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SOON 2 B 350
74 Posts
Discussion Starter #1
Living out around Phoenix, AZ can get pretty hot at times, so I needed to do something about my AC. I found my AC to be not so cold, so I did some investigation :)

My first thought was to go to the heater core. After taking a look, I found hot water to be continuously pumping through the heater core when not in use. Ive seen people place manual shut-off valves on the line pushing water into the heater core...but I see this as a good way to create leaks in the core, as people may tend to forget to open it every now and then.

Most cars have heater bypass valves operated by vacuum. Unlucky for us, we didn't get that option :(

So looking through the options, I found the perfect fit. A 1997 Ford Explorer V6 valve. It has the same outlets to fit our hoses, and keeps the same formation.

Here are the part numbers (I got mine at autozone, as it was the cheapest):

  • AC Delco 15-5829
  • Ford Motorcraft F87Z-18495-AA
  • Transpro Autozone 4 Seasons 74809
Ok, so on to the pictures (all were taken by me as well as the "flow one" - made it in photoshop :) )

This is basically what will be going on. Once you activate the MAX AC, it will utilize the vacuum for the inside air door to open and close the bypass valve. So you wont have to get out and pop the hood when its cold out!

Here are just some basic pictures of the valve:

This is a bad picture of the small shutoff valve that is activated by the vacuum:

This is where we will be tapping into the existing vacuum line (in which is only activated when MAX AC is turned on - as this is the door that allows it to re-circulate the interior air.

Remove vacuum hose:

Attach T fitting as shown. You will need to buy quite a bit of vacuum line if you want to go the route I did. The smaller piece was cut from the line I purchased earlier. Remove the grommet from the line going to the vacuum door (see pic above).

Take the grommet and place over the T fitting. Also take a few inches of hose and place over one side of the fitting. The long line that will go out to the engine compartment is on top.

Attach the line (that originally had the grommet on the end) to the small 2 inch line you placed on the fitting earlier. See below.

Re-attach grommet to canister:

Now this is how I routed it. I found it was the easiest way without drilling any holes. It was even easier because I was doing a sound system/speaker install at the same time lol. I basically took the line and ran it under the passenger speaker, in back of the receiver, and out the firewall through an existing grommet. Then I followed existing wires in the engine bay, all the way to the mounting location. See pics:

Here are pics of the bypass valve installed. The cuts are a bit ugly, but that is because I didn't have the right tool available (it worked).

The valve was mounted in the best place I could find...but use your discretion. I actually had to unmount the hoses from the fender clip in order to get it to mount properly. Everything is very stable.

Just plug the line in, and your done!

The valve works great, it shuts off the coolant with ease. And turns it back on command. The degrees difference was very noticeable. I dont have an exact number....but I wish I would have done it sooner.

There are obviously several ways to perform this mod...but this is the way I did it :)

4x4 v6 blazer
7,521 Posts
Nice, I think I might have to try this myself. Good job and I've never thought about this but it does indeed make sense.

1,461 Posts
Good job on the writeup man. In conjunction with this, i like to urge people to use a V.O.V aka variable orifice valve, you can pick one up for our truck at local parts store such as napa, i dont have the part number off hand but they can give you the correct one by app.

Look it up on yahoo if you dont know about them, they boost ac performance at idle or slow speeds quite a bit.

The htr core bypass mod, the vov valve, and some head shielding on my hvac box has helped this system work much better in my truck.... The condensors on our s-trucks are the weak link, they just dont remove enough heat, upgrading to a parrallel flow condensor would be a nice upgrade. (2nd gens already have those i believe)

1,063 Posts
whats AC?:D its 64* over here :rotf:
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