The processor at the bottom of my Unison DRd says "Fan Fail." What does that mean?
Description/Explanation of Issue
The fan on your dimming engine is powered by 24VDC from the dimming engine. The dimming engine has a current sensing circuit built into it. If the fan is damaged and unable to run, that circuit can't sense the current—resulting in the Fan Fail error.
R6 (R9173-F) and Q2 (Q9005-F) on the dimming engine are often faulty when fan failures are DRd related, and they will often show scorching. Q1 (Q9023-F), Q3 (Q9001-F), and CR1 (CR9023-F) may also have failed.
It should be noted that the failed DRd components can be damaged again after repairs if the fan is still bad.