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Discussion Starter · #1 ·
Hello all -

Newbie here with a question. We've had our 2007 Dodge Grand Caravan 3.3 for about a year and a half. It's been pretty good so far, but I noticed something odd the other day.

I was unloading the van after a day trip, and was removing a plastic container of snacks that had been sitting in the recessed area on the R side of 3rd row. The container was quite hot, and so was the entire area.

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The next day I removed the plastic panel and found that the heat was coming from the hoses to the rear heater core.

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I presume that rear heat/AC is regulated by a blend-air door, and that therefore coolant flows through the heater hoses all the time - in which case it appears this excess heat is to be expected.

Is this normal? I had hoped there was a mechanical valve somewhere to cut off the flow of coolant when the rear heater is not being used, but no such luck. The rear AC works fine, but is largely negated by the heat coming off the heater hoses.

As a temporary solution, I put clamps on the rubber hoses under the van. This has reduced the flow enough that the amount of heat being released into the interior is much less. I plan to remove them c. late October, at which point the excess heat will be appreciated.

However, it's sort of a hokey solution. Is the situation (before my 'fix') normal, or is something wrong with the rear heat?

Thanks in advance!
 

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There are no flow control valves, coolant is always flowing. Air flow control doors control heat flow.
Are your overhead controls for rear heat turned off? Front as well.
Shut the total system off and see what happens. A door actuator may be acting up.
There is a calibration procedure:
 
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Drivin' Maniac
2002 Grand Caravan ES 3.8L
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There are no flow control valves, coolant is always flowing.
X2 That is why the vans take a longer-than-average time to warm up in winter.

Also, the rear A/C will always run the compressor unless you switch it OFF. (In hot weather, though, the rear air DOES help keep the entire van 'comfy')
 

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Discussion Starter · #6 ·
Are you showing us AC lines or heater hose? If AC, they will not be hot if AC is off. If heater, coolant runs all the time thru the hoses, and as Jeepman said, they can be blocked off.
I thought initially they were AC lines, but they are definitely heater lines.

It sounds like it's normal for them to radiate a lot of heat, but I think it's a poor design. The passenger side near the back gets very hot.

If there were a hose I could plumb into easily (i.e. under the hood), I would install a valve I could switch over twice a year. Unfortunately it looks difficult to do so without also affecting the front heat.

My temporary fix (clamps compressing the hoses underneath to restrict flow to the rear heater core) may have to do.
 

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If you don't want rear heat ever, you can loop the hose underneath, near the front.
 

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Discussion Starter · #8 ·
If you don't want rear heat ever, you can loop the hose underneath, near the front.
That's the thing about living here - I certainly don't want the rear-heater hoses radiating heat into the passenger compartment when it's +35 C (95 F) here, but would very much appreciate rear heat when it's -35 C (-31 F). So I suppose I could do a seasonal changeover, but it would be a big hassle - a valve would be much easier.
 

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That could probably be rigged up to atleast cut down on the flow or even bypass the flow.
The only thing is that they don't have control valves on them in order to keep from getting plugged up when not in use, or keeps the system simpler? Helps with cooling of the engine.
 

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Discussion Starter · #10 ·
That could probably be rigged up to at least cut down on the flow or even bypass the flow.
The only thing is that they don't have control valves on them in order to keep from getting plugged up when not in use, or keeps the system simpler? Helps with cooling of the engine.
Or can we just blame Robert McNamara, and his cost-control strategy at Ford in the 1950s?

I paraphrase, but in essence:
"If we build a million cars and can save a dime per car, that's a hundred thousand dollars, tax-free. Around here we'll kill for a dollar per car!"

I'm guessing a blend-air door is cheaper than a remotely-controlled valve.
 
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