Dorma Kaba model 79 won’t open and keeps blinking red and yellow when opening the door.

If your Dorma Kaba model 79 lock only flashes yellow and red lights, then you need to determine the number of times the yellow and red lights flash to determine what is wrong.

According to the Dorma Kaba LED Diagnostics user manual, You can determine where the problem is based on the number of flashes of the yellow and red lights below and fix it:

• Yellow and red flash four times (together) when the keycard is used: Lock cannot read all the information on the key, and the key may be damaged or not properly encoded.
  • Try using the key in the Lock again to make sure the key is being used properly.
  • The Lock may need to be cleaned (use a cleaning card in the lock)
  • Try making a new keycard and use the new keycard in the lock.
• Red and yellow lights flash together for 6 seconds when the keycard is used (the door will not open, it is in privacy mode): Lock’s time and date must be updated.
• Yellow and red lights flash alternately for 6 seconds (when the keycard is used Lock will not open): Lock’s batteries must be changed.

I hope the above solution will be helpful to you.

For more information about the Kaba door lock problems and troubleshooting, please check this article: Kaba Door Lock Troubleshooting: Expert Step by Step Guide.