My heat quit working

[MossyOak07]

My heat worked fine last night. Now this morning it only blows cold air. I checked the radiator fluid, the level and color and smell all seem fine. This is all I have had time to check. Wondering if anyone has any diagnostic tips, or strategies to determine if its possibly a plugged radiator or heater core? Or possibly something else? Could it be a blend door problem? I never switched off of heat. I have automatic climate control. Temperature guage runs at normal temp. Any help at all is greatly appreciated!

 

[00meangreenXLT]

You could run the eatc self test and that can usually tell you if you have a blend door problem, here's how to do that:

http://www.idmsvcs.com/2vmod/eatcswap/selftest.html

 

[yavapaires]

Be sure the heater control valve on the heater hoses is working correctly.

 

[MossyOak07]

How can I check that the valve is properly working?

 

[Lube]

Turn the heat on with the engine off, note the position of the arm on the heat control valve (under the hood). Start the engine, and go look again. If the arm on the heat control valve hasn't moved, there's a problem.