Zehnder ComfoAir Q350 fault

[Build House Passiv]

We have a Zehnder ComfoAir Q350 and the front display no longer works but the green light is on behind where the PCB is located - the external control unit displays error codes for all sensors: codes 1023 1025 1027 1031 1039 1041 1043 1047 1049 1050.

Also, the unit powers on, fans are working but no extract or supply is coming out of the vents.

 

I reckon it is a faulty PCB board, am I right that I will need to replace?

 

Edited December 16, 2024 by Build House Passiv

[mike2016]

How old is the unit - was the warranty uplifted (2 years to 6 if you register within 6 months I believe)? If a full power off (disconnect from power) doesn't resolve it then it does sound like a PCB issue. Any power surges recently? 

[Build House Passiv]

Thanks, unit was manufactured in 2018 and installed in 2019 - unfortunately wasn't registered in 6 months. There was a power cut so most probably the cause but not immediate (main power to whole area switched off a few months before)! 

 

A full power off hasn't resolved it, it actually made the white dot light disappear on powering back on (previously the screen was black but has the white dot on still + all the error codes).

 

Edited December 16, 2024 by Build House Passiv

[gytis]

On 16/12/2024 at 11:44, Build House Passiv said:

Thanks, unit was manufactured in 2018 and installed in 2019

 

 

Have you solved this? I'm facing similar issue, though I don't have anything attached to verify error codes, but the display seems to be dead. It power up, does some self-checks (I guess?) cause the fans are blowing and the bypasses work, but then it stops.

Mine was also manufactured in 2018

[kreasteve]

Same fault here on a Q350 (firmware 1.7.0, SHT30): front display completely dead, green LED on the main PCB lit, and exactly these ten error codes. After a restart both fans ran for about a minute, then the unit switched off the fan for the supply air.

 

It was the outdoor air sensor (ODA, the "top" sensor), more precisely the corroded capacitor next to the SHT30 on its small board. With that sensor plugged in, the communication with the other sensors and the display was disturbed.

 

Quick check, with the unit unplugged from the mains first: unplug the outdoor air sensor at the main PCB. It is one of the two green connectors, on the side where your outdoor air duct is connected. If the display comes back and only SENSOR_ODA ERROR remains, it is that sensor.

I only replaced the capacitor (100 nF, ceramic) and coated the spot with conformal lacquer afterwards. All errors have been gone since, and I did not have to replace or rebuild the sensor itself.

 

A more detailed write-up with photos, fault-finding and the repair:
https://kreasteve.de/en/comfoair-q350-display-schwarz/

 

Steven