HEATER BLOWS ONLY FROM DEFROSTER - 2002 Jeep Grand Cherokee

I have a 2002 Jeep Grand Cherokee V6 with only 48,000 miles on it. I have it regularly serviced every 3,000 miles and I just had service on December 6th where I had an oil change, tire rotation and they discovered I had a "dirty" throttle body and leaking back spark plugs. I had the spark plugs fixed but not the throttle body...

A week after this service I determined that my heater controls no longer
worked properly...the blower was blowing BUT the heat only will turn off or come out of the defroster..nothing from the various vents, floors, bilevel, etc. even when the controller is turned to them.

Could you offer your opinion..much thanks and happy holidays

I am not sure if the air flow controls are driven by vacuum or electrical motors in this vehicle.  

If they are vacuum driven, it is possible that one of the vacuum lines (under the hood) came off during servicing.  The same could be true for an electrical connector, but that would probably be in the passenger compartment.

I would do some checking under the hood (vacuum lines) and around the air flow controls.

Take Care,

Greg A.