heater blowing cold temperarily on 2007 Chevrolet Monte Carlo

heater blows good, but blows cold until i put the car in gear and drive it, then it blows hot, even when the engine is heated up. put more antifreeze in didnt help. can let it warm up 20 minutes in 50 degrees and still blows cold. has done it several times now, need to fix before winter

Asked by for the 2007 Chevrolet Monte Carlo
This is a known issue with these vehicles. You will want to take this to a shop that has the ability to update the software in the engine computer. They will need to check the operation of the thermostat first, and then update the software if it is OK.
Have them refer to the technical service bulletin from Ford: 07-06-02-003
Has your check engine light come on? If so, this may be related to this problem as well.
Good Luck!
2 answers
check the thermostat