NC Tom Posted February 19, 2023 Share Posted February 19, 2023 Just want to know if I knocked something loose, or is this just another strange, unneeded part under the hood. I noticed this canister, filter, alien tech while shoving hoses around trying to get the valve cover off. Don't see an open hose, so maybe it's nothing. Thoughts? Link to comment Share on other sites More sharing options...
87MJTIM Posted February 19, 2023 Share Posted February 19, 2023 Looks like the heater control vacuum switch. Link to comment Share on other sites More sharing options...
Armyvet25 Posted February 20, 2023 Share Posted February 20, 2023 exactly what it is Link to comment Share on other sites More sharing options...
Big_Mark Posted February 20, 2023 Share Posted February 20, 2023 20 minutes ago, Armyvet25 said: exactly what it is It's a vacuum driven "servo" that opens and closes the flow of hot coolant to the heater core when you move the heat/air/etc. control in the cab. My money says nothing happens when he moves his lever Link to comment Share on other sites More sharing options...
pizzaman09 Posted February 20, 2023 Share Posted February 20, 2023 My factory plastic valve actually exploded when I was working under the hood and I got some darn hot coolant on me. A new one was worth while, picked up at Advanced Auto in a day. Link to comment Share on other sites More sharing options...
NC Tom Posted February 20, 2023 Author Share Posted February 20, 2023 2 hours ago, Big_Mark said: It's a vacuum driven "servo" that opens and closes the flow of hot coolant to the heater core when you move the heat/air/etc. control in the cab. My money says nothing happens when he moves his lever Okay. Is there a diagram around that I can use to reconnect? Link to comment Share on other sites More sharing options...
cruiser54 Posted February 20, 2023 Share Posted February 20, 2023 I'm not so sure that's the HCV. HCV is mounted further forward and higher. Follow the pinkish plastic vacuum line. Link to comment Share on other sites More sharing options...
NC Tom Posted February 20, 2023 Author Share Posted February 20, 2023 1 hour ago, cruiser54 said: I'm not so sure that's the HCV. HCV is mounted further forward and higher. Follow the pinkish plastic vacuum line. Will do! Link to comment Share on other sites More sharing options...
Armyvet25 Posted February 20, 2023 Share Posted February 20, 2023 I'll take a picture of mine today for visual reference, if it is the HCV it normally has a lever that open/closes an inline fitting of your heater hose going into the core, and like he said, the pinkish vacuum line operates it when you adjust your cab selector from hot/cold. Link to comment Share on other sites More sharing options...
NC Tom Posted February 20, 2023 Author Share Posted February 20, 2023 16 minutes ago, Armyvet25 said: I'll take a picture of mine today for visual reference, if it is the HCV it normally has a lever that open/closes an inline fitting of your heater hose going into the core, and like he said, the pinkish vacuum line operates it when you adjust your cab selector from hot/cold. That would be great! Thanks! Link to comment Share on other sites More sharing options...
jpnjake Posted February 20, 2023 Share Posted February 20, 2023 This is the HCV I have in my chief, note it’s not running so not everything is hooked up, including the vacuum line. But without it connected to vacuum you shouldn’t have heat Link to comment Share on other sites More sharing options...
Armyvet25 Posted February 20, 2023 Share Posted February 20, 2023 Link to comment Share on other sites More sharing options...
Armyvet25 Posted February 20, 2023 Share Posted February 20, 2023 Here's a nice replacement HCV replacement Link to comment Share on other sites More sharing options...
Big_Mark Posted February 20, 2023 Share Posted February 20, 2023 1 hour ago, Armyvet25 said: Here's a nice replacement HCV replacement That's the widget right there! If mine wasn't working I'd buy this one Link to comment Share on other sites More sharing options...
Armyvet25 Posted February 20, 2023 Share Posted February 20, 2023 1 minute ago, Big_Mark said: That's the widget right there! If mine wasn't working I'd buy this one for 10 bucks I'd buy one anyway and put it on a shelf Link to comment Share on other sites More sharing options...
gogmorgo Posted February 20, 2023 Share Posted February 20, 2023 If you do that it’ll last so long you’ll never remember where you put it. If it does fail just bypass it and order another if you really want, or just leave it bypassed. Link to comment Share on other sites More sharing options...
NC Tom Posted February 20, 2023 Author Share Posted February 20, 2023 5 minutes ago, gogmorgo said: If you do that it’ll last so long you’ll never remember where you put it. If it does fail just bypass it and order another if you really want, or just leave it bypassed. You are right. If I didn't install it then I would have no idea where I put it! It's rainy here so I have not been out to check it. Just how many connections can be "bypassed" on an MJ? Seems like most of them. 😆 Link to comment Share on other sites More sharing options...
Armyvet25 Posted February 20, 2023 Share Posted February 20, 2023 42 minutes ago, gogmorgo said: If you do that it’ll last so long you’ll never remember where you put it. If it does fail just bypass it and order another if you really want, or just leave it bypassed. mines rusty as heck, might still be working but I'm replacing anyway now that I'm acutely aware of it's condition Link to comment Share on other sites More sharing options...
AZJeff Posted February 20, 2023 Share Posted February 20, 2023 I am surprised anyone is really suggesting replacing that stupid thing. The later XJ's eliminated this troublesome piece, and there were no adverse behaviors caused by that action. I would just ditch the valve, and replace the heater hoses with the more modern routing that the later XJ's employed, and never look back. Link to comment Share on other sites More sharing options...
jpnjake Posted February 20, 2023 Share Posted February 20, 2023 15 hours ago, AZJeff said: I am surprised anyone is really suggesting replacing that stupid thing. The later XJ's eliminated this troublesome piece, and there were no adverse behaviors caused by that action. I would just ditch the valve, and replace the heater hoses with the more modern routing that the later XJ's employed, and never look back. I have this done on my Comanche, the only thing I’d say the valve is good for is my passenger complained about the heat from the dash without the heat on in the summer, the late xj’s don’t have that problem since the dash is thicker and insulates the passenger from the heater. Link to comment Share on other sites More sharing options...
NC Tom Posted February 20, 2023 Author Share Posted February 20, 2023 Okay, is this the hose/line I am supposed to be looking for? I do get heat in the cab through the defroster. Honestly, I don't know if I get heat from the floor. Don't think I have ever checked. Not in a while anyway. Link to comment Share on other sites More sharing options...
pizzaman09 Posted February 21, 2023 Share Posted February 21, 2023 If you have non terminated vacuum lines like that, you probably would only have heat on defrost anyway due to the vacuum leaks. That sure looks like the correct line to me, should have a rubber 90 degree fitting on the end of the line. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 21, 2023 Share Posted February 21, 2023 Ditch the valve. Plug the tube. Link to comment Share on other sites More sharing options...
NC Tom Posted February 21, 2023 Author Share Posted February 21, 2023 7 minutes ago, cruiser54 said: Ditch the valve. Plug the tube. I'll do it! Link to comment Share on other sites More sharing options...
Armyvet25 Posted February 22, 2023 Share Posted February 22, 2023 Yeah, I prefer to have mine operational just to keep the heat down in the summer, even ordered a replacement already, will probably install a temporary T fitting in it's place first to flush the system good then remove and re-install the new valve, Will the world end and beer sour if you don't have it....no, but it does serve a purpose. Link to comment Share on other sites More sharing options...
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