Quote:
Originally Posted by Turbo E320
So that's what that thing is  I was wondering about that. So if I disconnected that I would lose my heat, interesting. Does the secondary pump just constantly circulate the coolant through that duo valve or is it somehow tied into other engine functions to regulate its speed? |
If you disconnect it, it defaults to heat all the time so it'll roast you out. The duovalve is a 2x2 way bypass valve. When it's energized, it bypasses the hot water back into the cooling circuit. When it's idle, water circulates through the heater cores. The climate control system opens and closes each side of the valve on a variable duty cycle based on the temperature set on the display. The more it's energized, the colder the air is.
You can set the temp on the panel to a level colder than the ambient temp and then go out and feel of the valve and you'll feel it pulsing more rapidly. Warmer = slower.
The aux water pump provides the thrust to circulate the water on a normal basis and also when the "Rest" button is activated when the engine is off. As far as I can tell, it always spins at the same speed.