2007 Dodge Grand Caravan - Rear AC Line Very Hot

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We did a road trip with the little ones yesterday, and had the AC running pretty much the entire time. My wife and I were in the front, and found the AC to be working fine.

When I was cleaning out the van at the end of the day, I noticed that a little container of snacks that had been sitting in a recess on the R side of the 3rd row was quite hot. Wha ...???

I snooped around and discovered the plastic in that entire area was quite hot.

I felt the tires and rotors on all four corners, and although the tires were warm and the rotors hot (this was within five or 10 minutes after we got home), they were all about the same - so evidently the heat was not radiating upward from a sticky brake on that corner.

I started pulling things apart, and found that the one AC hose I could access easily was very hot.

My wife is out with the van right now, but I hope to do a bit more investigation later.

I know almost nothing about AC, and would appreciate any insights any of you have. There are lots of posts online about the rear AC blowing hot (while the front AC is fine), but I've found nothing specifically about the hose being hot.

Thanks!

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Number_35

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I can't tell by the pic but are you sure that's not a heater line?
Chris, I was hoping you'd see this. I assumed it was AC, due to the type of fitting.

I hope you're right! Then it's just a case of figuring out how to shut off flow of coolant through the line.

I'll investigate some more.
 
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I would think thing there was a water valve in the engine compartment preventing hot water from circulating to the rear core. One a/c line going to the evaporator is going to be cold, and the other one hot. Just like in the front.
 
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Probably a heater line and not one manufacturer I know of still uses valves. It is way easier and in the long run better to have a constant flow through the cores and just meter the air across them. This prevents stagnant flow from plugging up the core.
 
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Chris, I was hoping you'd see this. I assumed it was AC, due to the type of fitting.

I hope you're right! Then it's just a case of figuring out how to shut off flow of coolant through the line.

I'll investigate some more.
Run the thing. There will be a small ac line that's warm and a big one thats cold. Then 2 heater ones.
 

Number_35

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Confirmed, that is a heater core hose for the rear and should have another beneath it.

View attachment 111783
I can't tell by the pic but are you sure that's not a heater line?
Yup, they were heater lines, not AC!

I would think thing there was a water valve in the engine compartment preventing hot water from circulating to the rear core. One a/c line going to the evaporator is going to be cold, and the other one hot. Just like in the front.
That's what I was hoping for, but no.

Probably a heater line and not one manufacturer I know of still uses valves. It is way easier and in the long run better to have a constant flow through the cores and just meter the air across them. This prevents stagnant flow from plugging up the core.
Agreed, the mechanical valves have been replaced by blend-air doors.

But, and this is what I don't get, surely there shouldn't be so much heat transferred into the passenger compartment. But I don't see any way around it if there's constant coolant flow through those lines.

This is the cubby where the snacks got so hot:

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And this is my low-budget solution, for now. Where the heater lines transition to rubber hose under the van, I installed one of these clamps on each line, so as to restrict the flow of coolant through the rear heater core. (I wasn't sure which line was supply and which was return, so did them both.) The storage niche inside now gets warm but not hot.

If I don't do something more permanent before then, I plan to remove these around mid-October, when extra cabin heat becomes a benefit.

One YouTuber, rather than replace the rusted-out coolant pipes on his van, bypassed them in the engine compartment. I might do that ultimately.

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Could be the blend door not sealing 100% as when new and not running the rear A/C.

My father's van had painted steel lines underneath the car that had multiple pin holes. I bypassed them in the front with little effort. It will take the cabin longer to heat up in the winter but otherwise no effect on anything.
 

Number_35

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Could be the blend door not sealing 100% as when new and not running the rear A/C.

My father's van had painted steel lines underneath the car that had multiple pin holes. I bypassed them in the front with little effort. It will take the cabin longer to heat up in the winter but otherwise no effect on anything.
Thanks, I'm considering doing that.
 
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