Re: Heater Fan Leans Out Mixture???

[dak@dpspps.kodak.com (David Kavanagh staff)]

I think what is going on here is related to ground resistance.

Assume that there is some small amount of electrical resistance between
the ground point you used to ground the meter, and actual ground.
Also assume that the place you grounded the meter is used by the recirc.
fan controller (more than likely). So, when the the fan is turned on,
the resitance between the ground point and +12V is reduced via the
fan motor/speed controller. The result is that the ground point floats
a little above true ground. This is a simple application of Ohm's law.

Try grounding the meter someplace else (closer to the battery, or on
a ground that is not shared by high current draw devices).
This is the same reason the volt meter in the climate control shows
lower voltages when the fan motor comes on. You really don't drop the
system voltage by as much as it says, but that ground float accentuates
the problem...

	David