drase Posted March 18, 2014 Share Posted March 18, 2014 My A/C and Vent mode will only work in Defrost mode. No air will blow out of vents on dash that blow towards the driver & passenger. Anyone got an idea what the problem is? Link to comment Share on other sites More sharing options...
54bobby Posted March 18, 2014 Share Posted March 18, 2014 I think if I remember correctly, there is a vacume line that connects to a bladder under the front bumper. check the lines. some of the more knowledgeable guys will chime in shortly I'm sure. Link to comment Share on other sites More sharing options...
92tanMJ Posted March 18, 2014 Share Posted March 18, 2014 Yep there is a vacume ball in the fornt bumper. I would check that first, is they become damaged pretty easiley. Does it blow out of the vents in heat mode? If not I would check the vacume lines, the mechanical flapper, and check to make sure the hoses are still hooked up the the dash vents. Link to comment Share on other sites More sharing options...
drase Posted March 18, 2014 Author Share Posted March 18, 2014 Not sure about in heat mode, its still hot in FL so haven't tried it, but will now. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 18, 2014 Share Posted March 18, 2014 On the passenger side firewall is a black tube traveling down behind the battery and into the back side of the passenger side front bumper. That hose gets cracked, eaten by battery acid etc. I generally move the "ball" from the bumper up into the engine bay not far from where the black line enters the firewall. On Renix Jeeps, mounting it to the bottom side of the metal plate which holds the coolant bottle works very well. Link to comment Share on other sites More sharing options...
92tanMJ Posted March 18, 2014 Share Posted March 18, 2014 Not sure about in heat mode, its still hot in FL so haven't tried it, but will now. If it doesnt blow out in the vents in heat mode as well then it's most likely a vacume issue or the flappers stuck on defrost Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 18, 2014 Share Posted March 18, 2014 On the passenger side firewall is a black tube traveling down behind the battery and into the back side of the passenger side front bumper. That hose gets cracked, eaten by battery acid etc. I generally move the "ball" from the bumper up into the engine bay not far from where the black line enters the firewall. On Renix Jeeps, mounting it to the bottom side of the metal plate which holds the coolant bottle works very well. Here's one way to do it. Just make sure you keep the vacuum check valves in-lined properly. : http://comancheclub.com/topic/16154-vacuum-reservoir-relocation/?hl=caveman Link to comment Share on other sites More sharing options...
cruiser54 Posted March 18, 2014 Share Posted March 18, 2014 Nice underhood light switch. Kinda "retro"...... Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 18, 2014 Share Posted March 18, 2014 Nice underhood light switch. Kinda "retro"...... :yes: Yeah, the original mercury switch drove me crazy. Wish now I had done it in black though...... Link to comment Share on other sites More sharing options...
cruiser54 Posted March 18, 2014 Share Posted March 18, 2014 I know the feeling. I leave it unplugged for the most part. Link to comment Share on other sites More sharing options...
Zebvance Posted March 18, 2014 Share Posted March 18, 2014 I have this problem too. The PO removed the "Ball" for some reason. Not trying to hi jack but does anybody know where I can get another? Ps. Mine is a factory non ac model Link to comment Share on other sites More sharing options...
cruiser54 Posted March 18, 2014 Share Posted March 18, 2014 I have this problem too. The PO removed the "Ball" for some reason. Not trying to hi jack but does anybody know where I can get another? Ps. Mine is a factory non ac model No cruise? Look under the hood of most any Ford or Chevy and you'll see them. Mine looks like a big soup can and came off a Ford. Link to comment Share on other sites More sharing options...
Zebvance Posted March 18, 2014 Share Posted March 18, 2014 I have this problem too. The PO removed the "Ball" for some reason. Not trying to hi jack but does anybody know where I can get another? Ps. Mine is a factory non ac model No cruise? Look under the hood of most any Ford or Chevy and you'll see them. Mine looks like a big soup can and came off a Ford. No cruise from the factory either. do you know what the actual name is. I will order it off ebay now if I could find it. Link to comment Share on other sites More sharing options...
88whitemanche Posted March 18, 2014 Share Posted March 18, 2014 Vacuum canister Link to comment Share on other sites More sharing options...
Zebvance Posted March 18, 2014 Share Posted March 18, 2014 does any body have a vacuum schematic that shows it. It would prolly help me and the OP. Link to comment Share on other sites More sharing options...
Guest Posted March 18, 2014 Share Posted March 18, 2014 Another thing of note I discovered upon taking apart the dash in my 87. There is a small Y shaped inlet tube where 3 lines meet; it's about 5 or 6 inches back from where the HVAC controls are located (headed towards the passenger side). Not sure if it's the same for later models, but sometimes the Y connector can disengage itself from one of the lines, hence, defrost only mode. I chased vacuum lines all over my truck like the others said, only to finally discover they weren't the problem. Took long enough, and now I have working air again. If you can't find a leak in your system, this may be the problem... :smart: Link to comment Share on other sites More sharing options...
92tanMJ Posted March 19, 2014 Share Posted March 19, 2014 I have this problem too. The PO removed the "Ball" for some reason. Not trying to hi jack but does anybody know where I can get another? Ps. Mine is a factory non ac model Junk yard would probably have a couple cheap if theyres one close to you. Or someone parting out an MJ or XJ. Pretty sure the one in my 92 and 98 are the same... Red Rocker79, on 18 Mar 2014 - 5:32 PM, said: Another thing of note I discovered upon taking apart the dash in my 87. There is a small Y shaped inlet tube where 3 lines meet; it's about 5 or 6 inches back from where the HVAC controls are located (headed towards the passenger side). Not sure if it's the same for later models, but sometimes the Y connector can disengage itself from one of the lines, hence, defrost only mode. I chased vacuum lines all over my truck like the others said, only to finally discover they weren't the problem. Took long enough, and now I have working air again. If you can't find a leak in your system, this may be the problem... [ :smart:] On the later models it's behind the glove box but same issue Link to comment Share on other sites More sharing options...
carnuck Posted March 19, 2014 Share Posted March 19, 2014 Also see if the vacuum hose is off the vacuum motor right above the gas pedal. A new vacuum ball is about $17 at Napa. Here's mine mounted under the hood (my bumper is extended forward for a hideaway winch) Link to comment Share on other sites More sharing options...
1989 Eliminator Posted March 21, 2014 Share Posted March 21, 2014 Yup if you move the vaccum canister under the coolant bottle, you can use some of the old lines (if they are good) to hook everything back up normal. This will eliminate a TON of vaccum line which in return gives less of a change of a leak. I can send pictures if wanted. Link to comment Share on other sites More sharing options...
drase Posted June 25, 2014 Author Share Posted June 25, 2014 A vacuum line was broke. Replaced it and blows cool air through all vents! Link to comment Share on other sites More sharing options...
cruiser54 Posted June 25, 2014 Share Posted June 25, 2014 A vacuum line was broke. Replaced it and blows cool air through all vents! Gotta love it!! Congrats. Link to comment Share on other sites More sharing options...
floridaftwman Posted May 12, 2019 Share Posted May 12, 2019 I had this problem, and thanks to the forum I was able to isolate it. My canister has two tubes. I inspected and replaced one labeled "vac" that routes to the three way connector. The second hose was severed near its connection going through the firewall. I taped it up and got it to work, restoring function of the vents. However, I don't reckon this is gonna last. What are thoughts on using heat shrink tubing for a more secure repair? Best bet on getting a replacement?? can't find what this part is called for the life of me. Link to comment Share on other sites More sharing options...
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