The Heater Core thread

[lbhsbz]

Wife was complaining that no hot air on the passenger side...only the driver's side. I read a few threads about clogged cores, flushing with CLR, but I wanted to avoid that as It tends to dissolve aluminum. I'm also the guy that likes to know exactly what's happening and why....I tend to cut open lots of parts, new and used, to see what's going on. Hopefully I'll be able to figure out what's clogging the heater core and why, and how to unclog it without damage, and have photos to support it...taking one for the team I guess. I've already discovered several MUCH easier ways to replace the heater core...we'll get into that in a bit.

I tried to flush the core with a Hecat pulsed flush gun...probably ran 100 gallons through it, no real change, although I did get a bit of debris out.

I had to tear the dash out anyway to replace it (warranty...my old service manager just gave me the dash)...

With the pad off, and some of the ducting, same symptoms. All the servo motors seem to work fine through the various settings.

Here's a thermal image shot of the heater box where the core goes after warming it up..

Not a lot of red, and mostly cool on the passenger side. That explains things.

I proceeded to tear out the HVAC box...What a chore. I cut the tanks off of the core when I got it out...I'd say 70% of the tubes are clogged. The tubes are tiny...a .030" wire won't go through even the clean ones.

Here's now..

FML


More info later...phone is about dead

 

[AuSeeker]

Looking forward to the rest of this story!!

I know pulling everything out to get to the heater core is a BIG job, kudos to you for taking it on,
I HOPE you took this opportunity to also replace the AC evaporator as well since they aren't that expensive and
also known to go bad on some T4Rs.

 

[lbhsbz]

A new Evap core is going in as well...Denso unit.

 

[Whammy]

A new Evap core is going in as well...Denso unit.

I do not envy you in this project.

 

[lbhsbz]

Ok, parts finally came in. When I started the teardown...I was hoping it was a blend door issue or some such that I could resolve relatively easily...not so much. I figured the heater core, since this is not a rare beast, would be available within 2 days through the dealer....not so much....L.A. Depot had no stock.

Going back together now, I'll take some pics and follow up when it's done. Probably tomorrow as I have better things to do than this all night.

 

[theoutbackdream]

Crap man.. My friend had issues with his civic not heating at all, and I flushed the heater core backwards and forwards many times. After about the 3 time we went back to the backwards flow, TONS of debris just came out.. We got lucky..


But im surprised Toyota uses a tubing that small... It's like they want it to fail on us...

 

[lbhsbz]

But im surprised Toyota uses a tubing that small... It's like they want it to fail on us...

It only made it 200K miles...lol

As a Toyota owner, one might feel betrayed...as a domestic owner, one might feel thrilled.

"Conditioned" is the term at hand.

 

[Maineiac]

It only made it 200K miles...lol

As a Toyota owner, one might feel betrayed...as a domestic owner, one might feel thrilled.

"Conditioned" is the term at hand.

This!

 

[lbhsbz]

Ok, update...the car was finished up the weekend after all the parts came in.

I actually ran out of hardware (I think someone was in here before and forgot a few screws).

The A/C evap core was interesting...when I got it out, you could make out some coloration on the bottom...like a water line almost, but not really. I imagine it had to do with condensation collecting around the bottom and dirt/crap collecting and uneven airflow. If I drug my finger over the fins, as soon as I got past the discolored area on the bottom, the fins just disintegrated. It wasn't leaking, but probably would have been soon.

After seeing the degradation of the EVAP core, it was probably more important than the heater core (heater core was just clogged up, no danger of leaking at this point). In light of this, I'll skip my borderline hack ideas for changing the heater core by itself the easy way. Tear everything down and do it right.