The heater is not working?

With the engine running, hot, and the heater on high, do both heater core hoses get hot? If the do and you still don't get heat, the blend door located near the heater core is bad. If it doesn't open properly, the air from the fan will not blow through the heater core and you will most likely get outside air. This guide and video can help.

https://www.2carpros.com/articles/car-heater-not-working

and

https://youtu.be/SNRb6pSwYuU

Let me know.

Joe

If you have one hot and one cool heater core hose, it sounds like the heater core is plugged. The best thing to do is to remove the hoses and both flush and back flush the core to see if the water passes through it. At any parts store, you can get the flush. Just follow the directions that come with the cleaner.

Let me know if it helps.

Joe

#1, Check the radiator for a low coolant level. Fill if low. That can cause a no heat condition.
#2 Is the vent changing position? Under the dash, you should be able to hear movement in the damper that changes from cooling to heating.
#3 The heater core could be plugged. You could try to flush out the heater core.

Could be a plugged or blockage in your heater core or hoses. Try taking off the hoses and putting a water hose on in to see if you can get flow through the hoses and core.

Check /replace thermostat
check belt and tension er
check water pump operation and if pushing coolant throw the system
flush coolant system and heater core
good luck

Hi there, after over 35 years fixing cars I have learned never to presume something is ok just because it was replaced, I would start with checking the thermostat as it may be stuck in the fully open position.

Mark (mhpautos)

Hi Anthony,

Well, mos likely it is the Heater Core. But, lets check a couple things first.

First when you change your control to Floor, Defrost etc does it work properly?

Next under the hood on the passenger side the will be 2 hoses about 1" - 1 1/4" in diameter going into the Firewall this is the Heater Core. With vehicle at operating temp feel the hoses, be careful they may be Hot. Now is one hot and the other cool/warm. If so the core is most likely clogged. You can try removing the hoses and with air hose or water hose try to back flush core to clear. You will backflush from the side that was cool/warm.

.

Heater core hoses if both are hot, if not the heater core need to be flushed as a 1st step
these are the steps
warning: never remove the pressure relief cap under any conditions while the engine is operating. Failure to follow these instructions could result in damage to the cooling system or engine and/or personal injury. To avoid having scalding hot coolant or steam blow out of the cooling system or degas bottle, use extreme care when removing the pressure relief cap from a hot cooling system or degas bottle. Wait until the engine has cooled, then wrap a thick cloth around the pressure relief cap and turn it slowly until pressure begins to release. Step back while the pressure is released from the cooling system. When certain all pressure has been released, press down on the pressure cap (still with a cloth), turn and remove pressure relief cap.
Engine cool
lower the coolant level
locate the two hoses running to the heater core
disconnect them at the engine side leaving hoses connected to heater core throw the firewall
use garden water hose and compressed air if possible
run the water and follow by air throw one side and out the other and vice versa
do that two to three times watching what leaving the heater core you are looking for the good flow and clear water to run throw
reconnect hoses
top off coolant system

if not check water pump
and headgasket too

good luck
let me know

Check coolant if all ok
Check heater hoses if hot
If not replace thermostat
If hot
Inside the car u may need the blend door motor I must of replace in the past week about 10 of them
Usually u hear clicking behind the clove box area

Stop leak can and will clog the heater core, feel the two heater hoses that go into the firewall, both should get very hot! If one is cold, heater core is blocked, if both are hot, temperature blend door in the plenum is stuck.

With the temperture ok, you might have a clogged heater core. Check to see it either hose gets warm. Disconnect the hoses and back flush the heater core a couple of times.