Sounds like you are low on coolant. Is the low coolant light on? IF it's not on and you are full on coolant try the following 2 ideas. # Your thermostat could be sticking. You need to replace it. Its not hard to do but it's a little more expensive than a standard car. The water neck and thermostat are all part of the same unit. Last time I priced one it was 50-60 dollars. # OR if you low coolant light was on and you filled it up you could still have air in your system. It needs to be bled out.
Probably a bad thermostat.
faulty control valve on heater or air in the lines
Coolant level is probably low, Have it checked for an antifreeze leak.
most likely thermostat stuck less than $ 15 part
Low coolant?Bad thermostat?System airbound?Bad water pump?
sounds like the head gasket ...same thing just happened in my 97 cavalier
Is the AC condenser in your system blowing cold air?
One reason is engine overheating - check your temp gauge and coolant as a first step.
Check the 1991 Legacy for a stuck thermostat. Check to make sure that the water pump is working properly.
If the fan is moving and blowing cold air, your cold air intake is working properly. So long as your car isn't overheating it's a safe bet that the intake is functioning properly. Quite simply your temperature gauge will head straight for the red if the engine isn't getting cold air.
This is probably the furnace overheating. Usually overheating happens when the filter is too dirty and restricts airflow, causing the limit switch to shut off the burner.
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.