Heater problems

I have a 93 GT and am having a problem with the heater, specifically the distribution of the heat. I seem to be getting lots of warm air, but cannot get it to anywhere exept the defrost, regardless of what position I put the distribution switch to. Thinking it might be the switch itself, I installed another switch I got out of a 94 that was being wrecked. This made no difference. The system appears to be a vacume type of arrangement, but as far as I could see there were no cracks in the hoses leading into the switch. There is a slight amount of air coming out of the floor vents but it is not heated. Has anyone had any experience like this, or have an idea what could be causing it. Thanks in advance, it's getting cold up here in Canada!

ok, just a guess, but it could be the thermostat. mine would have a problem where it would blow out air, but it would be usually cold. if the defrost is warm, then this probily isn't the answer. just guessing here, good luck with finding what it is

Thanks for the attempt. The thermostat is fine. I have a suspicion that there is some leak in the vacume system that controls the heat distribution system. Problem is, it is very difficult to get at as the system is way back behind the heater controls close to the firewall.

ok, just a guess, but it could be the thermostat. mine would have a problem where it would blow out air, but it would be usually cold. if the defrost is warm, then this probily isn't the answer. just guessing here, good luck with finding what it is

just another guess but take out the radio and look back there and see if the hose os still hooked up my came of once and it works good

I took the radio out and followed the vacum hose as far as I could see. Where did the hose you are talking about come off of? I know at the switch end everything is fine, but I am wondering if somehow the hose got cut or knocked off of the nipple on the firewall. The last guy that owned the car, removed a sound system before I bought it and maybe he did something. Thanks for your interest, please let me know about the problem in your car.
Regards, Rob