3rd Gen Tech: Colder AC in under 25

[wildcat]

This Bomb has been floating around the internet and the trucking industry for years. I got the idea to apply it to my truck from CBrahs, who also did a little write up here on it earlier this year.

My hope is this tech article may be a little more comprehensive, leaving little doubt, if any about what is needed, or how to do it. This modification was performed on an 2007 5.9L. With some variation, it should be adaptable to the 6.7L, and also other makes and models. For the purpose of this article, I’ll limit myself to considerations for the 5.9L only.

As the title suggests, this Bomb can be done for under $25.00 and 25 Minutes.

By completing this modification, you will lower your Air Conditioning air output temps about 10-15 degrees, by preventing coolant flow into the heater core.

The parts for the modification can be obtained at Home Depot, Lowes, Ace Hardware, or just about any other hardware store. What you will need to obtain is:
1- ¾” Ball Valve
2- 5/8” barb X ¾”NPT adapters
3- ¾” to 1 ¼” hose clamps
Roll of Teflon tape

I decided to only do one valve, placed into the supply line of the heater core. If appreciable “Heat soaking” occurs thru the coolant in the return line to the coolant in the heater core, I may later go back and install a second valve in the return line to isolate that from happening.

The tools required to perform the modification are quite simple also:

Standard screw driver, or socket and ratchet that fits your hose clamps.
Razor knife, or anything else that you can cut the hose with. (I used Tin snips)
12” crescent wrench, or the correct size wrench that fits your valve and adapters
A vise. (A second Crescent or wrench can be substituted for the vise.)

Here’s a couple pics of the parts I bought from Home Depot The total was $22.38



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Ok, Let’s get to work. The correct location for installation is in the 5/8” coolant supply line coming off the top of the head, on the passenger side. Here is a pic of me pointing to the proposed location of installation.


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The other side of the Heater core is the return side. It drops into a “T” that is supplying the liquid to liquid heat exchanger for the transmission. Here is a pic of that line, the screwdriver is pointing to the “T” location for reference.


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It is because of this “T” that no provision need be made for a bypass loop on the 5.9L.
The Heater core is effectively on its own loop, so the ball valve only affects flow to the heater.

The first step is to assemble the barb adapters and the valve. To do this, begin by wrapping the threads on the adapter with Teflon tape. Note the orientation of the fitting and the direction of the wrap. Wrapping it the wrong way will cause the tape to unravel, and may cause a leak. (I didn’t feel it was really necessary to wrap a brass on brass fitting, but with my luck, it would leak… !)


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Next, screw the barb adapters into the ball valve. If you use a vise to hold one end, while you tighten the other, you will want to put the fitting in the vise, NOT the valve. The wall thickness of the valve will not tolerate much clamping pressure without deforming, and causing a leak.
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When you are done, it should look like this


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The next step is to cut out a section of hose at our installation location. You may want to put a bath towel sized rag to catch the little bit of coolant that will come out. I removed 3” of hose from my supply line. Here is the section removed, compared to the valve and fittings I installed. From this pic you can determine how much needs to be removed by measuring your assembly, or “eyeballing” it, as I did.


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Next place the hose clamps over each end of hose, and install your valve. Be sure to orient your clamps so you can tighten them up.


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This is what my valve looked like after installation. It is shown in the closed (Summer) position. Start the truck and check for leaks with the valve both opened and closed. Top off the coolant level, if necessary.


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Questions and comments are always welcome!

[bobcat67]

Dang Bill that is awesome, i might actually have to try that modification though I don't live in Arizona

[wildcat]

Originally Posted by bobcat67 Dang Bill that is awesome, i might actually have to try that modification though I don't live in Arizona

Ty, If you use AC in Montana, you are a NANCY!!

[lukesdiesel]

Excellent Job

[wildcat]

Thanks, Luke!

[Redpatcher0481]

Nice mod

The only thing I would do is open that valve 2-3 times a month and let fresh coolant into the heater core. I would suspect letting that old coolant sit in the core for months would start to become corrosive and cause the core to fail come winter time. Like it used to do on the older cars.

[bobcat67]

Originally Posted by wildcat Ty, If you use AC in Montana, you are a NANCY!!

hey Bill you've obviously never been to Montana, not only do we get as hot as Arizona it also gets as cold as Alaska or colder I don't know, but yeah we have both extremes rather than just HOT

[wildcat]

ok... I take my "Nancy" comment back...

Now that I'm workin on "single" I might actually get to do some traveling...

[LOGANSTANFORTH]

been doing this for years on cars, it a good idea to do this on any vehicle, but like stated i would recommend opening the valve every once in a while and circulating the coolant so it dosent become stagnant and start to eat away at the heater core and cause a wet floorboard........

[wildcat]

How often do you think it should be open, Logan?

Redpatcher0481 thinks 2 or 3 times a month... I think that might be excessive, maybe once a month or once every 2 months... any thoughts?

[Begle1]

Not only does my first gen have one stock, but it's electric-over-vacuum controlled.

[Redpatcher0481]

Well I did the mod, and it turned out great. The only thing I did different was I found a 3/4" valve with 3/4" barbed ends (all one piece). I let the truck sit for awhile then went out there cut the hose, put on the hose clamps, and put the valve in. Worked like a charm. The valve cost me about $7.50 at Lowes. It took longer to wait for the truck to cool down enough than it did to put the valve in. I saw a 14* drop in temp coming out of the vent.

Thanks Wildcat

[wildcat]

Originally Posted by Redpatcher0481 Well I did the mod, and it turned out great. The only thing I did different was I found a 3/4" valve with 3/4" barbed ends (all one piece). I let the truck sit for awhile then went out there cut the hose, put on the hose clamps, and put the valve in. Worked like a charm. The valve cost me about $7.50 at Lowes. It took longer to wait for the truck to cool down enough than it did to put the valve in. I saw a 14* drop in temp coming out of the vent. Thanks Wildcat

NP man.

I too looked for an "All in one" valve. I couldn't find one with 5/8" barbed fittings. I figured if I was having trouble tracking down a 5/8" valve, or a 3/4 valve with 5/8" barbed fittings, others might also, so I would just cover the assembly of something that would work.

Did you have trouble getting the 5/8" hose over the 3/4" fittings?

Glad this helped you!

---AutoMerged DoublePost---

Originally Posted by Begle1 Not only does my first gen have one stock, but it's electric-over-vacuum controlled.

I "wonder" if it leaks by... Most of them do.. (By design, I think)

[LOGANSTANFORTH]

Originally Posted by wildcat How often do you think it should be open, Logan? Redpatcher0481 thinks 2 or 3 times a month... I think that might be excessive, maybe once a month or once every 2 months... any thoughts?

5,000 to 10,000 miles, about your typical diesel truck oil change.....on a newer truck i wouldnt worry, on something 10 years old i would worry more about it......and 14 degrees is a HUGE drop in air temp......what was the before and after temps and what was the outside air temp at the time you did the measuring.....

[diesel pap]

my cab tractor has a valve you close heater line off. i dont think new veh. close clear off by design. a ball valve will stop it dead. its got to help ac