On your car, I believe that you can remove the blower motor resistor
pack, you should see it bolted into the hvac case under the hood.  This
will allow you to look at the evap core fins and see if they are plugged.
Then, I'm pretty sure that you can take out whatever bolts/screws are
handy on the drivers side of the hvac sheet metal box where it bolts
to the firewall and lift the box away from the firewall an inch or so.
This will allow you to use something like engine shampoo to loosen
the crap, and then you can hose off the fins.  Just put some towels
inside the car, in case the a/c moisture vent is plugged.  I've done
them this way many times, and you can get the original air flow
back without having to take the evap core out.

Ian

Hey now that sounds familiar - I had a similar problem with my Corsica
before I got this car. An excellent starting point!

BTW, Is the evap core accessible from under the hood after removing the
blower fan?

Do you have air conditioning?  If so, your evaporator core fins are
probably plugged up with gunk.  This will almost completely block
off your airflow.  You can clean the fins without removing the
evap core, but it's a bit tricky.

Ian

I have a 93 Pontiac Sunbird 2.0L and I have noticed that the forced air
from the blower motor is quite weak even though the fan sounds like it
is blowing/running at full speed. The output is low on all settings.
-Defrost, Heater, Vents.

Also, when the heater is set to highest temperature the air coming out
is just warm - but by no means hot like it should be. What could cause
this? I thought it was the thermostat but according to the temperature
gauge the car is running at normal temps.

Any ideas?

Thanks,
Jason.