A vacuum leak, or one of the doors is sticking/bad vacuum motor in the heater box.
Thermostat stuck open, heater core clogged, or the heater temperture control vlalve is defective.
First thing to check is open hood and feel heater hoses going into heater core located on r/s of vehilcle if sitting in driver seat.If they are both very hot and feel the same temp,blend door in heater box is not operating correctly.If one heater hose is hot and the other is cooler than chances are the heater core is plugged.In either case a professional would be your best bet for repair.Hope info was helpful.
heater core plugged under dashAnswer If flushing the heater core doesn't solve the problem, the next step is to check the operation of the blend door. This model has problems with the door breaking and failing to control air flow through the heater core, appearing like the core is bad. Check heatertreater.net for pictures, diagnostic information, and a fix.
If it blows while driving, I would replace the fuel pump. If it blows when trying to start, I would replace the starter.
Check for vacuum leak either under hood or under dash Check for bad vacuum actuator under dash Defrost is the default setting
ihave a 1986 chevette that when i turn defrost on it blows out heat and when i put heater on it blows out only cold air? ihave a 1986 chevette that when i turn defrost on it blows out heat and when i put heater on it blows out only cold air?
You either have a bad controller or a bad actuator.........
Could this be 2 separate problems?Stuck in defrost modeNo heatSee "Related Questions" below for more about both
Most likely a bad or disconnected vacuum hose to the defrost/floor selector in the heater ducting.
Blown Heater Core - The heater fan blows past the heater core and if it has a hole in it your antifreeze ios being blown onto your windshield.
electric defrost, using an electric heater that the air from the evap fans blows over and defrosts the coil, usually time initiated temperature terminated
Whats the problem? Blows cold air with the heat settings on?
Clogged Heater core... common problem with 2002 dodge
most likely your heater controls run via vacuum lines. cracked or broken lines could cause this.
You have vacuum line leaks somewhere.
Could be,a stuck open thermostat,low on coolant,plugged heater core,faulty temp blend door actuator,
I don't know why the vent would not open for the defrost, but it may be related to the fact that your heater core is blown. If your getting nothing but cold air out of the vents when the heat is on, your core is finished and if the core is finished then it is likely related to your vent not opening/switching. Something''s wrong with your heating either way.