What you do is take it to a trusted mechanic and have them determine why it is overheating. Can be defective cooling fan, thermal relay, stuck thermostat, clogged radiator, or much more serious, a blown head gasket. DO NOT keep driving this car in this condition.
Probably a bad thermostat.
most likely thermostat stuck less than $ 15 part
Low coolant?Bad thermostat?System airbound?Bad water pump?
You should check the thermostat and the fuse for the heater.
Check the 1991 Legacy for a stuck thermostat. Check to make sure that the water pump is working properly.
Either the thermostat is stuck shut of the water pump is bad. Make sure that the coolant is full as well, then check the thermostat and pump to see why the coolant isn't flowing.
Replace Thermostat
overheating, or running too cold
If your engine is overheating and the heating system is blowing cold air, it may indicate low coolant levels, a malfunctioning thermostat, or a failing water pump. Low coolant can prevent proper circulation, leading to both engine overheating and inadequate heating. Check the coolant level and inspect for leaks; if the coolant is sufficient, the thermostat or water pump might need replacement. Ignoring these issues can lead to more severe engine damage, so it's best to address them promptly.
Most likely the engines thermostat is stuck closed. Probably low coolant level. No flow, no heat. Now where did the coolant go ??
Yes you definitely need a thermostat to keep engine from overheating + or overcool,g especially in cold weather.
check your water or coolant level If coolant level is ok, replace the thermostat.