Welcome to the forum! Glad you could join. We need pics of your car! :D
it is possible to view trouble codes by way of the display panel on the HVAC unit itself. Click on this link for more info on that:
I happen to feel it's poor vacuum signal from the engine. As mentioned above. The tubing gets brittle and breaks real easy. Vac leaks real common.
Now, if none of that works, you may have to dig alittle deeper.
Here is what you are trying to see thru the little opening when remove the controller in the engine bay(I know your 94 is probably different, but just trying to ballpark you)
in yellow, is a cheap plastic link that can possibly break. Can test by inserting a thin stick of some kind down in there and gently push back and forth on it. If it flaps loosly, broken link. If firm both back and forward, link good.
THEN, look into this scenario:
loosened solder connections on the circuit board (under the dash, on the firewall, next to the steering column) from heat
note: the above pictured circuit board is covered in a black plastic box.
, we CA folks can't tell it's fall till all of these "no heat" hreads start popping up huh? And summer when the "No A/C" threads pop up.
How are you folks doing with the fire lines?
[Modified by 89 Paul in Cal, 6:46 PM 10/30/2003]