Don't you just hate it when summer gets here and it's hot out and your vents blow 120F air and all you want to do is ride with the top down and not sweat.

Or, maybe you think your A/C sucks worse than a Chevy Cruze.

There have been a few heater core mods that solve the problem, but most require some effort to reverse and usually leave your heater core isolated without coolant.

Thinking about this, I went looking for a heater valve that could be easily switched and would not leave the heater core "dry".

I found this Everco valve with 3/4" ports all around, matching the heater core nipples and one of the supply lines. The other one is 5/8"; can't have it all. As I remember it is from some older version of a Ranger pick-up.

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You will need a 3/4" to 5/8" hose barb reducer.

This one comes with a vacuum cylinder. I toyed with an electric vacuum valve and a dash switch, but ended up going lazy and simple, not using it. The over center spring means I can change the flow in a couple of seconds after I open the hood. It is pictured in the "heat" position.

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The last picture shows the hose loop I used. The other OEM molded hose might have worked, had I not had to cut it to get it off. I did not take time to hunt another molded hose that might also work. I want to see how well this trick works. That hose might get redone, soon.

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Be careful not to let a hose touch the A/C line.

A cereal bowl will catch the coolant that leaks out and fit below the hoses.

Go ahead and remove the shock tower brace, it's less trouble than working around it.

Normally, the engine coolant circulates through the heater core, that's in the dash right beside the A/C evaporator. So, it heats the the duct work and if the flapper valve that isolates the air path through the heater core doesn't shut tightly (lots of NCs, like mine, don't) you get hot air through the vents, whether you want it or not. That extra hot air reduces cooling capacity of the A/C system. Extending the time it takes the A/C to cool the car.

This valve loops the coolant back into the cooling system just the same way it normally flows without passing through the heater core, keeping the heat out of the dash and ducts. The cooling capacity is down right surprising, now.

This could be done other ways, like pulling the coolant lines off the heater core and splicing them together. That would leave the heater core open and partially dry, encouraging corrosion and failure. Using this valve keeps pressurized coolant in the heater core affording it corrosion protection. It is very quickly switched between open and closed to heat, or not. And, if I had not been so lazy, I could have installed a switch in the dash. 

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