Question about Jandy Laars LX Pool Heater / 400,000 BTU / Natural Gas

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My LX 400 is showing a service code EXT SW1. What to do?

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Sw1 code

fuseable link or vent switch open

Apr 07, 2014 | Jandy Laars LX Pool Heater / 400,000 BTU /...

1 Answer


Open up the front panel on the heater you will see 2 white wires going to the thermal fuse, pull both leads off the thermal fuse ,take a jumper wire and connect it between the two wires . Does the fan come on ? if so remove the jumper, if not put the leads back on the thermal fuse and remove the thermostat panel on the top of the heater on the right side there will be 2 screws on the bottom of the panel remove them and pull the panel up and out of the way as much as possible look inside to top right in about the middle of the heater you will see 2 white wires going to a switch (overheat switch) with a red button in the middle, push on that button and reset it, if the fan still does not come on take your jumper wire and put it between the 2 white wires on the overheat switch does the fan come on? If it does great but don't leave the jumper in , remove it and put in a new overheat switch ,but that only fixes the switch because there is still a problem of why that happened. First thing is to check the heat exchanger for soot build up or a blocked exhaust fan and check your gas pressure my guess is it is low. But do not run that heater with any bypass jumpers in or your asking for a fire .

Apr 14, 2013 | Jandy Laars LX Pool Heater / 400,000 BTU /...

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