brain and idatalink blade.