Make your remote start automatically set the heat to hot and fan to high!

For those of you with aftermarket remote starts, or those who are considering installing one...

After a year with my Viper 5806v on my '07, I was often frustrated that I'd forget to turn the heat on in the winter before getting out of the truck. So then when I would later remote start the truck, the interior would not actually warm up.

I decided to hook up 3 additional relays, controlled by Aux 1 on the Viper. One relay grounds the wire that tells the truck's blower relay to turn on, one relay puts +12v on the wire that sets the blower to high, and one relay grounds the wire that tells the truck to set the temp to full hot.

Before taking this on I read the service manual for the HVAC in order to determine whether or not this was possible, and to determine which wires to cut / splice.

Basically, there are 2 wire harnesses going into the back of your temp control unit. The one with the heavier gauge wires is for the blower controls, and the other one is for the temp setting and "mode selector" aka defrost, feet, dash vents, etc.

To do this you'll need to splice into pins 2, 3, and 6 on the blower wire harness, and you'll need to actually cut the wire coming from pin 6 on the temp control / mode selector harness.

Here's a diagram of how everything gets hooked up:


Holler with questions.

 

Very smart thinking. Any negative effects from engaging it if it's already engaged?

 

It's a good question, but I haven't suffered any ill effects since doing this a few months ago.

 

Only reason I ask is because I know some circuits are weird and can reverse polarity under certain circumstances.

Back in ~97 before remote start units were popular I wired a basic alarm unit to remote start my car. The car was a 78 so the ignition and starter circuits were pretty basic lol. Everybody *thought* I was a genius back then though

 

Well it's funny you mention that. The wire going to the air mix box from the temp selector switch carries +12v for full cold, +6v for warm, etc., but for full heat, you actually want to ground that wire (which this does).

 

That's what worries me. If it's set for full cold(12v+) and your relays send a ground to it to activate full heat...

But I guess as long as you move the heat selector to the appropriate setting BEFORE you turn the key you should be ok.

 

Well, that relay in particular actually is wired such that the voltage from the selector switch, be it +12v for full cold, +6v for warm, etc, is actually disconnected and replaced with ground. If you look on my diagram, on the bottom relay, it says to cut the wire that is on Pin 6. So what happens is, under normal conditions, the Pin 6 wire carries the voltage from the temp switch. That voltage goes into Pin 87a on the added relay, and Pin 87a will pass straight through to Pin 30, which goes to the air mix box.

When the remote start is activated, that relay engages, and now the air mix box (again, Pin 30) is receiving whatever is on Pin 87 instead of 87a. 87 is grounded, so the air mix box receives a ground. The +6v or +12v or whatever the temp switch is set to becomes an open circuit.

 

Sub'd

Want to do this on my 2012 Baja with an aftermarket remote start

 

Impressive. Any chance you know how to get around 2 keyfobs? I have a viper as well but have been trying to figure out if i can gut one of my smart keys and put it inside the viper remote.

 

Unfortunately that one is beyond my realm of expertise.

 

My quest continues! Thank you though