System error H400 - Sharp AL-1655CS Copier

you need to reset it

Main heater lamp abnormally low temperature detection is what i found on a chart

make sure water filter is CLEAN ! this will throw a code

It could be the transformer, failed. Check for the secondary voltage out of the transformer. Should be around 24-28 volts.

Communication error

If communication between the ignition board and the display board is not established

within 3 s of power-up an error will be displayed. After communication is

established, if it is lost for 30 s, the error will be displayed. The error code will
be cleared upon a valid data exchange between boards.

My heater worked ok , btu made a clicking sound, now it shows a AO error? What can I do I dont have enough money to call a pool man again.

http://akamaipix.crutchfield.com/Manuals/052/052SDH400.PDF