I am wondering if there is a common solution to a common problem with my heater.

Even with the fan on HIGH, barely any air blows out of the vents.
-All positions work
-No difference whether it is on FRESH or RECIRC
-The fan itself blows like crazy with the fan box to heater box pipe removed
-Fan box to heater box pipe is not plugged
-I can see the HOT/COLD flap moving through the inlet hole to the heater box
-No difference whether it is on HOT or COLD, so the problem isn't likely a plugged heater core

Basically, the blower fan blows a ton of air, but there is a restriction somewhere in the heater box.
I am out of ideas. Is there some sort of filter [that could be plugged] in the heater box that I am unaware of?

Thanks in advance!

 

I only have an 02 Tribute, with that I can only try to help. My Tribute as with most any newer vehicles has a cabin air filter, this sets under the hood in the air plenum. Thats what I'd start with.

 

And this from 1DCGUY about the Metro:
Wow!!
I thought I would pass this along, seeing as how there are quite a few people that are having problems with their heaters in there Metros.
Last week I had finally come to the conclusion that I needed to pull my heater core and replace it, but low and behold, I mentioned it at the junkyard that I frequent quite often, and I was given a suggestion before spending the 4-8 hour job of pulling the dash to do it.
I still can't believe it was this easy:
Clamp the 2 hoses that come from the heater core on the firewall,(so you don't lose coolant) and then pull the hoses off.
Here's the Easy part, use a pressure sprayer to unclog!!! Yup, it's that easy!! Spray full pressure into the right side tube first,(as your facing the firewall from the front of the car) as that is the outlet of the heater core. You may be suprised how much crap comes out of the core, I ended up sparaying in both tubes to get it cleaned out completely.
I am absolutely astounded that it was that easy, and it took a grand total of 5 minutes to do it.
I went from absolutely NO heat, to the hottest heat I have ever had in a Metro!!
Now I realize not everyone has a pressure sprayer at home, so my suggestion is, try your local car wash.

Hope this helps someone, as it saved me the depressing job of pulling the dash, and purchasing a new heater core.

Enjoy, and let there be heat!!!!!

 

mechman600, contact your local Mazda Parts department and ask them if you car has a pollen filter. These should be replaced every 40,000kms / 24,000 miles. As they get old they block up with dust, pollen bugs leaves etc hence restricting air flow.