I recently got my coolant flushed and fixed a leak also got a new thermostat but my car temp gauge keeps going up and down and now my engine fan stays on while driving it only turns off when car turns off.
My car has 139000 miles.
My car has an automatic transmission.
Hi there - either the recent cooling system work did not thoroughly bleed all the air out of the system, or you still have a bad thermostat - even the new one. A properly working thermostat should manage coolant temperature so that the gauge is steady in the center of the gauge. I recommend an overheating inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.