How to Troubleshoot the Heating in a Nissan Pathfinder SEby Alibaster Smith
The heater core is the essential component in the Pathfinder SE's heating system. If you are having problems with a lack of heat and you are trying to troubleshoot the issue, the heater core is what you will be testing. The test is simple and will quickly show you what is wrong.
Turn the heat to the highest setting.
Turn the fan to the highest setting.
Start the engine and wait for the vehicle to warm up to normal operating temperature. As the vehicle warms up, coolant from the cooling system will enter the heater core and the fan should begin to blow warm air into the cabin. If the fan is not blowing warm air or is blowing warm air but you suspect that it should be warmer, then the heater coil assembly may have failed or is failing. If the fan will not blow, then the fan assembly may need to be replaced.
Open the hood and check for engine coolant leaking from the radiator or any hoses running from the radiator to the heater core, which is mounted on the firewall. If there are no leaks, then the heater core needs to be replaced by an experienced mechanic.