# 3rd Gen heater core and blend doors



## scottr (Oct 10, 2013)

Always good to learn from others mistakes right? Well, here's mine.
Most 3rd gen owners have heard about broken blend doors and how to fix them. My situation was one broken blend door and a slight hint of glycol smell when my core heated up. So, researched it, found a couple of options out there. I went with the billet Aluminum doors and a new heater core.
Lots of videos out there on what it takes to do this job. It's a good 3 hours or more to pull the entire dash, then remove the whole HCAV unit. That all went as smooth as those things do. Got the HVAC unit on the bench, split it open, replaced all 5 doors, re-assembled,,,, slipped the new heater core in. The disconcerting thing about these cores are, they use a swivel type supply & return tube, an o ring and then they stake the sides to hold it. This seems cheep and a real potential for leaking.








The tubes must be rotated to fit into the HVAC unit as they come parallel to ehch other in the box.
Put it all back together. Buttoned up the cab and ran the engine in the shop for 3-4 minutes. No leaks. Road test, engine temp came up and I smelled glycol.  Shined a light on the passenger floor and could see a big wet spot forming.. Booo. Back to the shop. No leaking fluid seen from the engine side of the firewall where the hose connections are, still dripping inside the cab. Flopped down in my chair and figured I had 6 hours ahead of me to take it all back apart to see a failed heated core. 
Before I did, I decided to do a quick test on the core. Put 40 psi on the core ( I know, way more than system pressure). 








The pressure held for 30 minutes ?? What gives?? To take it one step further, I hooked up a pump and circulated hot water in and out for 15 minutes, no leaks. Hmmmm. Here's where you learn from my hast. This is going to sound elementary I know, but, I re-used to hose clamps on the heater core, the spring type clamps. Ive done this before, no issues, if theres a problem, you typically see it right away. In this case, what was happening is, the hoses were pushed onto the tubes all the way against the fire wall padding and clamps in tight. When road testing, those spring clamps didn't hold tight and a small amount of glycol was pushing between the hose and tube and into the cab side of the firewall, hitting the back of the HVAC unit and running down onto the floor. A quart of glycol soaked into the carpet and foam is a mess to clean up. Tuff lesson, replace spring clamps, always. Like I said, sounds elementary, but I cut a corner and paid the price. To further ensure there was no glycol inside the HVAC unit, I drilled a small hole in the low point just to make sure it didn't drip, all good. So, didnt have to pull it all back a part, but spent hours cleaning glycol fromthe carpet / foam. 
Here's a couple shots of the disassembled dash and HVAC unit.


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## scottr (Oct 10, 2013)

All better :clapping: ( the old Dodge looks better next to my buddies Chieftain )


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## BUFF (Dec 24, 2009)

Dam you went deep..........


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## Randall Ave (Oct 29, 2014)

Wouldn't you like to grab the engineer and just put a cap in his -----


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## scottr (Oct 10, 2013)

Randall Ave said:


> Wouldn't you like to grab the engineer and just put a cap in his -----


Your not kidding. Heater core should be a 30 minuete job.


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## Plowin Dodge (Feb 11, 2009)

And they shouldn't have used plastic gears for the blend doors either Lol. Did that with my last truck I feel for yah


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## quigleysiding (Oct 3, 2009)

Just installed one in my sons dodge . Not fun .


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