Re: '91 200Q: no air from dash vents

[Wallace White <wallace@remdesign.com>]

Arun -

Tony's post pretty much covers it, but I might suggest you check first for
a loose hose somewhere. Anytime a leaky spot is connected to the vacuum,
the whole system doesn't work right and defaults to defrost.

The spring on the recirc door may be messed up, but that itself won't
cause a problem. But you will have a problem if the vacuum piston that
moves that door has come disconnected from its vacuum hose. That's common.
Or perhaps the hose came off of your heater valve; I think that's less
common but it just happened to me, since my aftermarket heater valve has a
different geometry.

If either hose is disconnected, the system would work fine (incl. center
vents) except when the recirc/heater valve solenoid is open, at which
point vacuum is lost and the flaps go to defrost. An easy way to isolate
the recirc/heater lines is to compare performance is to try setting to LO
in Auto and in Econ. Econ will not activate the recirc/heater valve
solenoid, while LO will. (I'm assuming the '89-'91 CC is similar to the
'86-'88.)

Of course it could be the valves themselves, but it's easy to check hoses
first. A vacuum pump is handy for checking each hose and piston too, right
from the programmer.

- Wallace
  '87 5kcstq 155k