We had always wanted the EC150 to be operating in automatic heater mode.  According to our SE wiki entry, the heater volts should be set to -2.  One (7m.dcs?) that I checked several days ago seemed to be frosting up and had the setting at -1, which I don't know the meaning of.

Just to be sure, I've just reset all 3 levels of both TTs to be -2 via:

rs x

<cr><cr><cr>

P<cr>

2718<cr>

S<cr>

M -2 <cr>

Y<cr>

I used a really wide screen and looked for ASCII messages at the end of the lines to confirm my entries, but basically you are typing in the blind (and have to do this quickly before the EC150 times out) while binary messages are streaming by.

If we see frosting-up behavior on other EC150s, we can repeat this on the other sensor positions.