First post so here goes
I have a Pentair Mastertemp 250 heater and it's only a year old. Ran with a loud whine at times last year but worked fine otherwise. This year though it only runs for about 1 minute then the service heater comes on, shuts down for maybe 2 minutes then run again for a minute and the cycle just keeps happening until pool eventually gets to temperature. There is no error code on the display although I see here it says to check the back side of the board and I'm not sure what that means. On the youtube videos showing fault codes they all appear on the display where you normally see the temperature.
I checked the cartridge filter and cleaned it, pump is working fine, SWG is all good and clean. Water chemistry all good so the issue must reside with the heater itself.
I understand it's under warranty but I have been on hold for hours over multiple days with Pentair and have yet to speak to a rep and would like to fix it myself if it's a simple issue like a temperature sensor. Any advice appreciated