240SX 1991 running cold all the time........

[amolao]

I just got a coupe 1991 240SX, and a few days ago I noticed that the temp gauge stays on the lowest setting after I get on the road and only around 20 miles goes up a little bit and then goes down to "C" again...Im also running the heater and doesnt get any warmer inside the car. Will it be the thermostat???? Or the coolant mixture ratio???I dont want to keep running the car this way and break something major...

thanks

[Meantime]

Sounds like the thermostat is stuck open and not allowing coolant to reach operating temp. Pretty easy fix.