DA40NG factory Air Conditioning issues

[aeromomentum]

I have a 2022 DA40NG with the RACC II AC System (powered by an additional alternator). The additional alternator is not working and this seems to be a common issue. The problem started intermittently and now will not turn on at all. My mechanic removed the alternator and tested it on an alternator test bench that spun the alternator and used a voltage regulator that is part of the test equipment. It perfectly passed the bench test. He also checked the wiring and it seemed to pass all his tests. He then reinstalled the alternator and replaced the regulator but it is still not working. With the engine not running, the red "field fault" LED on the regulator is on. We have not checked this with the engine running. The voltage of the small batteries for the additional alternator is 25.3V at the alternator.

What should I suggest to him to try next? Does anyone know what the common failure mode is for the additional alternator system on these aircraft? While my mechanic is good and has a fair amount of Diamond experience and is certified on the Austro engines, he does not have any past experience with these AC systems.

[alanhawse]

I have a 2022 DA40NG with the RACC II AC System (powered by an additional alternator). The additional alternator is not working and this seems to be a common issue. The problem started intermittently and now will not turn on at all. My mechanic removed the alternator and tested it on an alternator test bench that spun the alternator and used a voltage regulator that is part of the test equipment. It perfectly passed the bench test. He also checked the wiring and it seemed to pass all his tests. He then reinstalled the alternator and replaced the regulator but it is still not working. With the engine not running, the red "field fault" LED on the regulator is on. We have not checked this with the engine running. The voltage of the small batteries for the additional alternator is 25.3V at the alternator.

What should I suggest to him to try next? Does anyone know what the common failure mode is for the additional alternator system on these aircraft? While my mechanic is good and has a fair amount of Diamond experience and is certified on the Austro engines, he does not have any past experience with these AC systems.

I have had a few issues with the ac in my 2022 airplane as well.

The simple answer is call James spearman at Spearman Aircraft ... James.spearman@spearmanaircraft.com ... he can always fix weird Diamond issues.

Alan

[aeromomentum]

Hi Alan,

What issues have you had with your AC? How were they fixed? When it was working, mine worked great on the ground but not as well when flying, especially when climbing. I think the location of the condenser hot air exit is not in a great location but there is nothing that can be done about that.

Mark

[alanhawse]

Three problems over the last two years...

The switch

A relay

The control panel

Alan

[aeromomentum]

My AC is fixed! It ended up being the alternator brushes. While the alternator had tested good on the test bench, the brushes were worn and intermittent. The mechanic should have visually inspected them when he had the alternator off the first time.