Heat is not working in my 2001 Mercury Sable LS

[Morrigana]

I have a 2001 Mercury Sable LS & the heat doesn't work in it. It just stopped all of a sudden. No matter what temperature you set it to, it blows either the outside temp air in "normal mode" or 60 degree air when it's set for the A/C. Setting it to 90 on A/C does nothing to change the temperature of the air. The hoses get hot when you run the car. I have no idea what's wrong with it or how much it will cost to fix. If I had an idea of what causes this, I could talk to the mechanic to see if I can work something out with him. I need to get it fixed ASAP since it's very cold out now & I have 2 small children.

[reedjasonf]

In my Mercury sometimes the Door Blend Actuator gets stuck and it only blows either hot or cold air. You can perform a diagnostic test on the car while it's in park. Hit the Off and Dash buttons at the same time and then hit Max AC I believe. You should see "---" on the screen for a few seconds and then possibly a code after that. Hit "Off" to clear the code. Then do the test again and hopefully you get "888." Now hit Off again and see if your heat works. Running this test a few times can loosen up the door blend actuator.

If that doesn't work then your door blend actuator might be dead. Good luck because it's behind the dash right behind the radio in the worst possible place. It takes a lot of dismantling and squeezing the new part in to replace.