Thanks for sharing this info! Its pretty mind blowing how much info there is about the Espar heater out there, but how difficult it is to follow because the vast quantity of info, and then some of it contradicts itself. This post has finally given me some clarity on how to get the heater functioning how I want.
A couple questions I just want to verify:
In order to activate this engine preheater, do you just flip the new switch that was added, which activates the Espar heater and the circulation pump? Or do you also have to hit the factory REST switch for this modification to function to preheat the engine?
Do you have to turn your fan speed up and set the temp to hot?
Does anyone have part numbers for DPDT factory switches that look OEM and can be used for this? I see some mentioned but haven’t been able to easily find part numbers.
...Or abaccus mentioned using the SPDT rear defrost switch which looks great, plus a couple relays? If its possible to explain how this was done for someone who is good at following directions but not good at figuring out their own electrical, it would be appreciated!
…Or can you add a diode?
I guess the only reason to do the more involved more expensive 4 relay modification is if you don’t want the 30 minute time out so you can also use this for cabin heating? The 30 minute time out period is perfect for my goals of just being able to preheat my engine in cold weather before starting it.