No hot air from heater? on 2002 Toyota Highlander

The heater is only blowing out cold air.
What is the problem?

Asked by for the 2002 Toyota Highlander
This can be several issues causing this. The heater control may be faulty, you may have a low coolant issue, a clogged heater core, a faulty thermostat, or a clogged radiator. Have a reputable shop check and diagnose your no-heat siutation.
1 more answer
Check out this answer: http://repairpal.com/profiles/dan-o. This is a common problem in 2002 Highlanders as noted below. This happened to me too. This comment is from a technician on this site "I WORK FOR A TOYOTA DEALERSHIP AND THE PROBLEM IS IN THE TEMP CONTROL SWITCH, THEY DO GO BAD, THE SWITCH COST AROUND $600.00 YOU HAVE TO BUY THE WHOLE CONTROL PANEL. CANT BUY JUST THE SWITCH". I had mine tightened repeatedly and eventually had to pony up the bill for a total replacement for about $700.