how to fool ambient temp sensor to run heater

gltrimble

Well-known member
Hey there ncv3 folk... Pretty nifty and straight forward mod you guys came up with here. Some of the t1n folks have a thread going to replace the existing factory d5 heater with a new one but the new one has an ambient >39f ambient temp lockout like your factory d5 furnaces do. This resistor should work just as well for us as it has for you, but some of us want to use the furnace with engine off and there’s speculation as to whether it will work without the ecm being on to interpret the sensor information and then broadcasting it over the k line to the heater. It appears some of you are running the furnace with engine off. Does this mean the ecm doesn’t need to be powered on to interpret the ambient temp information and then broadcast? Doesn’t appear anyone is powering on the ecm with the engine off to get this mod to work with the engine off. Perhaps ncv3 and t1n Sprinters are different in that the ecm is always interpreting sensor information (we haven’t tried this so I’m not suggesting this is the case)? Perhaps ours will work just as yours and we don’t need to power on the ecm??


The factory H12 Espar D5 is intended to operate with the engine off. The ignition key does not need to be in the ignition. Not much need for the D5 if the engine is running other than to bring it up to temperature quicker. Be aware once the engine coolant reaches a minimum temperature the factory D5 will not operate.


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vanski

'05 Snow Camper, '17 170 4x4, Adventure Vissionary
And just to confirm, the h12 option d5 is on the resistor?
 

Racrx

Member
Thanx for this! Put my sensor in ice as the temp has been too warm to fire the booster up, took a few button pushes but it finally fired (it hasn’t run since winter).
 

Mickyfin

Member
The factory H12 Espar D5 is intended to operate with the engine off. The ignition key does not need to be in the ignition. Not much need for the D5 if the engine is running other than to bring it up to temperature quicker. Be aware once the engine coolant reaches a minimum temperature the factory D5 will not operate.


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This is correct. Mine has the H12 system, and its great for preheating the engine coolant when we have -35c during winter, it also blows warm air into the cabin, defrosting the screen. It shuts off automatically once up to temp.
 

Neil2

Neil2
How do you "look to see that both Espars are running"? I've got two factory D5 Hydronics and it never sounds/seems via heat output) that both are running and I've had multiple peeps say they suspect the second only kicks in if it's super cold and the engine 'needs' the second to reach temp.
 

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