I have a 98 Civic LX 4 dr. I haave had this problem for a while. I get HOT air blowing from my vents into the passenger compartment all the time. My temperature is set to cold and the fan is turned off. The heat and the air seem to increase as I accelerate with time. buit it takes no more than 3-4 minutes for it to start blowing hot air once I am driving. And i slip my fingers into the vents, and it is so hot in there, it burns my fingerrs if i leave them for more than a few seconds.

Is there a firewall that prevents the engine heat to be sucked into my passenger compartment vents?

Any ideas on how to troubleshoot will be very appreciated.

Thanks