Mastertemp 400 - Won't ignite

[Justantru]

Hello,

My mastertemp 400 heater does not recycle and service heater light turns on immediately. The "High Limit Switch" error code is highlighted on the control board. Does this just mean I need to replace the high limit switch?

 

[ajw22]

Test the HLS continuity using a multimeter. If the HLS is open when the heater is cold then the switch fails and needs replacement.

Does it throw the HLS fault before the heater starts up?

 

[Justantru]

Test the HLS continuity using a multimeter. If the HLS is open when the heater is cold then the switch fails and needs replacement.

Does it throw the HLS fault before the heater starts up?

Yes. I order a new switch and will have it installed tomorrow. If that does not work, what is my next step?

 

[ajw22]

See what error you get after you replace the HLS.

 

[Justantru]

See what error you get after you replace the HLS.

Thanks for your help. Paid $30 for High Limit Switch. Swapped out the old for the new and Heater works again.

 

[ajw22]

 

[Justantru]

Sorry to bother you, but I am still having problems. The heater is now working for a while, but cycles to service for 10 min or so then turns back on. It takes forever to heat the SPA. Thoughts on my next step?

 

[Justantru]

Thermal Regulator solved the problem.