On the covered Kenmore gas water heater, LED flashes 3 times every 3 seconds means Kenmore's service table lists this code as: air pressure switch open. First, make sure there are no blockages in the blower or venting system. Then: check for proper venting according to the installation instructions. A long vent or blocked vent can prevent the pressure switch from closing when blower is running. NOTE: The blower high-limit switch is wired in series with the air pressure switch. Ensure blower high-limit switch is not open. Check for electrical continuity across high-limit switch and replace switch if contacts remain open. Parts named: air pressure switch, High-limit switch, Gas control.
Differential
Likely causes of “Kenmore gas water heater showing LED flashes 3 times every 3 seconds”, and how to tell them apart
- 1
A blockage in the blower or the venting system
What separates it The LED flashes 3 times every 3 seconds while the blower runs
How to confirm Look for a blockage in the blower and along the vent; the chart starts there
- 2
A vent that is too long or blocked for the pressure switch to close
What separates it The install has a long vent run and the switch never closes when the blower is running
How to confirm Compare the vent to the installation instructions; a long or blocked vent stops the switch closing
- 3
A blower high-limit switch that is open
What separates it The high-limit switch is wired in series with the air pressure switch and has tripped
How to confirm Check for continuity across the blower high-limit switch, with the power off
- 4
An air pressure switch that will not close
What separates it The vent is clear and the high-limit switch is closed but the fault repeats
How to confirm Have the contacts checked and replaced if the chart's steps do not clear it
Before you touch a setting
Record this first — changing settings destroys the evidence
- That the LED flashes 3 times every 3 seconds, the air pressure switch open pattern
- How long the vent run is and whether anything blocks it
- Whether the blower high-limit switch shows continuity
Try in this order
0 of 5 completedWhat to do first
ReversibleMake sure there are no blockages in the blower or venting system.
Correct only the documented fault domain
ReversibleCheck for proper venting according to the installation instructions. A long vent or blocked vent can prevent the pressure switch from closing when blower is running. NOTE: The blower high-limit switch is wired in series with the air pressure switch. Ensure blower high-limit switch is not open. Check for electrical continuity across high-limit switch and replace switch if contacts remain open. Parts named: air pressure switch, High-limit switch, Gas control.
Make sure there are no blockages in the blower or the venting
ReversibleCheck for proper venting against the installation instructions, because a long or blocked vent can keep the switch from closing while the blower runs.
Check the blower high-limit switch
ReversibleThe chart notes the high-limit switch is wired in series with the air pressure switch, so an open high-limit gives the same 3-flash pattern.
Replace the high-limit switch if the contacts stay open
ReversibleTest for continuity across the switch with the power off; the chart replaces the high-limit switch if its contacts remain open, and names the air pressure switch and gas control as the other parts.
Model-specific
What is true of this model and not of its siblings
- Parts named by the chart
- Air pressure switch, high-limit switch and gas control.
Stop boundary
When this stops being a self-service repair
- !Do not run the heater with a blocked vent while you investigate the 3-flash fault, since the pressure switch is protecting against poor venting
Evidence ledger
Sources behind this answer
Where the manufacturer's article stops. The vent check, the series high-limit note and the continuity test are chart text; the gas leak advice is general safety guidance.
Exact questions
Common questions
What does LED flashes 3 times every 3 seconds mean on a Kenmore gas water heater?+
Kenmore's service table lists this code as: air pressure switch open.
Can a long vent cause it?+
Yes, the chart says a long or blocked vent can prevent the switch closing.
What is wired in series with the switch?+
The blower high-limit switch, so check that it is not open.