Heater valve on AC equipped X1/9's

Dr.Jeff

Dr.Jeff

True Classic
Judging by the part listings found at vendor's sites, the factory equipped Air Conditioned X's use a different heater valve than the non-AC models. However I cannot find a listing or even a image for the AC version; only non-AC listings that specifically state not for AC cars. Checking for the "AC version" of the heat valve on the car it cannot be visualized (at least not without a LOT of disassembly), but feels like it does not have any of the 2-bolt flanges as seen on the non-AC valves.

Anyone have a part number, source listing, description, image, or rumor about what the AC equipped heater valve is?

Thanks
 
The AC heater valves are hard, if not impossible, to come by. Back in 2006, Kevin Cozzo posted a similar replacement valve he found that worked well in his 77X. I haven't found an example of a later car owner using this, but I will look some more.

Kevin's pictures are on Photobucket, so they may not be around for long. I will post his info from the Xweb 1.0 archives below and add the photots to Xweb V3 while we can:
Murray AC heater valve substitute 74627.jpg
Murray AC heater valve substitute 74627 installed.jpg

found this at Orielly's auto parts in Dallas. The vendor on this part is murray, and the part no is 74627 The original application listed sveral old chevy trucks, and also as "universal".The cable mounting bracket and control arm can be unscrewed and switched around, but it fit for me right outa the box. You'll probably have to modify the cable,and bring it around the right side of the heater box. I used an old manual choke cause all my original controls are wasted, and for me this is good, lots of extra cable.I imagine you could also move the new valve right up along the side of the heater box, if your cable isn't long enough. Also, I don't know if the AC expansion valve will be in the way, as mine is gone now. Hope this is useful info, Kevin Cozzo
Click to expand...
 
Here is MWB's page for the AC valve which is "out of stock", so it won't show on the regular pages of available items. If that is truly what it looks like, then the "substitute" valve above looks wrong since it is straight thru and the one shown on MWBs page has a 90 degree elbow.

I did a quick search of Amazon for "Four Seasons heater valve" (just one brand name I saw) and did find a few elbow style heater valves. Here is one example. I have no idea what it would take to make one work, since I have never had an X with AC.
 
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Thank you Jim and Larry. Those images of the stock valve (with 90 degree fittings) looks like what I feel when I reach behind the heater box. So I'm sure that is it. But as you guys say, they aren't to be found. In regard to using a suitable replacement, you also reminded me of a very old discussion here about heater valves where someone said something about using the common VW heater valve. But I do not know if that was for a AC application or not. Although I suppose it might have been because the VW valve is nothing like the non-AC Fiat valve. Here is an image:
vw-mk1-heater-valve-2711.jpg

You can find them everywhere super cheap. But as you can see it is also a straight through design. I might even have an extra VW valve left over from a prior build so I'll take a closer look. However just getting to that area on the X is nearly impossible (Larry knows). Although I will have to because I need to overhaul the AC system as well as replace the frozen heat valve. FUN!!

Dan, just saw your post as I was typing this. As far as I can tell the valve is controlled by a cable directly from the only lever on a AC control panel. The vacuum device is for the air flapper door I believe?? Larry, please confirm (I haven't gone that far into it yet).

Thanks everyone.
 
LarryC said:
I am thinking that I will rebuild that thread with the new Xweb capability.
Click to expand...

Larry, I just looked back at your AC rebuild thread again (had not viewed it in a long time). If possible please update your document with the missing photos, it will be extremely valuable when I redo mine. Thank you.
 
Thanks Ed. I just did a search and it looks like you must have bought the last remaining ones, because none were found. But I appreciate the tip. :)
 
While I was gathering up the necessary images to rebuild the ones that were lost to Photobucket, I uncovered a few more images of the AC heater valve that I took while rebuilding my AC system, including comparisons with one that is very close but not an exact replacement that I found on ebay a few years ago. With a little bit of fabrication it would work, except the diameters are a little small.
ranco_replacement.jpg
heater_valve_bottom.jpg
heater_valve_rear.jpg
heater_valve_top.jpg
 
Both of my X's have frozen heater valves which are of course different. My 87 with AC has a manual shutoff valve inline on the return line in the engine compartment so it has been that way for a long time.

I am considering going to a bypass valve in hopes of not having to revisit this issue every few years and to keep the coolant moving through the pipes. I know the X doesnt' suffer from the 124 problem of a heat problem at the back of the head, but hope that the constant flow would keep the valve from being so likely to fail. I also hope to use a plastic unit to get one more metal out of the loop in hopes of minimizing the galvanic reaction in the system.

There is this plastic 90 degree unit which is not bypass:

http://www.ebay.com/itm/Four-Seasons-74641-Heater-Valve/332009702931?_trkparms=aid=222007&algo=SIM.MBE&ao=2&asc=41376&meid=4da9982a543d4264b334f50ef9087ba7&pid=100005&rk=1&rkt=6&sd=131152116195&_trksid=p2047675.c100005.m1851

I would like to change both of my cars to one like this:

https://www.amazon.com/Old-Air-Products-25-1019-Operated/dp/B00LEUVDPG

I may buy a vacuum operated one (since they are so cheap) first to see how it will fit. Clearly this sort of solution will require some rework of the rubber hoses to make it all fit.
 

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My X came with a manual shutoff valve in the return line to the branch pipe. If your heater valve is stuck open (and not leaking) which seems to be the common failure mode, then adding a vacuum controlled heater valve in the engine bay is the easiest solution, IMO. I used an electric solenoid to switch the vacuum to the heater valve.

The downside is that the heat is on/off, there is no way to modulate the solenoid & bleed vacuum for partial heat. I haven't revisited that aspect as I really don't use the car in weather where I have the roof on & need to modulate it.

Ignore arrow in diagram, coolant flows the other way :)
X19_0807.jpg


Any EVAP valve will work for this, I used one from a Volvo

X19_0988.jpg


straight through or dogleg setup heater valves work

X19_0034.jpg


X19_0206.jpg
 
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I thought I had seen that on your car.

There is a proportional electric one that runs around 100 depending on who you buy it from. It comes standard with a rotary knob adjuster but I believe there is a linear rheostat that also works with it which would require some changes in the controller area. Advantage would be no longer having a cable negative would be another electronic widget that fails.

https://www.amazon.com/Old-Air-Products-50-1555-Electronic/dp/B00LEUV98M

I like the idea of it being in the engine compartment as it would reduce the heat being introduced into the cabin year round.

The vacuum unit for me would be as a test fitting piece as it is so much cheaper than the cabl actuated unit.
 
The heat valve on the '79 factory AC model is located directly by the heater core, on the floor behind the heater box. I did not realize the later models moved it to the engine bay. I like that; there is a LOT more access/room to install/modify a aftermarket valve/hose layout in the engine bay than there is behind the heater box. Not to mention accessibility for servicing. Opens up more possibilities for me to consider modifications. On a similar note, I never understood why the heater hose nipple from the water pipe (off the back of the water pump) is located on the driver's side (at least it is on the '79). This makes the hose path much longer than needed as it loops around and back to the passenger side before crossing the bulkhead.

I actually prefer a cable operated valve to a vacuum one...just personal preference. And I think for the sake of simplicity I will stay with a non-bypass type. Especially if a plastic valve is used and located in the engine bay. Again, just personal preference.

Please confirm for me, what is the size (diameter) of the heater hoses, and are all of them the same size? Also, has anyone determined the total length of hose needed to do a complete system replacement? Thanks.
 
Later models didn't move it. Hussein moved it. He moves everything and substitutes the finest parts of Bricks whenever he can...

An electrically controlled one in the engine bay would be ideal with the lower controller in the cabin replaced with a horizontal rheostat (also available from Old Air Products. This would keep the heat out of the passenger compartment except for when you want it. Something I am sure would be good in the land of Sin City being so close to Hell and all...

The heater supply line should go from the right side of the engine (from the head), over the snail engine mount and almost directly into the spare tire compartment where it then goes into the tunnel. It shouldn't loop around. The return should come directly up from the centerline of the car and then over the left end of the engine over the thermostat and into the return pipe to the water pump.
 
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I finally completed reloading of the images for the AC thread, the ones that Photobucket had stolen, wherein there are more pictures of the AC- heater valve and its location than you will ever need. Art Bayless seemed to think (back in the eighties) that the proper location was next to the heater even on AC versions. But all the manuals disagree. I wonder what that is all about? Maybe we don't want to know.
 
Thanks for clarifying about the valve location; after reading earlier comments I had the impression the newer models had it located by the engine.

And you are correct, anything to move heat away from the passenger compartment is beneficial when living IN hell (not CLOSE to it). I've gone so far as to think about relocating the radiator/AC condenser to the rear panel in the trunk. That would take the hot tubes away from under the floor and move all hot components to the back where the hot air won't get pulled back into the cabin.

Thanks Larry for doing that!
 
? is they're a link to the AC thread? I tried to print it a year (ish) ago and ran out of ink, then paper, then, then, etc, etc. (short version) it never got done.
 
Rod, Scroll up to the 4th entry in this thread, by Larry C.
Is that the one you are looking for? There were a few good discussions on it a couple years back so not sure which one you want.
 
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