Pentair Mastertemp 400 display all black squares

jeffchap · Mar 27, 2024

Just put this heater in new last season and tried to start it up today for the first time, only to have the display come on, but all the fields are just black squares.

Has anyone ever experienced this or have any idea what to do about it before I call a service tech?

Thanks!

ajw22 · Mar 27, 2024

What state is your Aqualink and pump?

Have you cycled power to the heater?

Is the heater controlled by your Aqualink?

Is the Aqualink calling for heat?

jeffchap · Mar 27, 2024

Yes to all, pump is running.

I just started holding down buttons and the heater fired up and is running now. The display is still all boxes though. I watched as I powered it up again and the version info was displayed properly briefly before it went into this state, so I know the display works.

Oh well, at least it's heating. That'll give me some time to troubleshoot. Having family over this weekend to swim.

ajw22 · Mar 27, 2024

Make a warranty claim with Pentair. Your connected MasterTemp has a different board, firmware, and display and may have some bugs in it.

jeffchap · Mar 27, 2024

After a while, the display finally came on. I will keep an eye on it and see if it does it again.

ajw22 · Mar 27, 2024

jeffchap said:
After a while, the display finally came on. I will keep an eye on it and see if it does it again.View attachment 560882

Interesting warm up problem.

What was the air temperature overnight and when you started the heater?

Some LCD displays do not like working in the cold.

jeffchap · Mar 28, 2024

ajw22 said:
Interesting warm up problem.

What was the air temperature overnight and when you started the heater?

Some LCD displays do not like working in the cold.

It was about 50, and I considered that. But it displayed the version info correctly at startup prior to changing to the black squares.