88eliminator Posted December 4, 2014 Share Posted December 4, 2014 Hello, my first post . I have a 1988 Comanche Eliminator and was wondering why when ever I turn on my air conditioner or heater it only comes out the defroster? The vents that are facing at you when in the truck seem to not be working. I was wondering if anyone else has had this problem or is it normal which seems kinda odd. Any input will help a lot, Thanks. Link to comment Share on other sites More sharing options...
Dillithium Posted December 4, 2014 Share Posted December 4, 2014 That means you have a vacuum leak. The different vents are operated by vacuum from the engine. Check the vacuum canister to make sure it's not leaking(passenger side, inside the front bumper) and follow the lines going inside your firewall. Check for leaks and replace as necessary. Sometimes, the Y connector behind your heater control seperates so you may want to check that; although I've been unable to find that connector myself. Link to comment Share on other sites More sharing options...
az comanches Posted December 4, 2014 Share Posted December 4, 2014 I've got a similar problem, there are two lines at my firewall. A grey one and a white one, the white one runs over to the heater valve, does the grey one go to the heater control panel. Is that the one supplying the vacuum for the controls? Link to comment Share on other sites More sharing options...
sloride Posted December 4, 2014 Share Posted December 4, 2014 From firewall side, disconnect vacuum lines going into cab and try pulling vacuum with vacuum hand pump mity vac gauge. If there's no vacuum then your hose is disconnected somewhere. Link to comment Share on other sites More sharing options...
HOrnbrod Posted December 6, 2014 Share Posted December 6, 2014 Link to comment Share on other sites More sharing options...
CGCWO Posted December 6, 2014 Share Posted December 6, 2014 Had this same problem, turned out when the PO took out the radio or when I installed the new one the lines on the top/back of the actual AC/Heater/Vent controls were disconnected, prob form something pushing against them. Link to comment Share on other sites More sharing options...
Guest Posted December 8, 2014 Share Posted December 8, 2014 Had this same problem, turned out when the PO took out the radio or when I installed the new one the lines on the top/back of the actual AC/Heater/Vent controls were disconnected, prob form something pushing against them. This. I chased vacuum lines 'til I was blue in the face all around the engine bay. When I took the dash out for the heater core replacement, I found that AMC had the bright idea to stick two lines together inside of a rubber connector. If you even breathe wrong on the thing, they will slide apart. If you can't find a leaking vacuum line in the engine bay (there are only 2-3 you need to check for) then this will be your culprit. Link to comment Share on other sites More sharing options...
88eliminator Posted December 8, 2014 Author Share Posted December 8, 2014 Had this same problem, turned out when the PO took out the radio or when I installed the new one the lines on the top/back of the actual AC/Heater/Vent controls were disconnected, prob form something pushing against them. Can you check the lines with out taking the whole dash off? If so how? and is the AC/Heater/vent controls locaded under the glove box? Link to comment Share on other sites More sharing options...
sloride Posted December 9, 2014 Share Posted December 9, 2014 Has your dash ever been dropped that you know of? Unless your dash has been tampered with in the past, I would eliminate all other possible leak options before you think about your dash. Answer to your question. I will tell you no, you can't check the lines behind your dash without dropping the dash. Even without a radio I could barely see back behind the dash let alone get my hand back there. Those lines that operate your selector switch by vacuum are bound together in a plastic wire loom. At least mine has the loom. And Red Rocker79 is correct, there is a splice within that loom (one into two line) that is touchy. I dropped my dash for heater/ac work earlier this year and during the process unknowingly separated that splice. Only after much cigar smoke and pulling vacuum did I drop the dash again to inspect those lines. Link to comment Share on other sites More sharing options...
sloride Posted December 9, 2014 Share Posted December 9, 2014 http://www.cherokeeforum.com/f51/dash-removal-35444/ Here's an idea what you have to go through to work on your dash. Granted, this guy took his dash out completely, you won't have to do all what he did. There's two fasteners, one at each door jamb, that the dash will 'hinge' down to grant you access. That is after you take off all the necessary fasteners. Link to comment Share on other sites More sharing options...
88eliminator Posted December 9, 2014 Author Share Posted December 9, 2014 Has your dash ever been dropped that you know of? Unless your dash has been tampered with in the past, I would eliminate all other possible leak options before you think about your dash. Answer to your question. I will tell you no, you can't check the lines behind your dash without dropping the dash. Even without a radio I could barely see back behind the dash let alone get my hand back there. Those lines that operate your selector switch by vacuum are bound together in a plastic wire loom. At least mine has the loom. And Red Rocker79 is correct, there is a splice within that loom (one into two line) that is touchy. I dropped my dash for heater/ac work earlier this year and during the process unknowingly separated that splice. Only after much cigar smoke and pulling vacuum did I drop the dash again to inspect those lines. The dash has not been touched ever sense it was new. I am going to look every where else and leave the dash the last thing i need to check if needed. Thanks for the tips about the dash, i'm sure i'm going to need them in the future. On the other hand I did find out that the Vacuum line connected to the Vacuum Reservoir wasn't connected. Whats the easy way to get to the vacuum reservoir? I do know that its behind the bumper on the passenger side. Thanks for all the input. Link to comment Share on other sites More sharing options...
sloride Posted December 9, 2014 Share Posted December 9, 2014 Someone else will have to chime in since I don't have any experience getting to the vacuum reservoir. I just know it looks like a real PITA to get to. Try doing a forum search to see if any tips/tricks pop up. Link to comment Share on other sites More sharing options...
HOrnbrod Posted December 9, 2014 Share Posted December 9, 2014 Recommend just leaving it there and simply mount and plumb a new reservoir in the engine bay where it belongs. http://comancheclub.com/topic/16154-vacuum-reservoir-relocation/?hl=reservoir Link to comment Share on other sites More sharing options...
88eliminator Posted December 10, 2014 Author Share Posted December 10, 2014 I found many forums about the vacuum reservoir that where helpful. My plan is to try and relocate the reservoir in the engine bay so I don't have to worry about getting behind the front bumper. I have a couple more questions to ask. Could the vacuum reservoir cause a rough low idle if one of the vacuum lines was found unplugged? My idle moves up and down and won't hold a constant good idle. Idles around 650 to 700 RPMs. But it drives good with plenty of power and no power loss. and some say that its not good to drive the truck with the reservoir leaking, what could it hurt on your truck? Note: I don't have 4x4 but I do have cruise control that works but has a delay. Link to comment Share on other sites More sharing options...
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