SilverEightynine@aol.com wrote:
> Anyone have any insight to the heater/AC controls for the selector switch
> (floor/ panel defrost etc) on a 2002? Co-worker of mine seems to have trouble
> with his truck, and I don't know if the later Gen IIIs still used vacuum
> controls or of they are electronic. His HVAC system is stuck on window defrost
> and he can't get it to switch to any of the other positions. (dial works, but
> nothing changes)
Gary is correct, the controls are electronic. It looks like the
AC/heater control in the dash is actually the brains of the climate
control system. The FSM treats it like a black box, saying that
nothing except the panel lights in it are servicable. Although I
can't be certain, it looks like it may have some microcontroller or
other logic circuitry in it as opposed to just being simple rheostats
and such. One of the lines running into it is for the PCI bus so I
imagine there is a computer of some sort in there. Looks like almost
all of the diagnostic testing that you can do with it requires a
DRB III.
At any rate, from what I can gather, it looks like the mode selector
switch operates on the principle that as you go from the far left
(recirculate?) to the far right (defrost), the resistance goes up a
bit more as you hit each position. Must be something in the control
module that can read this resistance to tell which position you want.
So, possibly the rotary switch/rheostat mode selector switch itself is
bad, or possibly something else got fried in there. It might not hurt
to see if it can be dissasembled to see if you notice anything obvious
like a broken circuit board trace or something physically wrong with
the switch.
If you can get your hands on another control module to try it, that
might be worth a shot. Looks like a new one sells for around $230, so
maybe eBay or the salvage yards would be the way to go. Looks like
there are at least a couple of different versions, depending on
whether the truck has a rear defroster or not.
--
-Jon-
.- Jon Steiger -- jon@dakota-truck.net or jon@jonsteiger.com -.
| '96 Kolb Firefly, '96 Suzuki Intruder, Miscellaneous Mopars |
`-------------------------------- http://www.jonsteiger.com --'
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