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Unicorn Driver · 12-05-2021, 01:38 PM

Hi,

My 2012 Wranglers heater is blowing cold, IR thermometer is showing 70f at the vent, think I read it should be 130f.

Local Jeep dealer went straight to replacing the heater core for 1300$, my Jeep buddy told me to ask them for a flush.

What do folks think? I thought it might have been a blend door.

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BirchyBoy · 12-05-2021, 01:53 PM

That year is known for issues with casting sand. You can try a flush but it may not help.

khocke · 12-05-2021, 02:49 PM

Owners and indies have a “shortcut” to replace the core which involves cutting out (and later bolting or welding it back in) a dashboard support brace. Obviously a dealer won’t do this, so the $1300 quote is because all the labor involved with removing seats and everything inside forward of that. The core itself is only like $60!
There are a number of youtubes and Jeep forum instructions out there. Google “jk wrangler heater core replacement shortcut” (key word is ‘shortcut’) and you’ll see the options.

As mentioned sand is sometimes a cause, as is mixing HOAT and OAT coolants, which turns antifreeze to jelly. Our ‘12s use HOAT, in ‘13 they switched to OAT.

Green D · 12-05-2021, 05:39 PM

Quote:

Originally Posted by khocke

Owners and indies have a “shortcut” to replace the core which involves cutting out (and later bolting or welding it back in) a dashboard support brace. Obviously a dealer won’t do this, so the $1300 quote is because all the labor involved with removing seats and everything inside forward of that. The core itself is only like $60!
There are a number of youtubes and Jeep forum instructions out there. Google “jk wrangler heater core replacement shortcut” (key word is ‘shortcut’) and you’ll see the options.

As mentioned sand is sometimes a cause, as is mixing HOAT and OAT coolants, which turns antifreeze to jelly. Our ‘12s use HOAT, in ‘13 they switched to OAT.

Did this shortcut fix on ours pretty easy and hot now.

Unicorn Driver · 12-06-2021, 08:14 AM

Thanks folks,

Will report back

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zmotorsports · 12-07-2021, 12:37 PM

A couple of suggestions.

You can use an IR gun to check the Delta T, difference between the hose going in to the heater core vs. coming out of the heater core from the engine bay. Try to shoot the hose as close to the nipple from the heater core coming through the firewall as possible. It should be relatively close in temperature but much more than about a 15-20 degree variation will indicate there is a blockage in the heater core.

The FCA's (Chrysler/Jeep) are known for HVAC door actuator issues, blend, recirculation and mode doors. The blend door actuator is located under the dash near the driver's knee. This controls the temperature coming out of the vents. Usually they fail with a clicking sound as the small gear inside the actuator breaks but they can also fail stuck open or closed. By pulling that lower panel under the steering column and looking behind the duct work you should be able to see the arm and lever moving as you change temperature settings on the dash.

STRich · 12-08-2021, 08:10 AM

Pull your catch can/overflow tank and dump out the contents and see if you get a blob of casting sand that looks like liver.

If so, you will need to have some frost plugs knocked out and some rather vigorous flushing going on. We have recovered every heater core by back flushing them with some water and compressed air.

Good luck!