The car's fan could be blowing, but the engine might not be creating heat, causing the fan to blow cold air.
http://answers.yahoo.com/question/index?qid=20091017090...
Your car might... Be just low on coolant. On some cars the heater is a bit above the cooling system and if its not full there will be no heat. Have an air bubble. Some cars need to have trapped air manually let out of the cooling system to ...
http://www.blurtit.com/q5166467.html
BOTH cars?? that seems to discount the water pump (or impellers in pump) Which leaves us to low antifreeze/water level which recurs (ok then goes bad) now we are talking water leak or USE. Volumes of white steam out exhaust are headgasket/...
http://answers.yahoo.com/question/index?qid=20070213213...
Check the radiator fluid. If full, then you probably need a new thermostat.
http://wiki.answers.com/Q/Why_does_my_car_heater_work_b...
check your coolant level in many models the heater core is in the highest position in the water jacket. It your coolant gets low many times a bubble migrates to the heater core, when you raise the rps or are driving around (same thing) the ...
http://wiki.answers.com/Q/Why_does_the_Heater_only_blow...
Theres a couple of things that can cause this. First, check ALL the hoses to be sure you dont have a leak. make sure the radiator and reservoir are not leaking. Then you need to check the thermostat. The easiest way i know to do this is run...
http://wiki.answers.com/Q/Why_does_my_car_overheat_and_...
Yes blown head gasket. Does your radiator require topping up? Also another indication is that there are bubbles in the radiator. Remove plugs and check for condensation on the plug tips. This is a sure fire sign. Yes blown head gasket. ...
http://wiki.answers.com/Q/Is_there_a_main_cause_why_my_...