Symptom

Problem

Solution

The A25 is not sensing properly.

The sensing element may not be extended into the airstream or the sensing element is contacting an object inside of the duct (or plenum).

Insert the sensing element as far as possible into the airstream without allowing it to contact any object inside the duct (or plenum).

The system does not operate.

Incorrect switch connections or improper wiring.

Damaged sensor. The A25 is tripped.

Ensure that the wiring connections follow the wiring diagrams in the Wiring section.

Check connections. Replace the A25. Reset the A25.