Forester heater

[frumpy]

I have a 2000 Forester. When I'm traveling on the highway, the heater has
plenty of hot air. But when I'm off the highway, the heater turns cool.
This is something that has happened in the last couple of weeks.

Any ideas what might be going on?

 

[Edward Hayes]

Low coolant or air in the heater core. purge air from the cooling system. ed

 

[frumpy]

Ed, I was a little low on coolant, which I added yesterday, so I think I
need to purge the air.

How do I purge?

 

[Edward Hayes]

By low on coolant I mean you must open the radiator cap when the engine is
cool. Don't trust the coolant reservoir unless your sure the
hose/connections don't leak. To purge try to park the car with the front at
least as high as the rear of the vehicle or higher if possible. Remove the
radiator cap and run the engine at idle until the top radiator hose is HOT.
Rev the engine a bit, say to 2-3000 rpm several times and observes air being
relived from the radiator. let the engine cool till you can touch the
radiator with your hand and top up the radiator and coolant reservoir. Cap
off the radiator and you should be good. Let us know if this solves the
problem. If it does not then you may have a plugged heater core which will
require a back-flush. eddie

 

[frumpy]

Eddie, I got the deal purged and added some more topped off the radiator and
coolant reservoir. Now I have good heat. Thanks for your advice. You are
the best.