Heater Core Flush Worked, Heat Came back...but Cold Again after 24 HOURS! (1 Viewer)

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Toronto, ON
Hey gang, well like the titles says, I flushed my heater core with CLR last night, and had it soak for a good 50 minutes, with one forward and one reverse flush and an air burp of the cooling system, and the cabin was absolutely heavenly in the 5f degree (-15c) Canadian Winter. But 24 hours later, as I headed out for a 40 minute trip to play simulator golf in town, I had almost zero heat. When I got to my destination my fingers and toes were blue from the cold and could not even feel the club in my hands, luckily my friend had spare chemical hand warmers for me on the way back.

....so what's the deal? I felt the heater core outlet hose after I parked it in the garage and it was lukewarm, pretty much the same as before I did the flush, while the inlet house was burned my fingers. Mind you, the outlet hose was very hot after the flush yesterday.

From my understanding, it seems like might be containments in the system that clogged the heater core again? So is a full cooling system flush in order here?

Thanks!
 
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I'd flush it backwards into a bucket. If you find a bunch of crud, that is probably your problem.
First though, check your heater valve and make sure it's WFO. Heck, disconnect it and tie it wide open. Especially if it's that cold!
Fingers and toes blue? No thank you sir!
 
Just be careful not to over pressurise the system when you flush. @Kernal warned me against this recently.

Maybe try adding some thermocure or Prestone flush solution to help get the crud out?
 
I'd flush it backwards into a bucket. If you find a bunch of crud, that is probably your problem.
First though, check your heater valve and make sure it's WFO. Heck, disconnect it and tie it wide open. Especially if it's that cold!
Fingers and toes blue? No thank you sir!
WFO? Wide Fricking Open LOL? It was WFO from yesterday, and some gunk did come out of the core after the flush yesterday, but whhhhy is it cold again! Could the rest of the cooling system be pushing dirt into the heater core and clogging it?
 
WFO? Wide Fricking Open LOL? It was WFO from yesterday, and some gunk did come out of the core after the flush yesterday, but whhhhy is it cold again! Could the rest of the cooling system be pushing dirt into the heater core and clogging it?
Are you sure you burped the system completely?
 
Are you sure you burped the system completely?
not 100% sure lol

the front was jacked up, I used the funnel method, and squeezed the upper rad hose a bunch....but didn't really see any bubbles come out. I haven't done this before, perhaps I need a deeper hill? Not many hills in my area!
 
I flushed my heater core with CLR last night, and had it soak for a good 50 minutes, with one forward and one reverse flush and an air burp of the cooling system
So you only flushed the heater core?

If your heater core was clogged, then the rest of the system is full of corrosion, too. You need to do a thorough flush of the entire cooling system. That's not going to be fun during a Canadian winter.

Also, don't be shocked if it ruins your water pump.
 
So you only flushed the heater core?

If your heater core was clogged, then the rest of the system is full of corrosion, too. You need to do a thorough flush of the entire cooling system. That's not going to be fun during a Canadian winter.

Also, don't be shocked if it ruins your water pump.
Not going to be fun at all….

What is it referring to? CLR?
 
Not going to be fun at all….

What is it referring to? CLR?
The "it" is the corrosion that's loosened by whatever you put in. CLR, Prestone, Thermocure, vinegar, whatever. The loose corrosion can abrade the water pump seals. It's definitely not guaranteed, but it's definitely a risk. Generally, it's a good idea to replace the water pump after doing a flush on a significantly blocked-up cooling system.

I've had decent results with several rounds of Prestone in a neglected Jeep 4.0. That was in the summer, though, when I could fill it with water and run it for five days. I think Prestone is citric acid. Thermocure sounds interesting, but their directions tell you to fully drain the coolant, put in Thermocure, and fill the rest with water. Definitely not an option for you with the weather so cold.

Obvious question: is your engine even getting up to temperature? Have you blocked off part of the radiator with cardboard? That's a pretty common hack in areas that get really cold.
 
Did a full coolant flush….heater core outlet hose is still lukewarm, pretty much no heat….WTF
 
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Hi Ch'all, So the heater is blowing pretty warm now after two flushes one with just distilled water and another with Prestone cleaner and distilled.

But I am still encountering problems with the heater control....

when the slider is pushed all the way to the right, wind sound changes from a low pitch hum to a higher pitch whine with more forceful air flow, if we compare this to my commuter car as I increase the temp, the low pitch hum would stay as the air gets hotter.

I should probably take a video , but the result is that at about 75% mark of the slider, I am getting hot air, not toasty but hot enough for winter, but if the slider was pushed 100% to the right, the air temperature drops to lukewarm (along with the sound thing mentioned above). So in the picture where the slider is, my AC would be blowing lukewarm air, but if I backed it off abit it would be hot....weird.

Would this be a problem with the blend door? Or something else that I am not aware of? It looks like to rectify the issue I would need to remove the panel trim which I've never done before.

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Possible issue with climate controller itself?

FSM says you can test temperature slider by checking resistance between terminals 1 and 2 with resistance reading approx 3.0Ω then step 2 would be check resistance of terminals 1 and 3 on connector B (18 pin connector). Resistance should go from 0 at cold selection to approx 3.0Ω at hot selection
 
Possible issue with climate controller itself?

FSM says you can test temperature slider by checking resistance between terminals 1 and 2 with resistance reading approx 3.0Ω then step 2 would be check resistance of terminals 1 and 3 on connector B (18 pin connector). Resistance should go from 0 at cold selection to approx 3.0Ω at hot selection

thanks ill crack open the FSM take a look...and as someone who slept through most of my high school science courses, this will be fun for me lol
 
I would disconnect the cable on the heater control valve and operate the valve manually from fully closed to fully open as your are testing. It possible that the heater control valve was replaced at some point with a part from a different model year that operate in a opposite direction.
 
I would disconnect the cable on the heater control valve and operate the valve manually from fully closed to fully open as your are testing. It possible that the heater control valve was replaced at some point with a part from a different model year that operate in a opposite direction.

yep its disconnected....woulds a crap HCV also cost issues? Pipes are both sides burns to the touch.
 

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