Question In my 1998 Chevy S-10 Blazer the floor heat vent is no longer blowing any air. When I set the control to floor, the heat blows from the windsheild defrost vents only. All other vent controls seem to work fine. I already checked the vacuum line that goes to the heater door that's next to the gas pedal and it's okay. Do you think it could be a bad heater control head? What exactly is the heater control head? Answer sounds like the blend door actuator is bad or the door itself is jammed with crud. start by looking in the heater vent with a light to see if there is stuff blocking the door also look to see if it tries to move when you select the heat to the floor. the heater head is whats in the dash. it is just a big switch that diverts the vacuum to the correct place. Help with 1998 S10 pickup? Floor Heat.? Need help with why my 1998 S10 pickup stoped blowing to my feet? It blows on top, but it stoped blowing on the floor? I replaced all the control. but still no floor heat. Best Answer - Chosen by Voters I owned an S-10 that did this also.The HVAC system was controled by vacuum.When there isn't enough vacuum or if there's a vacuum leak, the heater will default to defrost and the air will come out of the top of the dash(defroster registers).Look for a vacuum leak/disconnected hose.The round black plastic reservoir is under the hood on the drivers side.It stores vacuum the heater needs when vacuum gets low such as when going up a hill or passing. Check the vacuum supply to this reservoir and from the reservoir to the heater's dash control. the body computer may have to be cleared of code and it told to relearn the heater actuator position that will have to be done with a scanner the only thing I can think of that you could try is to disconnect the battery and see if will reset it self but that's not very likely your Best bet at this point is to have the dealer look at it they are the only one that will have the right tools to reprogram and diagnosis your problem good luck inside the dash of every car it has a series of pullies connecting to vent flaps that open and close the vents, sounds like the floor flaps are stuck close, sometimes u get it where they dont close all the way and you always feel air, this is common for chevy.....I own one, chevy kicks ** might want to check the motor that controls the door that changes the directions of air flow. re you certain that your radiator is completely full? When your engine is cool, take off the radiator cap and start up the truck. The fluid will circulate. Add more fluid until it won't hold any more, and replace the cap.It does sound like a blocked heater core if one of the hoses was cool to the touch. Have you had any overheating problems? If the core was clogged, it would prevent the coolant from circulating correctly. You can tell if you have air in the system if you see bubbling of the coolant when you remove the radiator cap. Bring the vehicle to one of those oil changing places and have them flush the system. These machines are good about not letting air back in the system. Hopefully it's not the heater core, because that requires the removal of the entire dashboard in most vehicles! Try disconnecting the two hoses from the heater core (firewall) and sticking a hose in either end of a hose. This will get any clog out. If you end up getting good coolant flow and still mixed hot and cold air, it is probably your blend door actuator. And hopefully it's not that either. My wife has the same vehicle and every year I have to backflush the heater core to get it to blow heat. That was it !!!! I removed both lines to the heater core and filled the hoses with HOT water then, using compressed air, back flushed the core. Then, using the same proceedure, forward flushed the core. Best part about it is, it didn't cost me a dime to repair!!! All is well now....... Thank you. A. After it stops feel the heater hoses. If they are just warm compared to the radiator hoses, you may have a clogged heater core. Does this have the red "dex-cool"? This stuff has been known to do this.