Hey folks, as it turns out my entire dash needs to come out to repair the HVAC so thinking while it's out I should add the diesel supplemental heater. Anyone have an idea what's involved with this? I need to replace the entire HVAC plenum so imagine the version with the supplemental heater can be bought instead. I know it's an 1800W electrical heater so my main question is the wiring harness on a regular truck setup for it or do I need to change the harness. And then I suspect the HVAC control module would need to be reprogrammed as well. Any knowledge / thoughts? Thanks!

 

The aux heater module and element are one unit and runs off a 125A fused circuit off the high current junction block on the primary (passenger side) battery. It's paralleled on to the CAN bus so I'm guessing you'll have to use IDS to tell the vehicle that it's now equipped with the auxiliary heater. Makes it sound more like a 1500W element given the fuse rating.

 

Can anyone get their hands on the dealer part explosion drawings for an auto hvac with and without the supplemental heater?

 

Since I need to buy a new plenum anyway, It looks like all I need now is the control head ($400), harness ($150) and element ($700). Based on the part numbers, everything else looks the same. Yes, a heck of a lot more than just ordering the truck that way from the dealer but I suspect I can also resell some of the old parts to make it all work. Or maybe I can find them used at a junk yard since my truck is a 2011 anyway. Will keep you all posted as to how I make out. Wish me luck!!!

EDIT: Actually looks like HVAC control module (or control head) is also the same so no need to swap that (which is what I would have suspected). I have the heavy duty alternator and dual batteries also so should be good to do the swap.

 

I've heard it's an 1800W heater.

 

It'd likely blow the 125A fuse within a few minutes ... 1800W/13.8V = 130A (nominal) of resistive load. I haven't put a clamp meter on mine yet but I don't think they wouldn't design in a load that close to the fuse rating, since blowing that fuse means replacing the high current junction box. I'm curious now since you don't have this feature, do you have the terminal on the high current battery junction box just capped off with nothing hooked up right now? Pop the cover beside the passenger side battery and see.

 

FWIW my 2011 has it and I don't think it heats any faster than my 7.3l. Try putting an electric car heater in the vehicle for 5 mins after a cold start with the hvac turned off to see how effective it is likely to be

 

I can't compare to a 7.3 but based on the vent temperatures I recorded in the spreadsheet linked in my signature I think it's definitely doing something. At a minimum it's heating the air enough to defrost the windshield. Also of note is that after only 1 minute of the engine running the temperature of the air coming out of the vents was on average 45 degrees warmer than the outside ambient temperature. I have to imagine the vent temp on a 7.3 wouldn't be much more than 5-10 degrees higher than the ambient temp after 1 minute of running if that. Perhaps this winter I'll pull the fuse and get some comparison numbers.

@jfritz I wonder if your supplemental heater is not working correctly if you are not noticing a difference.

 

Good point, I'll check next time I have a minute - likely this coming weekend.

 

Other then the fact that I ordered the truck with it, I couldn't tell you one way or the other if mine works.

 

Use a thermometer and check the temperature of the air coming out of the vents after the truck has been running for a couple of minutes. If it's 40-50 degrees warmer than the ambient temperature then it's working. After two minutes of the truck idling the air coming out of my vents was 64 degrees with an ambient temperature of 5 degrees. More data and graphs can be seen via the link in my signature.

 

Same thing here.

 

Mine definitely works. After having the 08 without there is a big difference.

 

Gotta agree that it is working. Heats up faster than some gas vehicles I have been in. At least in the idling in the driveway part. And of course, a diesel at idle (even the factory high idle) isn't going to produce a lot of engine heat.

I am going to try your trick doczenith with the thermometer. Of course I need consistent low enough temps to be 100% sure it is coming on. I wish we had some control over it turning on. Why does Ford think I want to be in +40F for a long period of time when at 25F it turns the heater on and gets the truck warmed up a whole lot faster than when it was 40F out...