If the air filter is dirty, excess pressure will build up across the filter, triggering the normally closed air pressure switch (PF) to open.
|Possible Cause||Component to Check||Recommended Action|
|Dirty air filter||Air filter. Open the middle-front panel to access the filters.||Replace air filter.|
|Switch tubing||Tubing leading to switch||Verify that tubing is clear and that it is not kinked|
|Incorrect wiring||Alarm wiring||Correct wiring. Refer to the Dirty Air Filter Alarm Wiring diagram below.|
|Incorrect air pressure switch setting||Arrow on the dial should be pointing at 250||Correct setting to 250.|
|Faulty air pressure switch||Air pressure switch||If the switch is open while the filter is clean and setting is correct, replace the switch|