The under pressure low alarm indicates that there were issues with pressure build-up. Normally, the motors should regulate after a few seconds.
When the roaster is turned on, the motors run at the previus settings, so you should give them time to adjust. Do not press the emergency stop, let the motors regulate themselves. Then the noise will diminish little by little…
Another possible cause for this alarm could be an air leak. Make sure that the side doors and the covers under the cooling tray are securely closed.
Check whether the motor fan rotates or is stuck. If it's jammed, there may be dirt preventing the fan from rotating, so you'll need to open it and clean it. Also, ensure that the fan is not deformed. (If it is deformed, you can order a new one through your local dealer or via Giesen Coffee Roasters Store
You can attempt to power off the machine for 5 minutes to perform a full reset. (This is only applicable if the motor can rotate). This will not be helpful if the motor is stuck.
Follow these instructions to assess the functionality of the motors:
Disconnect the chimney from the machine, turn on the burner, press F4 only once, then record a video showing the disconnected chimney before turning on the burner and share it with us.
If the roaster works without any problems when the chimney is disconnected, it's certain that the issue does not lie with the roaster.
Additional questions:
How long is the chimney till the outside and how many bends does it have?
Do you have a bend or a cap on the outside of the exhaust pipe?
When was the last time you cleaned the entire exhaust pipe?
How many roasting hours has the roaster accumulated since the last maintenance cleaning?
I've attached the cleaning guide in case you need it.
