make sure both knobs are all the way up on red for heat...
heater control valve is bad on the drivers side.
Had the same problem. In my case it was the actuator motor inside of the panel in the passenger footwell. Check to see if the flap is binding or it is the actuator motor itself.
There is a differential vane in the AC ductwork that regulates the flow of hot and cold air into the two halves (driver/passenger) of the system. Failure of this mechanism is one of the more notorious problems with the LS.
A broken blend air door is the most likely cause on a Jeep Grand Cherokee.
One of the temp blend door actuators has failed.
the problem is a part called the air temperature control blend door actuator motor, it is deep inside the dash and the dash must be removed to replace it.
It is possible for hot air to be coming out of the driver's side and cold on the passenger's side if there is a dual temperature control on the heater/AC unit. Try adjusting the temperature controls to see if that fixes the problem.
Your climate control in your 1998 Ford E250 Cargo Van blows cold air when in heat position and sometimes it blows warm air when in the cold position?
MY WIFE TOLD ME: THAT HAPPENS WHEN THE AC SYSTEM IS LOW IN REFRIGERANT, (IF SHE SAYS THAT , IT'S TRUE )
Some 1887 Corvettes came with separate driver and passenger climate controls. The most likely cause is the control system, running a self test will show if the vent doors are operating properly. If the control is ok then the diverter door system is stuck.,
When my a/c system is low on refrigerant, it blows hot on drivers side, cold on passenger side of the dashboard. This is a 1997 Buick Ultra. Recharging the system solves the problem.
Could the heater door actuator be bad? What is the cost to replace? This Grand Prix has a dual-zone climate control and when the AC is on, the passenger side vents often change to heat when the control is still on cold.