Tempstar Furnace E1 Error Code — What It Means
The Tempstar E1 error code indicates a pressure switch fault — the control board energized the inducer motor but the draft pressure switch did not close within the required time window. The pressure switch proves that the inducer is creating adequate draft (negative pressure) before ignition is allowed. If the switch doesn’t close, the board aborts the heating cycle and stores E1. Tempstar furnaces are manufactured by ICP/Carrier and share the same diagnostic platform as Heil, Arcoaire, and Comfortmaker.
Common Causes
- Blocked flue or intake pipe — A partially blocked vent pipe creates back pressure that prevents the switch from reaching its cracking point.
- Condensate in the pressure switch hose — Water accumulates in the rubber hose connecting the inducer to the pressure switch, blocking the pneumatic signal.
- Failed pressure switch — The diaphragm cracks or the switch contacts wear, preventing it from closing even with correct draft pressure.
- Weak inducer motor — A motor drawing reduced speed due to worn bearings doesn’t generate enough draft to trip the switch.
Step-by-Step Fix
- Inspect the flue and air intake — Check both PVC pipes (90%+ units) from the furnace to the exterior termination. Clear any bird nests, debris, or ice.
- Drain the pressure switch hose — Disconnect the small rubber hose between the inducer housing and the pressure switch. Blow it clear with compressed air or drain any water. Reconnect securely.
- Test the pressure switch — With the inducer running, use a manometer to confirm the switch is receiving adequate negative pressure. Compare the reading to the pressure rating on the switch label. If pressure is correct but switch doesn’t close, replace the switch.
- Listen to the inducer — The inducer should start immediately on a heat call and reach a steady, consistent hum. A laboring or intermittent sound indicates bearing wear or a partial obstruction in the housing.
- Check for condensate overflow — On 90%+ furnaces, inspect the condensate trap and drain line. A blocked drain can back up into the inducer and pressure switch circuit.
- Reset and confirm — Power off for 30 seconds, restore, and call for heat. The inducer should start, the pressure switch should close within 30 seconds, and ignition should follow.
Parts Often Needed
| Part | Notes |
|---|---|
| Draft pressure switch | Single or dual-port; match cracking pressure specification from label |
| Pressure switch hose | 3/16” or 1/4” silicone tubing |
| Inducer motor assembly | Match HP, frame, and flange dimensions to the original |
Need Replacement Parts?
Finding the right replacement parts for your equipment is critical to getting it running again. Check current prices on Amazon — prices and availability change frequently.
When to Call a Pro
If the flue is clear and the pressure switch tests in-spec but the fault persists, have a technician check the inducer’s RPM output and verify the pressure switch cracking pressure against the manufacturer specification for your specific model number. Over-matched or under-matched switches cause persistent false faults.