Heater core must have coolant in it to produce heat. Fan switch ie sensor may need coolant over it to sense heat and kick on. You didn't mention anything about it having coolant in it.Bought this car about three months ago and has 119xxx miles on it. Yesterday I noticed some steam coming from the front, popped the hood and couldnt really tell where it was coming from. Temputure was fine. This morning my girlfriend was driving it and it overheated bad, gauge all the way up. She said that it was not blowing any warm air through the heater either. Im hoping its not the head gaskets. I checked the oil last week and saw no milkyness or bubbles, no leaks around the motor that i can see. My guess is that it could be one of two things
1. Fans not working: When i popped the hood the fans were not running and the car was.
2.Theremostat: If the theremostat was bad, it would not signal the fan control module to turn on right?
Any help on this would be awesome because we cannot be with out two cars. My girlfriend wont complain though cause she'll get to drive my WRX
A leak will cause steam - a leak will cause you to have no coolant, no coolant - no heat from heater core. No coolant engine over heats.
Thermostat needs to be stock Subaru the cheap parts store junk are famous for causing subarus to overheat given they don't open correctly with the odd cooling system subaru has.
Two things - first make sure it has coolant in it. Run it long enough to get the thermostat to open - check the rear left bottom corner of the engine ie looking from just behind the driver side front tire see if you have coolant dripping off the block/head gasket onto the hot exhaust. This is the classic HG external failure.
No coolant dripping off the back bottom corner - get a HG test kit which tests for exhaust gasses in your coolant. This will confirm that either the HG is fine or you have a failed HG internally which case your coolant is being drawn into the cylinder and messing up the engine and obviously exiting via the exhaust.
Water pumps rarely fail on Subarus but they still are a point of possible failure either no circulating the coolant or - leaking. So thats also on the suspect list.
A plugged up useless radiator can also kill your car and cause cooling system problems.
You now have a check list good luck
As for the fan's flip the AC switch on see if the fans kick on- it wouldn't be the first time someone has had their primary fan fail or even both the primary and secondary fans die.