Lennox MPA009S4S Service Manual page 119

Error Code:
P2
Description: Low pressure switch open.
General Note: If the sampling voltage is not 5V, the LED will display the failure.
Refrigerant is not enough. Add the refrigerant.
Is the wiring between the low pressure switch and
main control board is connected properly.
Is the low pressure protector broken?
Method: Disconnect the plug. Measure the resistance
of the low pressure protector, if the protector is normal
Check whether the outdoor ambient temperature is to
Check whether the high pressure valve is opened.
Check if the indoor fan runs properly in cooling mode.
Replace outdoor main board.
Low Pressure Connection
No
Yes
the value is 0.
Yes
low.
No
Yes
Yes
No
Connect it properly..
No
Replace low pressure protector.
Yes
No
Fully open the high pressure valve.
Refer to the solution of fan speed mal-
No
function (E8). Find out the cause correct
119
Stop the unit.
it.