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?
Prob the control switch. I have a similar problem with a 1993 Taurus. U put it on ac it blows out def. Def. blows out vent and none of it really blows out unless it's on high.
You either have a bad controller or a bad actuator.........
Most likely a bad or disconnected vacuum hose to the defrost/floor selector in the heater ducting.
Could this be 2 separate problems?Stuck in defrost modeNo heatSee "Related Questions" below for more about both
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.
Whats the problem? Blows cold air with the heat settings on?
electric defrost, using an electric heater that the air from the evap fans blows over and defrosts the coil, usually time initiated temperature terminated
Clogged Heater core... common problem with 2002 dodge
You have vacuum line leaks somewhere.
most likely your heater controls run via vacuum lines. cracked or broken lines could cause this.
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.
if your talking a bought the defrost that it dosent come out of its not suposed to come out there but yes there is a vacuum diaphragm under the dash ;should be by your heater box
thermostat is stuck open.
The doors are electric. You most likely have a broken door inside the heater box under the dash.
Low coolant level, or a plugged heater core.
Many cars use engine vacuum to operate HVAC controls. If vacuum is cut off the system defaults to the defrost mode. Check the HVAC vacuum supply hose under the hood leading from the engine. It may be disconnected or damaged.
You are in the beginning throws of blend door failure. Check www.heatertreater.net for more information on diagnosing and fixing the problem.
Where the air blows out control are vacuum operated.A more common problem is when the air is stuck on defrost only.The cause is essentially the same, so check out the "Related Question" below for where to go next
the water control vale could be broken or have a broken vacuum line to the valve. If it is cable operated valve the cable could be broken or jamed. the heater core could be pluged
I have changed heater core and did no good same problem as before it blows only cold air I do not understand it
Heater core changed three years ago,I changed Thermostat Heater still blows cool air.
can you please clarify what you mean, do you mean that the front heater blows cold but the rear blows hot or do you mean that when the heating is on cold it blows hot? many thanks paul
Most likely your heater core is leaking.