low temp

hey everybody, 93 grand am 3.1, the car has low temp gauge reading 120 , i replaced the thermostat a 2 months ago still the same ,full of antifreeze, purged for air bubbles, and the car has little heat if any, pretty sure heater core needes replacement but would that cause low temp reading? thanks for any advise :)

The guage could be off. Check the thermostat housing temperature with an infrared thermometer. If it too is 120, you probably got a bad thermostat.

Check both heater hoses. If both are about the same temp, the heater core is most likely not the cause. If there is a considerable difference, try flushing the heater core before replacing it.

If one hose is hot and one cold, take both hoses off. You will probably want to take them off on the engine side, since the heater core is very hard to get to in most cases. Using a garden hose, gently spray water backwards through the heater hoses/core. Once the coolant turns clear, reverse the water flow several times. Use compressed air IN SHORT BURSTS, between switching directions this will loosen any chunks. I usually top the system off with pure antifreeze, to make up for any water that may be left.

BTW- the 1993 Grand am has a 3.3 L (90deg V6).

It is also possible your temprature sending unit is bad, along with a clogged heater core.