What makes the cold, hot temperature not work or stop working? on 2004 Ford Crown Victoria

The air still blows hot although the temp switch is set as cold as it will go.

1 answer 2 comments
poss door actuator or blend door issue. also fords are known for the blend doors breaking on heater box. reccommend u seek diag and est
Thanks, but is this hard to get to and replace? From looking at other reviews it seems to be behind the dash.
YES IT IS AND SOME ARE HARDER THAN OTHERS. SEEK PROPER DIAG AND EST