Heat pump manual

You can download wiring diagram from:
https://www.mypiike.info/isuzu/isuzu-sbr-422-wiring-diagram.html

Bad wire, bad speaker or bad channel. Disconnect the wire from the amp. Using a 1.5v battery touch the wires to the battery briefly. You should get a pop from the speaker. If not get a different piece of wire and use it instead of the regular wire. If still no pop then the speaker is bad.

It was so amazing.

http://waterheatertimer.org/Review-GE-Heat-Pump-water-heater.html

Call GE and they will send replacement panel
Gene
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If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

http://waterheatertimer.org/Review-GE-Heat-Pump-water-heater.html
Scroll down to error codes, call GE for service.
Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

manual gearbox then its EP90

Define, attach and test them according to the manual.

This is the problem you have when you rely on "modern electronics". Suggest you buy a manual 'stat and just turn down the temp at bedtime. Make it cold and use a blanket, that is what we did in the " good 'ole days".