Toyota Repair: temperature hi, 1990 toyota camry, electric cooling fan

Question
Hi ted,
    I have a 1990 toyota camry 171000 miles well maintained. Just today the temp gauge started climbing past the midway point toward the hot side.  I checked the radatior which was full with coolant.  Also no leaks found. Can you advise me of what to do? Thermostat defective?
Thanks in advance.
Stan


Answer
Replacing the thermostat is the cheapest and fastest way to see if it is the problem without going through a lot of diagnostic procedures, if that doesn't help then the next most likely cause may be a partially restricted radiator or the electric cooling fan is not turning on.