My son has a 2004 Honda Accord EX 2.4L. The interior heat stopped working and he can't defrost his windows in the morning.
Here are the things I've done to fix the problem:
- Replaced the thermostat
- Replaced the water pump
- Replaced the radiator (it was old and in bad condition)
- Back flushed the heater core -- it flushed out with no issues
- Back flushed the entire cooling system -- no apparent issues
Having done all of this, there is still no heat coming from the interior vents in his car. After running the car hard for a while, the top radiator hose gets hot, but the bottom does not. This makes me think the thermostat is not working, but I tested it in boiling water and it does open.
Any help would be appreciated.