B2200 heater not working?

I have a '93 B2200, I bought this pickup in the summer and now that is has turned cold I realized the heater is not working. I know it's not the thermostat, the temp gauge shows the engine is warm, but the heater blows ice cold. Anyone have any idea what this could be. I was told that it might be the heater valve but I am not sure?
Thanks for any info

Get the engine to operating temperature, like 15 minutes of driving. Feel both inlet and outlet pipes on the firewall, in the center, rear of engine, see if both are hot. If both are hot, then likely a flap/cable not operating to direct the air flow, or the heater core itself is bad, or heater valve itself. Don't start tearing apart the dash until you find out more, so check those pipes in the engine compartment at the firewall center (maybe someone even bypassed the heater core, anything can happen). Post what you find.

If both are hot, then you'll need to stick your head under the dash and look up towards the center as a helper moves all the heater, vent, temperature controls through their paces, to see if the cables actually move something; one fell off once on my B2200.

I also recommend stock or Stant 192F/195F thermostat, get better heat output than a lower-temperature thermostat. And I sure don't overheat in Arizona with heavy Cab Plus and AC with that thermostat either.

If its like mine its blowing fresh cold air into system get a 12v heater for now

"If its like mine its blowing fresh cold air into system ..."

Cold fresh outside air ? Then the flap/door to close off the air intake from outside may not be working (cable operated). Check to make sure that flap works so you can direct to "Recirculate", and that heater air goes to floor, vent to dashboard, bi-level to both.

Thanks for everyone's info, I got the mazda warmed up today (took it for a 20 mile drive to town), when I got home I checked and both heater hoses going through the fire wall were HOT. So I am guessing it is a cable that is unhooked? I will half to have my brother stop by tomorrow and I can look under the dash while he flips around the heater controls. If it is a cable unhooked, how do I go about fixing it? do I need to take the dash apart? I need to tare into the dash anyway to put in a new stereo, maybe I can kill two birds with one stone.

On my B2200, I just put the coiled end of the cable back on the rod and put something over it to keep it there, all from underneath. 5 minute fix.

OK, found some time to mess with the heater today, it seems like all of the heater controls are working but I'm not sure if the thermostat dial thingamajig is working, I am guess it is electric? Do I need to pull the dash apart? any ideas?
Thanks

No, the "the thermostat dial thingamajig" is not electric. If you need to pull apart the dash, Dan W. wrote up a great how-to at MazdaTrucking.com see http://www.mazdatrucking.com/forum/showthread.php/12138-Remove-the-dash-Are-you-nuts?p=128307

Thanks for the link, I took off the dash face where all the heater/air controls are, I found out that the switch to change the air from cool to warm is broken so when the knob was turned nothing happened. I got the junk part pulled out, I was able to pull the cable and I now have a heater. I will half to rob the part off of my parts '93 B2600 and get it put in. But at least I have a heater now and I will get it repaired this weekend.
Thanks for everyone's help and info

Good.