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Unread 12-05-2013, 01:28 AM   #1
xj89can
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1989 XJ Cherokee 
 
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freezing canadian

its cold out!!! why cant i find my no heat issue?....new water pump,new thermo 195,blows hard! switches between heat/ def/vent,flushed,running temp is a little lower than usual,{almost half on gauge]. it did work a week ago.is there a vac line i may have put in wrong spot that would draw straight cold.please help its really fricking cold!!!
thank you

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Unread 12-05-2013, 01:29 AM   #2
xj89can
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oops...its 4.o 1989...
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Unread 12-05-2013, 02:33 AM   #3
JMH21814
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While the jeep is running and up to temp with the heat on, feel the 2 hoses on the right side of the valve cover that lead to the firewall. Upper (bigger) is your heater core inlet, lower (slightly smaller) is the h/c outlet. They both should feel pretty hot. If the outlet is warm or even cool (by comparison) then you likely have a clogged heater core.
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Unread 12-05-2013, 04:36 AM   #4
xj89can
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yup,that sounds about my luck, best flush and or method suggestions before replacement?........thank you
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Unread 12-05-2013, 05:01 AM   #5
cruiser54
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Also, your heater control valve may be stuck or restricted. Best to remove it and install a piece of tubing in it's place. Plug the vacuum line to it.
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If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
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Unread 12-06-2013, 05:49 PM   #6
xj89can
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so ive done another flush and blew threw the system both ways with air.....it blows threw no problem.....and theres a little bit of heat and when i throttle theres more heat,like i said the blower works good,,,,,,so what vac lines will i need to look at...any sort of diagram or routing descrition would be great...thks
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Unread 12-06-2013, 09:07 PM   #7
cruiser54
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Grab ahold of the hoses where they go into the firewall from the engine bay. Are they as hot as the radiator hoses? Are they both pretty much the same temp?
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If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
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Unread 12-07-2013, 11:09 AM   #8
melancholy35
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If you get heat when stepping on the accelerator but not at idle, you could have air trapped in the system.
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Unread 12-07-2013, 11:24 AM   #9
xj89can
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ok ill try burpinging more and check that the h/c hoses match the rad hoses.
nothing about vac lines ?
thks
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Unread 12-07-2013, 02:17 PM   #10
Paradise XJ
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There are two vacuum lines coming out of the firewall just next to the heater hoses...one is black and goes to the vacuum reservoir behind the pass front bumper. The other line coming out of the firewall is pink(ish) and should attach to the heater control valve.

I'm not exactly sure which way it goes (either vacuum applied opens the valve...or lack of vacuum opens the valve) but those two lines are responsible for ALL the vacuum for the HVAC system. Starting at the SOURCE vacuum that comes from the intake manifold, to the reservoir (behind the bumper) through the black line, out the pink line (as I understand it).



The line coming off the manifold (lower right) crosses over/behind the engine to provide vacuum to the reservoir.



The pink line goes to the heater control valve. Yours looks different (Mine is a 90 Renix but I relocated the vacuum reservoir and I'm using a 91+ heater valve because I converted to an open system) but it's the same pink hose. If you have a broken or missing/disconnected line anywhere along this line your either your blend doors won't operate properly or your valve won't open...or both.

These lines have nothing to do with the emissions system or how the truck runs, UNLESS the leak is at the manifold or from the manifold to the reservoir. then it will present as a high idle condition (in my experience)

I have since deleted the heater valve and run the hoses strait from the thermostat to the water pump, just like a 97+. It works fine and does not interfere with the A/C. It also allowed me to clean this whole area up...no more hoses running everywhere...I also deleted all the front axle vacuum lines and locked over the axle so further eliminating more vac lines.
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I slide it in and then when I pull, it works fine.
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Unread 12-07-2013, 03:51 PM   #11
xj89can
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thks Paradise xj,,i hope that will clear things up,i also have my vacume ball moved along with the stock air box thats why im wondering which effect the heat, ....has anyone else deleted the air box and how did they go about re routing theses lines?...maybe i crossed mine in the process
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Unread 12-07-2013, 04:50 PM   #12
cruiser54
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Keep the ball. Ditch the valve and plug the hose.
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If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
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Unread 12-07-2013, 05:11 PM   #13
Paradise XJ
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The air box vac lines don't have anything to do with the HVAC system. That's another story.

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Keep the ball. Ditch the valve and plug the hose.
That would be the simple way, if you didn't have to consider the radiator, or overflow or heater hoses without a valve. For now, just fix the vac line.
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I slide it in and then when I pull, it works fine.
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Unread 12-07-2013, 05:20 PM   #14
SKELITOR117
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Try checking under the passenger side dash for a little black motor connected to the firewall. Turn you car off but keep the heat on with NO fan. Switch back and forth between hot and cold and see if you hear the motor working. If not, than you just aren't switching over to heat, and you have to replace a few things by taking the dash off, or so I understand it.
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Unread 12-07-2013, 06:00 PM   #15
Paradise XJ
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It's an 89
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Quote:
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I slide it in and then when I pull, it works fine.
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