Nissan Repair: thermostat 1991 maxima, upper radiator hose, clunker

Question
where is the thermostat in my 1991 maxima.  I just purchased this clunker and when i am driving down the high way the temp needle goes down past cold and doesnt blow heat any more.  when i am sitting still it heats up just fine... I think it is the thermostat But I dont know where it is

Answer
Joshua,

The thermostat is where the upper radiator hose connects to the engine.  But, it sounds like you have trapped air in the system.  Now, it could be that someone removed the thermostat and it just needs replacement.  Check these and email me back.