Jandry Legacy pool heater with Fault High Limit on read out

[frisbeguy]

This year when I turned on my heater, I received the Fault High Limit statement on the display panel. Where do I start to attempt to repair it. My transformer has been replaced, so I know that the heater is getting power now. Any suggestions would be great. I called the local pool company and they informed me that it will be three weeks or more to come out and just look at it.

 

[danpik]

There are two high temp limit switches in series on these according to their manual. One or both may be defective and as such telling the unit the water temp is too high. I don't have any specs as to what OHM readings these should be when good. Usually there will be a published reading at a certain temp range to verify if it is good or bad.

Dan

 

[frisbeguy]

Before I attempt to replace the high limit switches, I am going to try to check the wiring to them and the circuit board. I believe before I attempt to remove them, I have to stop the water entering the heater, otherwise it will be messy. My problem is that there is no shut off valve on the swimming pool return line coming from the pool to the heater. Any other helpful suggestions?