jacuzzi z140/H850000

control box balboa #276000

control panel H1930000

when power is turned on, the heater light appears on the control panel for a second and after that it disappears even though heater knob is turned all the way up. Jets work OK, except no heat. Thanks for your help,

Mario

not sure of error codes for your spa, but generally a lack of indication of heat is due to poor flow (normally a flow error) - remove your filters and try without them - may need cleaning or replacing (if over 2 years old)

Sounds like a flow issue- as alacy mentioned, if filters are clean and flow is adequate, either adjust or replace the flow switch.
Have you ohm'd out the press/sw while the spa is running (remove leads from press/sw to ohm it out)