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Honeywell M9185D 1004 Modutrol
Can anyone tell me how to troubleshoot a Honeywell M9185D Modutrol with a T991A Potentiometer controller?
It runs a Honeywell modulating water valve for a heat recovery unit in a nursing home. The valve stopped modulating. I can open it by jumping the 24 volt Red to Blue, it will open the valve. I got the manual off the Internet but it doesn't tell me how to troubleshoot/test it electrically. I understand how it works, just not how to test it.