Pentair MasterTemp 400 heating but not getting to temp.

[jbailey0402]

I have a heater for a spa and pool that I replaced the stack flue sensor on. A rat had chewed through it. The heater works now and will get to 93 degrees but never higher. I hear a clicking noise coming from my control board and the board display seems to be raising and lowering the numbers for the temperature. I am not sure if it is a board issue, a switch pad issue, or if there could be another issue. I hate to just start buying parts without asking a question first.

Any help would be greatly appreciated.

Thanks in advance.

 

[ps0303]

Check the thermal regulator. See if it is gunked up.