Honda civic 2004 vetec executive
Hello i have an honda civic 2004 vetec
executive hatchback . I am facing an issue
since i bought this car its heater was not
working . Cold air was coming out of it . I
take it to mechanic and he said we need to
change its thermostate which he changed
but after that it start another issue now when
i driving on motorway the temperature guage
gets to high level sometime and suddenly it
come down when i stop the car is driving
normal but still temperature meter go to full
high ? What will be the issue ?