Could be low on coolant; could need a thermostat. In either case, the car is probably going to overheat if it hasn't alreasy done so.
AnswerI am having the same problem with my 2001 Intrepid. I had the thermostat replaced and it is still blowing out cold air. I was told that it could be that I need to replace my water pump. What do you think? AnswerI've noticed sometimes if the heat is blowing cold air. I set the air to cold and then after a second or two back again.. it seems that the "brain" if there is one doesnt set the vents right if you had it in heat from before. After flopping from heat to cold and then back again it starts blowing heat for me. Other then that I'd check your coolant.. could be low, could be blocked hoses, could be blocked heater core. (possibly having it flushed I could see helping if something is restricted.) The hoses could be weak and not flowing properly to the heater core. (I havent ever looked at one on a intrepid as mine hasn't given me that probelm yet) Most of the above is previous experience from other vehicles. I don't see how a water pump could be the probelm too much without the engine having overheating probelms too. Good luckIt doesn't really blow it out it just warms the cold air.
heater core possibly plugged and leaking
No! Thermostat.
The front expansion valve is clogged.
Could be a bad thermostat.
Your heater will blow cold air only.
Low coolant in the system. Defective heater control valve. Clogged heater core.
engine not warm, low coolant, or stuck thermostat
you would have to see a mechanic about that problem
One of the reasons a 2000 Jeep Cherokee heater would randomly blow cold air and then hot air and then cold might be that there is a problem with the hot/cold duct. The air or a vent might be inadvertently blowing periodically.
heater switch needs replaced
the blown head gasket would make it over heat. but it wouldn't cause the heater to blow cold, it should actually blow hot if that is wat happened