Since it is summer time and we do not yet have a thread up on this subject I thought I would start one. The main benefit of doing this mod is that you get colder air out of the AC as you are not trying to cool down air that has been heated up by the heater core. You are simply shutting off the flow or coolant to the heater core using a valve controlled by a vacuum source. I will also put this in the Library to save once we get a good thread completed on it.
There are a few variations of this that give you some options that we can lay out in this thread. A basic set of directions is:
I have instructions that I came across some time ago. I do not know where I got them but here they are:
A/C heater core shutoff mod
This mod will stop the flow of hot water through the heater core when the AC controls are in the MAX setting and the OFF position providing cooler temps and preventing the hot pocket of air down by your feet. I went to NAPA and asked for the 'hot water shut off valve' from a 1990 Ford Ranger with a 4.0 V-6, I also got 4 - 5/8 hose clamps, a couple feet of 1/8" vacuum line and a 1/8" plastic "T" for the vacuum line. To begin the install loosen the cap on the radiator overfill to remove pressure from the system (do this while the engine is cool). On the passenger side of the engine compartment there are two 5/8" hoses that come from the firewall and continue to the engine, these are the heater hoses. Cut the hose closest to the drivers side (It doesn't really matter where, I did mine about 6 inches after the firewall). Then holding the 'shut off valve' with the vacuum controller towards the passenger side install the portion of the heater hose coming from the cab to the top left nipple on the 'shut off valve'. Tighten the clamp. Install the portion of the heater hose coming from the engine to the top right nipple and tighten the clamp. Next cut the heater hose closest to the pass side in the same location as the previous. Install the portion coming from the cab on the lower left nipple, tighten the clamp. Now install the portion going to the engine on the lower right and tighten the clamp. Measure out how much of the 1/8" vacuum line you need to reach from the bottom of the vacuum canister on the shut off valve to the white vacuum line on the pass side that goes to the vacuum operated door underneath the pass side cowl. Cut that white vacuum line and splice in the 1/8" plastic "T". Then run the 1/8" vacuum line you measured out from that plastic "T" to the nipple on the bottom of the vacuum canister on the shut off valve. It sounds more complicated than it is. Once you do it the job will seem real simple.
I did mine a little differently because I wanted to shut off the flow of coolant to the heater core in Max AC, AC and Vent. To accomplish that I tapped into the blue line under the glovebox inside the cab for the vacuum source. I have found that lets the vent position be much more useful the air temp from vent is not getting heated by the heater core. The only downside is that I have to unplug the vac line in the winter so that I can get heat in the vent position. Floor and defrost do work normally with the vac line connected.
if you just block the hose arnt you blocking the return flow to the head?[/quote]
I was concerned about that too. The heater hose does look to be the return flow path from the passenger side of motor from looking the coolant flow diagram.
Basically from what I have figured from looking at a pump and a front cover is that the water pump pushes coolant into the block from the front cover. From there it flow up into the heads and then back down. On the drivers side it flows through a passageway on the block and back into the front cover. On the passenger side instead of going back through the block to the front cover it goes from the head out to the heater core, back from the heater core to the hose on top of the water pump.
I had the same concerns as you did and many years ago I put on a 4 port valve just to be sure. It has always worked fine and I have had zero issues with it.
The red arrows show the true coolant path in this photo to the best my knowledge. As the hose on the top of the water pump is in the same chamber as the inlet. I also think I tested this when I installed my valve. The diagram fails to show the tee and the line going to the bottom of the radiator right next to the hose going from the radiator outlet.
I made an additional discovery when messing around installing a coolant filter. On MY TRUCK the fitting to the radiator where that half inch line attaches has a restriction orfice in it that less then a 1/8" in diameter. I looked at the back of a front front cover and it looks to me like the heater hose path is the 100% return flow passenger side of the head unless there is a passage way in the block that allows coolant flow from side of the motor to the other that I do not know about. If there is not a cross block passageway blocking the heater hose on MY truck appears to mean that the passenger side coolant flow has to travel through that orfice at the radiator. Does anyone know if there is a cross block coolant passage?
Ive read of doing this since I got by truck a few years ago but my a/c is so cold now (38 degrees with it 90 outside) I cant see a reason to do it personally on my truck. Heck if anything I bet my a/c is cooling the engine some
Does seem like ford had a reason to keep it flowing though and the return flow you mentioned could be it. I dont remember how the hoses route thru it right off the bat.
On my truck I would do the mod for the sake of how much better it makes using the vent setting if nothing else. It makes vent useful on a 60-70 deg day instead of a heat function.
Another reason to block off the heater core, besides allowing the A/C to cool unheated air, is so that you can use the 'vent' position in the fall and spring and get cool outside air so that you don't have to run the A/C. I used to take a C clamp and squeeze shut the line to the heater core, which worked fine, but if it was hot in the daytime and cool at night I was under the hood more times than I cared for.
In a galaxy far away and a website from another time a guy going by hutchinaugusta came up with a fully automatic method of shutting off the flow to the heater core...read the thread here (scroll down to ExcursionPSD - post number 6) and then see Hutch's pictures here. Hutch had a very good description of how he did it, but I was unable to find it...:shrug:...maybe someone else can do a better search over there...
Tim
PS...I'm gonna have to learn to type faster! Tom, and others, beat me by 6 minutes...
I would guess it takes 5-10 degrees off the AC setting and maybe 20 on vent. It is a easy to do mod that works. I used to hate the vent setting unless it was cold but now you can use it at times on those inbetween days when before it meant all the noise of windows down or running the AC. I hope some other will post up results as well.
Tim, it's sad that all the good information from back in the day at that site is basically lost as it cannot be found. FYI I am surely not taking credit for this mod just sharing some info from the old days for the newbies. I might have been the one to figure out the blue line is about it.
I sure agree with that! Your post reminded me of the old stuff and I went over there looking...kind of a blast from the past...and yeah, lots of info for folks just getting started...you're to be commended!:bowfast:
The use of the Early 90's Ranger V-6 valve allows bypassing the heater line back to the engine. I never had a valve failure and its been in there since the mod was first publicized back when.
I did not cut the vacuum line to insert the plastic tee. I just took the stock line and put the tee into the end, put a short piece of the new tubing on the tee and hooked it to the new valve, and ran new tubing back to the original valve. There's a picture of it in my sig photos.
This is mine. The hose on the right where you can read the words Gates goes to the hose that comes off the head. The other hose goes to the top of the water pump. You can see the flow arrow in the picture.
A closer look. Since I used the blue line in the winter I just pull the vacuum line off the actuator and plug it into the rod that show in the picture. Then it all works just like the factory made it. I like these valves that are more metal. I think the plastic ones look like they might break. A two port valve could also be used here. I just chose this back when I did this mod.
I used the blue line under the dash which cut off the flow of coolant in vent, AC, max AC. I unplugged the clear looking connector from the actuator and put that on a tee. I then used vacuum to run from the actuator to my valve under the hood. The tee is spliced into that line. I did not have to cut anything by doing it that way.
If you really want to get fancy beyond Allen and his hose pinchoff pliers Dieselsite has a electric vacuum control so that you can control your heater hose valve at the touch of a switch. Cold Rush- Upgrade to 6.0L and 7.3L Max That just stuff Allen under the hood like trunk monkey.
Just did mine last weekend and it seemed to help. Ford place ordered wrong valve for me so I ran to parts store and jst picked that was the correct size. I dont even know what it was for. One post said to use a 1/8 tee on white hose under glovebox for vac line but the 1/8 tee didnt fit very well. I have it half arse stuck together for now and it does work but i need to find a smaller T i think
I used the blue line under the dash which cut off the flow of coolant in vent, AC, max AC. I unplugged the clear looking connector from the actuator and put that on a tee. I then used vacuum to run from the actuator to my valve under the hood. The tee is spliced into that line. I did not have to cut anything by doing it that way.
I went thru 2 of these from diesel site and gave up. My problem was following their directions, it would suck the diaphram clear out of the housing and off the rotating pin.
They did take care of me on a replacement, but then the second one broke the same way so i gave up.
I'm going to try the 90 ford model and see if its designed different.
Its very easy to hook up, so not really sure how I could have screwed it up. just glad I hadn't cut the hoses before I tried the valve to see how it worked.
very simple process, but either mine had WAY to much vacuum or I was doing something wrong.
please let us know how yours turns out.
We had a few failures back when we used the plastic valves about 4-5 years ago. We replaced every one.
We don't make some secret valve that only we have. The plastic ones, sold at every auto parts store in America, sold under the 4-Seasons brand, had a failure rate of 7-8%. When I called to complain, they said that rate is way under their acceptable rate. It wasn't good for us. So we dropped the product line for about 4 months while we looked for a good alternative.
We then found the metal valve we have now and have not had one complaint, not one failure, nor one return in at least 4-5 years (none since the new metal valves anyway). I sell hundreds per year of these kits. Don’t know what else to say. :shrug:
The valve I use is an OEM Ford part. There are MILLIONS out there.
I had the metal valve, and it was the plastic flapper valve inside that kept snapping off. It almost seemed like the vacuum is pulling way to much.
Service was great, exchanged the first time with no questions asked.
Any ideas on what I could have been doing wrong? I'd sure like to have made it work for sure. There is only one line under hood to hook it to, correct?
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