Subaru Blitzen overheating but heater blows cold air

Question

I have a 2000 Blitzen.

My heater blows cold air and tonight it overheated.

It is not losing water. Would this be the thermostat or an air blockage?

Answer 1

Low coolant can cause there to be no cabin heat because the coolant is not able to be circulated thru the heater core. I am surprised the mechanic did not check the coolant level.

Obviously, when the coolant level gets low enough (empty in your case) it can not be circulated thru the system properly, causing the engine to overheat.

The system will need to be filled properly and air bled. It would also be a great idea to have the cooling system pressure tested to ensure there are no leaks and it is working properly.

After the cooling system is working properly, if you still do not have heat, then it is possible the heater core is blocked.

Answer 2

Cold air indicates no coolant. You might have a simple problem of a leaking coolant bottle or broken radiator. You may have the dreaded Subaru Head Gasket issue. I'd get a sniff test done, to see if the coolant is getting into the engine, and a pressure test to see if the cylinders are all around the same pressure.

Do you have a Turbo, or is it the NA engine? Turbos are much less susceptible to head gasket failure than the NA engine (because of the way the block is forged). How many miles on the car? If it has over 105,000miles (169,000km), the timing belt is due for replacement (plus a lot of other work).

If you decide to change the thermostat, buy from a Subaru dealer. Regardless of what the car spares shops tell you, their versions just don't work - the Subaru thermostat is physically slightly longer, and you won't then get any strange overheating issues. And, oddly enough, the Subaru thermostat is usually cheaper than a spares company part.