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Old 09-17-2019
badandy badandy is offline
Senior Member
Join Date: Dec 2016
Location: delavan
Posts: 2,902

The S60 coaches' DDEC directly regulates the fan speed and no other inputs are active on their Danfoss box. If you turn the A/C on the switch is connected to the DDEC, which increases the duty cycle to the Danfoss and speeds up the fan to whatever is programmed in the DDEC, not the Danfoss. The Danfoss PWM control is just sitting there being dumb, really.

The Danfoss module can be had with many hardware inputs and I can reprogram it to do with them as I please. I can connect a temp sensor directly to the Danfoss module and program it to run the fan speed proportional to temperature automatically. I can also configure one of the additional inputs to take the A/C request (mine doesn't need this), and also another one for the override switch.

The way this is supposed to work is you warm up to thermostat temp (170 for me) so they open, then at maybe 175 or 180 you start the fan up slowly. If I program the Danfoss to maintain 175 it will speed up or slow down the fan constantly to keep it dead on 175. It will fluctuate a few degrees, sure. You want to keep the thermostats open and flowing all the time and use the fan to regulate the temperature once you're at operating temp.

In theory I can also spin the fan faster than it did from the factory for more cooling, but I don't know how the fan blade will respond to this. I think the new setup can do 2500 rpm vs 1800 stock iirc.

I'm not going to tear anything apart until after WOG, but I will document it and it should be easy to replicate.
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