York Single Package Air Conditioner ZR120N10A2AAA50124A

Connect a manometer to the outlet pressure port on the gas valve to monitor the manifold pressure

Remove cover screws covering HI and LO pressure adjustment screws

Set thermostat to call for second stage heat and start furnace

Is the second stage manifold pressure within 3.5 IWG ± 0.3?

Check that all filters are in place

Inspect filters for dirt and debris

Do the filters need replacement?

Replace filters with the same size and type

Ensure filters are installed ahead of evaporator coil

Close main manual shut-off valve

Open the union fitting upstream of the unit gas valve and downstream from the main manual shut-off valve

Remove screws holding each end of the manifold to the manifold supports

Disconnect wiring to the gas valve

Remove the manifold & gas valve assembly

Gas Connection and Pressure Check

Open the main shut-off valve to admit normal gas pressure to the mains.

Check all joints for leaks using a soap solution or other suitable material.

Adjust blower speed to specific static and CFM requirements

Adjust belt tension as required

Tighten blower pulley set screws

Tighten motor sheave set screws

Have the set screws been re-checked after 10-12 hours of run time?