Honda Heater Not Working?
The most common cause of warm air not circulating when the heat is on is the heater core, but there are times when it is not the core that is at fault.
Issue: My heater blows cold air
What to do:
The problem could be that the water shut off valve in the front heater core is broken. Open the hood and look down and to your left. There is a control cable that comes through the firewall.
* Slide the cable off the lever.
* If lever and screw on top do not move together, it is broken.
* You can get heat by using a Phillips head screwdriver and turning the screw clockwise.
* Replace the valve to fix the problem.
Issue: My blower stopped working...the heat is on, but no air is coming thru the vent
What to do:
* Check the fuse to make sure that you do not have a bad fuse.
* Replace the fuse if you have blown the fuse.
* If the blower is not working at all, you may need to replace the blower motor transistor.
* If the blower only works at high speed, it is the blower motor resistor. Blowers usually only work at one speed, but the resistor is used to regulate the speed, so if you are only getting one speed, it is the resistor.
* Replace either the transistor or the resistor.
Issue: I am not getting any heat
What to do:
Since a couple scenarios can cause this, here are some of the most common places to check for problems:
* Make sure the belt on the air conditioner compressor is in good shape and operating properly. You may need to replace the belt if it is worn or torn.
* Check all the hoses on your air conditioning system to ensure that there are no leaks or tears that can cause the fluids to leak out. Replace any worn or damaged hoses.
* Check your condenser for debris or other things that may be blocking it. You can use a can of compressed air to blow out any debris.
* If you find that you have damp carpet in the front passenger foot well, then you may be leaking antifreeze. You will need to replace the heater core.
* Check the thermostat to ensure that it is not stuck open or closed. If it is stuck, replace it.
Your heater hoses in the engine compartment should both be warm. If one of them is not, then it may be blocked or the heater core or control valve is not working properly. Disconnect the hose and back flush the core using a water hose. If it is still blocked, remove the hose and completely flush it out. A core needs to be replaced if neither of these things works to fix it.
Issue: My heater is not blowing warm air.
What to do:
Look under the control panel on the passenger side of the car. There is a cable the controls the air mixture into the cabin. If it has popped off the valve, that will stop the air from flowing. Put it back on and it should work fine.