Condition
Furnace Not Starting at All
No blower, no ignition attempt. Thermostat, power, or control board.
Possible Causes
Incorrect Thermostat Calibration
If the thermostat fails to sense the correct temperature, it won't signal the HVAC to run.
Root Cause Analysis →Diagnostic Tests
- Jump R to W
- Check 24V
- Verify heat mode selected
Repair Options