Heater core bypass in 88-95' fullsize trucks?

Hey guys and gals,
Any of you bypassed the heater core during the summer months on an 88-95 fullsize truck to increase A/C performance? Those of you familiar with the
system know the heater core sits just below the A/C evaporator (heat rises, what the hell were they thinking!) and is always hot regardless of climate control settings.
I'm thinking <hoping rather> that this comprimises the A/C efficiency a tad, and bypassing the heater core altogether would result in increased A/C performance. So...............
1) Anyone try it? 2) Did it work? 3) Did you fabricate or buy an aftermarket bypass valve?
Thanks,
Doc
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valve and two short sections of pipe or tubing that match the valve and the inside diameter of one of the heater hoses. Cut the hose, insert the valve, and turn the water on or off as needed. Q.E.D
One word of caution, make sure that you have the right mix of water/antifreeze in the cooling system, because without hot water circulating through the heater core, in might freeze up from the A/C. You know that "heat rises" but also remember that cold sinks.
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Diamond Jim
"The Old Devil Dog"
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Jim, did it make a difference in A/C performance? If so, how much?
Doc

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A number of years ago I lived in the high desert of Calif., 29 palms to be exact. I had a black Chevy. I couldn't leave the windows down or even cracked during the day because of the dust and sand blowing around. And yes, I think the heater cutoff made a big difference. One problem was early in the morning it would be cold and by the middle of the day it would be hot.
I can't think of the name of the valve but they are a ball type valve. They open and close when the lever is rotated 90 and are rated as 300WOG. WOG stands for Water Or Gas. You can buy then with male or female threaded ends, plane male or female ends or just about any combination of ends you want. They only cost a few dollars, no where near as expensive as the OEM one the stealerships sell.
Now the more I think about it, I am pretty sure they are called ball valves.
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You can find a number of manual "heater control valves" at most any parts store. Various designs.
On Wed, 21 Apr 2004 02:38:23 GMT, "Diamond Jim"

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Elbert Clarke
elbert.clarke**@us.army.mil
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Better yet, go to the parts store. Get the cooling parts book and look for a valve made with the correct size connectors. Some vehicles used them. Cutoff valves that is.
And, no, I've never done this. I've always used the heater as an extra way to cool the engine off. Had some vehicles that would overheat because of the amount of boost I'd run on the turbo and I used the heater to keep me within limits.
"Either the engine overheats or we overheat" From "The Gumball Rally", the yellow camaro.

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I'd suggest a 4-core radiator....
~TLGM/KJ

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I've done that on my 92 Explorer. There is a valve ford sells and which also seems to appear quite regularly on ebay for this purpose and it shunts the water around in one position, and thru the core in the other. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item $73615832&category3545&sspagename=WDVW It's supposed to be vacuum operated to shunt it when you put it in MAX ac. I just move it manually twice a year (It wasn't original equipment).
As to whether it helps, it helps a lot. Temp readings of the air from my vents when the AC is off (controls set to vent position) show that even with the heat/cool level in the full cool position, all the heat buildup from the hot core raises the air temp by at least 5 degrees. Without turning the hot water off, there is no way to ever get truly cool air thru the system with the AC off. So you know that it's got the same hurdle when the AC is on. When you have the vehicle warmed up and then park it for an hour and that hot core heat soaks all the stuff around it you are just adding a huge load to the AC system. I can definitely tell it makes the AC air cooler in the middle of the summer.
-- Elbridge Gerry, of Massachusetts:
"What, sir, is the use of militia? It is to prevent the establishment of a standing army, the bane of liberty. . . Whenever Government means to invade the rights and liberties of the people, they always attempt to destroy the militia, in order to raise a standing army upon its ruins." -- Debate, U.S. House of Representatives, August 17, 1789
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wrote:

Thanks AZ, I'm gunna give her a whirl this weekend................
Doc
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Doc I made a setup for my 95 S10. Basically an "H" connector made with 1/2 brass pipe fitting and barbed connectors and a ball valve. The horizontal part of the "H" was a 1/4 orfice and the ball valve was on the inlet side of the heater core. When the ball valve was closed, coolant could circulate through the 1/4" orfice and return to the block. From what I could tell the heater core was the by-pass path for coolant when the t-stat was closed. If I shut off the heater inlet it looked like the coolant wouldn't circulate through the block until the stat opened. After this mouth-full, I really couldn't tell any appreciable difference. If you want to try something take a c-clamp and a couple pieces of wood and clamp the inlet hose shut to stop circulation. That should tell you if it's worthwhile If you have an accumulator I'd suggest wrapping with some extra insulation such as aluminum bubble wrap.
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