An HVAC controller may include a user activated performance test for monitoring the performance of a connected HVAC system. In some cases, the user activated tests may cause the HVAC controller to operate the HVAC system and identify a current delta T of the HVAC system. In some cases, the identified current delta T may be displayed on a display of the HVAC controller for viewing and/or evaluation by the user. In some cases, a delta T limit may be accepted from the user through the user interface of the HVAC controller. In some cases, a minimum run time may also be received via the user interface of the HVAC controller. The delta T limit and/or the minimum run time may be based, at least in part, on the current delta T identified by the user activated performance test.