Hi all, back after a long stint away from old Subbies but have picked up an 88' EA82 wagon with 215k miles. It's a carbed model. Problem I have is the heater fogs up the windscreen when put on hot & defrost.

Doesn't seem to clear more than half the windscreen after about ten minutes of running at operating temp.

Is this normal or does it indicate more serious problems eg. coolant leaking in heater core?

Nice to be back in an old Subaru again!

Does the heater work well in the car?  And is the air blowing on the windshield hot?

Yeah, heaps of hot air coming out, all settings work correctly.

If it is equipped with A/C you should turn this on too. A/C acts as a dehumidifier which means the windscreen will clear in no time.

Could be your heater core has sprung a leak!

I have heard of pinhole leak in the heater core causing that, but there would be other symptoms. .. Check the fresh / recirculate air door. It is moved by vacuum.

Heater core is leaking. 

I would have to agree on the heater core leaking.............

Thanks for the advice - where should I go now? I've never done a heater core replacement but am keen to try. Are they something you can buy aftermarket? Am I better off pulling a JY one?

I have had the same problem and the "stop leak" worked.

 

Good luck,

Sam

I have not had one fail, so I probably would lean towards used. It is a project, you have to remove the dash board to get to the heater box, remove it, and disassemble it to get to the core.

I have not had one fail, so I probably would lean towards used. It is a project, you have to remove the dash board to get to the heater box, remove it, and disassemble it to get to the core.

 

Thanks Dave - I may ask a radiator shop and see if they can weld the hole. I've found a few instructions so will post back when I get a chance in the weekend to take out the dash. Cheers!

Do you have the vacuum line for the heater box hooked up? If not that's probably your problem. The recirculation vent is normally open and vacuum holds it closed. Had this problem in my car on the mountain, always fogged up but would roast you out of the car. Turned out it was recirculating the interior air. Should be a vacuum hose on the passenger side going through the firewall.

+1 on checking the vacuum line - same thing happened to me.  Fixed the problem in 10 seconds.