Intermittent overheating & interior fan on 2000 BMW 323i

Intermittently the engine overheats and the cooling fan does not go on; thermostat has been replaced; is it the fan relay?
Interior fan at times goes on & off with no key in ignition

Asked by for the 2000 BMW 323i
Replace fan speed resistor for the interior fan issue.
Check the wiring and readings of the coolant sensor connected to the bottom radiator hose. Does the fan kick in when A/c is actuated? as this should be your stage 2, which is also your overheat stage.
Check water pump. The impeller could be free spinning on the shaft
The fan does not always kick in when the A/C is turned on. The mechanic that looked at it said it's the fan module; I will mention your suggestion.
Thank you.