Troubleshooting, Overview – Siemens 125-1957 User Manual
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Siemens Building Technologies, Inc.
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Troubleshooting
Overview
This chapter describes corrective measures you can take should you encounter a problem 
when using a Unit Vent Controller. 
You are not required to do any controller troubleshooting. You may want to contact your local 
Siemens Building Technologies representative if a problem occurs or you have any questions 
about the controller. 
NOTE:
When troubleshooting, record what the problem is and what actions were 
performed immediately before the problem occurred. Being able to describe the 
problem in detail is important, should you need assistance from your local 
Siemens Building Technologies representative. 
Basic Service Information
Always remove power to the controller when installing or replacing it. Since the controller 
does not have a power switch, the recommended method of removing power to a locally 
powered controller is to turn OFF the power to the 24 Vac transformer. The recommended 
method of removing power to a controller on a power cable (even to service a single 
controller) is to turn OFF the power at the transformer. 
NOTE:
When removing power to a controller to perform maintenance or service, make 
sure that the person in charge of the facility is aware of this and that appropriate 
steps are taken to keep the building in control. 
Never remove the cover from the controller. There are no serviceable parts inside. If a 
problem is found with a controller, contact your local Siemens Building Technologies 
representative for replacement. An anti-static wrist strap is recommended when installing or 
replacing controllers.