When it's cold outside, you need the heater to work in your Toyota 4Runner. If it’s not working, you want to find a solution as quickly as possible. There are a number of reasons that your heating system may not be working. Here’s some help with fixing your heating issues.
Do You Feel Heat On Your Feet?
If you feel even the slightest amount of heat, then your heater core is filling up with liquid, so the problem is not there. If it is a slight trickle of heat, it is quite possible that the fan is not working. You can check the fan by trying it at different speeds. If you get no response from the fan no matter what speed you put it on, you will want to check the fuse to the fan. If you get some fan at a different speed, then you have a dead speed on your fan.
If you are getting no heat at all on your feet, then the heater core is not included in the circulation of hot coolant when the engine is warmed up.
Next, Check These 3 Things:
Coolant Level – Make sure that you have enough coolant in the radiator. Too little coolant will result in no heat.
Water Pump – If the coolant level is fine, then the water pump may not be circulating the water throughout the system. The first symptom of this would be that the 4Runner is running either hot or overheating.
Thermostat – If you are not having trouble with overheating or running too hot, you may have a thermostat that has become stuck closed. If it is stuck, there will be no heat. Replace it by removing the lower radiator hose and putting a new thermostat in the truck. Read a repair manual for the Toyota 4Runner for instructions on how to replace the thermostat.
If you still cannot find the problem or you run into any trouble, you should consult your local dealership for assistance. Also, remember to only use genuine Toyota parts for replacements to avoid any premature wear or failure.