There was a recall on this part. Call your local dealer

 

as others have said, air in the system is your most likely culprit.

give it a few days and watch your coolant level and temp.

 

A) This thread is old and the issue at hand has been solved.

B) If you read the OP you'd see that the TSB is not in question whatsoever. My issue was due to the fact that I had a thermostat that opened at 143*F, and thus was too cold for the heater to blow hot air.

 

See above.

 

lol people bumpin it up glad you got it resolved.

 

No worries! Thank ya much.

 

Now that a resolution has been posted. It may stay buried. Unless a thankful soul wants to reply with a thank you for helping solve their problem.

 

Thanks for your reply.

 

Anytime, part'na.

 

fyi this did turn out to be the thermostat for me, to the surprise of my local shop. car's coolant temp reading rises so much slower now (used to be very quick with the old thermostat), and i actually get heat.

 

I was looking through the Service Manual instructions for changing the thermostat. I don't remember removing a radiator hose or completely draining the the cooling system. You do need to drain sufficient coolant to lower the coolant level to below the thermostat housing.

 

I've gone through a couple of thermostats personally. I have no idea why other than bad luck. Luckily replacement is quite simple. Drain some coolant, pop off the upper radiator hose by the thermostat housing, remove the 3 bolts and bam! remove the old tstat. Clocking it was something that was in question and I never did figure out how the bleeder should be oriented. If you are looking directly at it I had it at 6 o clock and I havent had any issues. Good luck!

 

Had the same issues with my 05 legacy and it was air pockets in the coolant system.

 

I just got out of garage tonight after replacing the thermostat. My Evo has always had a great heater. Not this year. I still had the old thermostat that came in it from the factory so back in it went. We'll see.

 

The old thermostat had been in the car for 60K and the rubber seals were hard. But it was what I had. The thermostat I took out of the car was closed completely - no air gap. Also, no other visual sign of failure. But now that the junker thermostat is back in the car I have heat, which is good since temperatures are supposed to fall below zero this weekend.

Without boiling the two thermostats together I conclude the thermostat that acted up had started opening early (this isn't the first time I have encountered this). How this can happen with a wax pellet design is beyond my understanding. The melting point of the wax would have to change.