Here is the link of the installation manual. Search for outdoor temperature lockout. The default is 40 degrees. You can change it in increments of 5 degrees.

I would be curious to know why the WA code says you can't change the lockout. It doesn't make sense to me.

Here is a link that might be useful: Honeywell THX9321

Thank you Mike, with your help and link I found how to get the right password code to get to installer menu, but, I don't know what to do from there do I do a reset on outside sensor menu?

I am not familiar with this thermostat. I am going by what is in the manual.

Page 15 shows a picture of the installer options screen. You need to edit ISU 3120 (page 24). See if you can display the current value and edit it. Also look at page 62. You should be set up so that the heat pump and the electric back up can run at the same time. There are two lockout temperatures (heat pump and electric backup). The manual does not explain well how each is set.

I recommend you change one thing at a time. Take pictures and notes in case you have to go back and make changes.