what does engine code p1299 means? I took my car to auto zone and they say to google the code they didn't have it?

P1299 - Cylinder Head Over Temperature Protection Active -- indicates an engine overheat condition was detected by the cylinder head temperature ( CHT ) sensor. An FMEM strategy called FAIL - SAFE COOLING was activated to cool the engine - low engine coolant level --- check your coolant reservoir level

Cylinder Head Overtemperature Protection Active

Radiator Coolant Level or Low Oil or timing or perhaps a leaking freeze out plug. Any or the failures that can cause a car to overheat should be checked. Sometimes it is two things but then u usually get more than one code.

Could the Radiator fan not working will cool at high speed A/C will start blowing cool air the fan not working at Idle A/C will get hot ? Fan bad not cooling engine?

Change cooling fan

My 99 grand marquis doing same thing. Changed cht sensor n thermostat with ford parts. Now fan wont come on unless a/c on so it overheats. Before change it just acted like it was overheating but never did.