Heater Not Blowing Hot Air
If the engine reaches normal temperature but the vents blow cool, the problem is in the heater core or the blend door, not the engine.
What it feels like
- Lukewarm air at best, even with the fan on high and the temperature at max
- The temperature gauge sitting lower than it used to
- Heat that works at idle but fades while driving
- A faint sweet smell through the vents
Codes that usually produce this
Check these first, in this order
Free checks first. Nothing here costs money except the fuel you burn.
- 1
Watch coolant temperature on the scanner once warm.
What you'll see195F to 220F. A reading stuck near 160F means the thermostat is open all the time.
- 2
With the engine warm, feel both heater hoses at the firewall under the hood.
What you'll seeBoth hot. One hot and one cold means the heater core is blocked.
- 3
Check the coolant level in the reservoir with the engine cold.
What you'll seeBetween the marks. Low coolant means air in the core and no heat.
Stop and get it looked at if
- The temperature gauge climbs while the heater blows cold.
- You smell coolant inside the cabin, which means a leaking core.
- The windshield fogs with an oily film that will not clear.