Hayward H400FDN Universal H Series Troubleshooting Guide - Page 48

LO is NORMAL when the pump is turned off.

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11. Service LED ON: "LO" Code "LO" Code (Limit Open) may relate to water flow. Verify the pump is running & adequate water is flowing through heater. "LO" is NORMAL when the pump is turned off. Inspect water pressure switch Step 11A Continuity test Step 11B Inspect the water pressure switch wiring, ensuring wire harness terminals are securely fastened. IF damaged, replace wire harness (pg. 20). IF secure and free of damage, go to step 11B. Remove wires from water pressure switch & measure continuity across terminals (while pump is running). IF open, replace water pressure switch. IF OK, go to Step 11C. 48

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Inspect the water pressure switch wiring, ensuring
wire harness terminals are securely fastened. IF
damaged, replace wire harness (
pg. 20
). IF secure
and free of damage, go to step 11B.
Continuity test
Inspect water pressure switch
48
“LO” Code (Limit Open) may relate to water flow. Verify the pump is running &
adequate water is flowing through heater.
“LO” is NORMAL when the pump is turned off.
Remove wires from water pressure switch &
measure continuity across terminals (while pump
is running). IF open, replace water pressure switch.
IF OK, go to Step 11C.
11. Service LED ON: “LO” Code
Step 11A
Step 11B