Tempstar 1 Flash

What does Tempstar 1 Flash mean?

On a Tempstar packaged gas/electric unit, the integrated gas unit controller (IGC) LED flashing once signals a limit switch fault. The normally closed limit switch opens when the leaving-air temperature rises above its maximum allowable setting, which breaks the control circuit and instantly closes the gas valve to stop gas flow to the burners.

Symptoms

• IGC LED flashes once instead of staying continuously on
• Burners stop firing while the call for heat continues
• Blower motor keeps running until the limit switch resets
• Unit fails to maintain the set heating temperature

Common causes

• Leaving-air temperature exceeding the limit switch maximum setting
• Restricted airflow over the heat exchanger
• Blower not delivering adequate heating airflow
• Temperature rise outside the unit's approved range

Diagnostic steps

1. 01

   Confirm the LED code

   Remove the control access panel and verify the IGC LED is flashing once, which Table 5 of the manual identifies as a limit switch fault.

2. 02

   Check the heating airflow

   Verify the unit is producing a temperature rise within the approved range stamped on the rating plate; excessive rise opens the limit switch.

3. 03

   Inspect for airflow restriction

   Look for a dirty filter, closed registers, or duct restrictions that reduce airflow across the heat exchanger and raise leaving-air temperature.

4. 04

   Allow the switch to reset

   The limit switch closes again once the air temperature drops to its low-temperature setting, after which the ignition system cycles and the unit returns to normal heating.

When to call a professional

Call a qualified service technician if the limit switch fault repeats after airflow has been confirmed as adequate, or if you cannot identify the restriction. The manual states this equipment is intended for service by a qualified technician familiar with safety procedures and proper tools. Persistent limit faults can indicate a failing blower, heat exchanger, or control problem that requires professional diagnosis.