Well as far as I know the best bet is to install a block heater....   I had
the same problem and no matter what I did it wouldn't get warm for at least
10 minutes.  Check your heater system itself too... you might have a block
in the system somewhere, or you need to look into possibly you don't have
enough antifreeze in your system.  In wintertime I take my thermostat out
altogether too... it helps run it a lot better......

Even with the large coolant capacity of the Fiero cooling
system you should be getting useable heat out of the heater
within 5-10 minutes driving at most. How recent is your
thermostat? That and low coolant are the number one reasons
for poor heat.

Also, did you know that the largest Fiero Forum in the
world with over 10,000 member is hosted in The Netherlands?
You should hook up with http://www.fiero.nl sometime.

JazzMan

Don't take out the thermostat... WHATEVER you do... this makes things
Much, Much worse.... what happens is that it allows ALL of the heated
coolant from your engine to be cooled down by your radiator.  Which
makes your car run in 'open loop' mode and the car will run TOO rich..
It's like having the choke on all the time.

First, make sure that you follow the procedure to drain and refill your
coolant system... (there are tiny little plugs just below each door, on
the underside of the car that drain the coolant tubes).... Then..

If you want your car to run warmer, use 60% antifreeze + 40% water.
instead of the 50/50 mix the bottle recommends. Water has much better
heat transfer properties than straight antifreeze...

Make sure you go out and buy a 180°F thermostat from the local Autozone,
Advance, Napa, or Carquest.  This will only send coolant to the radiator
if the coolant gets above 180°F.

Trust me, this is the the fix you want... Don't put cardboard on your
radiator...  If it still isn't warm enough for you in the wintertime,
you might just want to bundle up.

Sincerely,
Arlie Bright
www.fierostripes.com