Fujitsu Heat Pump Control Board?

Specific Inspection Topics Inspecting HVAC Systems
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My own house - 11 year old unit, model AOU24RLXFZ. 1-2X per week lately the thermostats display “Err” and have a constantly blinking green light (no code or other info) and won’t run until I cycle the power off/on. How likely is is to be the control board do you think? I can buy one for a few hundred dollars which is about what it costs here on Maui to get an HVAC guy on site. I hate to just throw parts at things but am thinking it might be worth the gamble?

System has 5 zones and 2 outdoor units. The offending system is the larger of the two outdoor units that has three zones. All three indoor thermostats blink and have the same “err” code displayed when it’s acting up which makes me lean towards the common outdoor unit.

Fwiw, I’ve found Fujitsu HVAC equipment to be total crap but it came with the house and a full replacement of the system is probably 30K+. A couple indoor coils have failed and been replace and Fujitsu is so confident in their equipment that they give a robust 30-day warranty. :slight_smile: :slight_smile:

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"Multi-Zone Outdoor Units: AOU18RLXFZ, AOU18RLXFZH, AOU24RLXFZ, AOU24RLXFZH, AOU36RLXFZ, AOU36RLXFZ1”

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While it certainly could be the control board, does the unit have an independent power supply? Often when something works just fine and needs re-energized occasionally, it’s something flaky with the power. If it’s blown a few caps, those would be on the board, but it may be cheap to just replace any of the low voltage power supplies that power the control circuitry first. It’s probably 24V, so any decently sized industrial 24v ps can probably handle it without issue. You may have to splice it in. If you’ve got a decent DMM, look at where the voltage is sitting at on the board. It may be out of spec.

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