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Thread: Crappy heat

  1. #1
    Angry Midget apstang50's Avatar
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    Crappy heat

    The heat in my niner has never really been all that great, compared to the 93 5.2 I had. The heat in that one would melt your skin off after 10 min! I replaced my water pump last year, I've got a new rad cap, t stat is only a few years old. T stat is a 195*. Coolant level is full, not low. I've tried flushing the heater core both ways are few times never really getting any crap out of it. What could be other causes for poor heat output? I'd really like to take care of it before it really starts to get cold.
    98 Platimum GC 5.9 Limited Flowmaster, relocated intake temp sensor, clear corners, 35% front tint, 5% sunroof tint, white face gauges, Accel coil, Summit Racing 8MM wires, 100w fog lights w/new housings, Mopar tow hooks, Mopar Performance PCM, Summit Racing drilled/slotted rotors w/ EBC pads, K&N FIPK

    SOLD 90 Mustang LX notchback: cobra intake, 70mm TB and spacer, fender mounted CAI, 1 3/4" long tube headers, 2 1/2" offroad h-pipe, 2 chamber flowmasters, 3.73s, subframe connecters, cobra r glass hood, glass decklid, 5-spd, cobra rims, underdrive pullys, e-fan, Steeda short through shifter


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    X2, mines the same way and replaced all the same as you

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    Angry Midget apstang50's Avatar
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    Quote Originally Posted by CLEAN AND SLAMMED View Post
    X2, mines the same way and replaced all the same as you
    I hope your butt warmers work as good as mine

    - - - Updated - - -
    98 Platimum GC 5.9 Limited Flowmaster, relocated intake temp sensor, clear corners, 35% front tint, 5% sunroof tint, white face gauges, Accel coil, Summit Racing 8MM wires, 100w fog lights w/new housings, Mopar tow hooks, Mopar Performance PCM, Summit Racing drilled/slotted rotors w/ EBC pads, K&N FIPK

    SOLD 90 Mustang LX notchback: cobra intake, 70mm TB and spacer, fender mounted CAI, 1 3/4" long tube headers, 2 1/2" offroad h-pipe, 2 chamber flowmasters, 3.73s, subframe connecters, cobra r glass hood, glass decklid, 5-spd, cobra rims, underdrive pullys, e-fan, Steeda short through shifter


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    Our '95 4.0 was VERY cold-blooded, as is our friend's '95 4.0. Another friend's former '95 5.2L would melt glaciers. It hasn't turned super-cold here yet, and both my wife and I are hoping the 5.9L will put out winter heat like a blast furnace. These posts are not making me optimistic.

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    Quote Originally Posted by apstang50 View Post
    I hope your butt warmers work as good as mine

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    Actually for some reason that's the only option mine didn't come with well that and sunroof

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    Modfag Saleen4971's Avatar
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    Could try one of those bottles of cooling system flush. Might be some sticky gunk in the core
    Ross
    1998 Grand Cherokee 5.9 Limited
    MPP Headers - Thunderbolt Metallic Cat - 3" Mag catback - EBC Brakes w/ drilled Rotors - 4bbl M1 - Vortech 12psi - Built trans & 2900 stall - Ford 8.8 - Addco & Hellwig Sways - Poly Bushings - H&R Springs - Grabber UHP Tires - Alpine/Infinity Stereo - FX-R BiXenon Retrofit

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    Member Snowfan's Avatar
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    I dropped my interior fan motor on my 96ZJ and used a telescoping mirror to look at the heater core. It was completely covered up halfway down with gunk that was sucked in there. Cleaned it out and heater worked again. Pop off the trim panel, 3 screws and elect plug. EZ fix. You can use coil cleaner or a flexible shop vac mini nozzle.

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    Forum CONDUCTOR Man Z88Z's Avatar
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    That's a good tip ^

    We don't have any cabin filter on our ZJs, just a plastic screen with maybe 3/8 x 3/8 square holes.

    That allows lots of crap to get sucked in

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    Angry Midget apstang50's Avatar
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    Quote Originally Posted by Saleen4971 View Post
    Could try one of those bottles of cooling system flush. Might be some sticky gunk in the core
    I ran some through the whole cooling system a few years ago, then flushed the heater core. I didn't really see anything come out of it, it seamed to have good flow to. I wonder if it could be clogged with shit that got sucked in from the vent.
    98 Platimum GC 5.9 Limited Flowmaster, relocated intake temp sensor, clear corners, 35% front tint, 5% sunroof tint, white face gauges, Accel coil, Summit Racing 8MM wires, 100w fog lights w/new housings, Mopar tow hooks, Mopar Performance PCM, Summit Racing drilled/slotted rotors w/ EBC pads, K&N FIPK

    SOLD 90 Mustang LX notchback: cobra intake, 70mm TB and spacer, fender mounted CAI, 1 3/4" long tube headers, 2 1/2" offroad h-pipe, 2 chamber flowmasters, 3.73s, subframe connecters, cobra r glass hood, glass decklid, 5-spd, cobra rims, underdrive pullys, e-fan, Steeda short through shifter


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    Modfag Saleen4971's Avatar
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    Could be. I've been thinking I may have leaves and crap stuck in mine as well.
    Ross
    1998 Grand Cherokee 5.9 Limited
    MPP Headers - Thunderbolt Metallic Cat - 3" Mag catback - EBC Brakes w/ drilled Rotors - 4bbl M1 - Vortech 12psi - Built trans & 2900 stall - Ford 8.8 - Addco & Hellwig Sways - Poly Bushings - H&R Springs - Grabber UHP Tires - Alpine/Infinity Stereo - FX-R BiXenon Retrofit

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    King Dumbass McCloudsZJ's Avatar
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    I'll be doing the heater core flush on the 96 sometime soon. I has zero heat.

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    The no heat issues on the ZJ's is caused by an issue with the blend doors. On my 96 that I have owned for 14 years it developed after I had the heater core replaced. My lead tech. at the shop I used to run went through everything in the entire heating system [as did the other tech that put the core in]. It is an issue with the blend doors letting outside air in. I need to address it but just don't feel like pulling out the dash again. Yes the core gets plugged externally with leaves [you do have the screens on it I hope]. But that is generally not the issue unless it is completely plugged and to clean it properly you have to R&R the dash. I have yet to determine what exactly goes wrong but it is very common so someone out there must know. Hope this helps Roger

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    I just noticed today that outa the four front face vents on the dash only one is letting heat thru and its barely any at all, my windshield ones work fine tho , guessing blend door?

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    im super special x10radsponge's Avatar
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    yea, but what is causing it. I know several problems from broken parts to leaking vacuum lines. Mine does the same.

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    Forum CONDUCTOR Man Z88Z's Avatar
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    Quote Originally Posted by Roger Berkan View Post
    The no heat issues on the ZJ's is caused by an issue with the blend doors. .....
    Quote Originally Posted by x10radsponge View Post
    yea, but what is causing it. I know several problems from broken parts to leaking vacuum lines. Mine does the same.

    Interesting. I know the blend doors were a big problem on the WJs but I don't think I've heard of that on ZJs before. But, if that's what the tech said I guess I'd believe it.

    Roger - did he have any more info on it - did he know if they weren't operating at all, or did he just know they weren't sealing or opening correctly?


    The ATC head unit is fairly sophisticated and has all kinds of failure codes, but I think that may be for simpler things like whether a door motor is actually working when it's supposed to. I doubt it has enough sensors to compare temps through out the system to see if things are actually opening and sealing correctly by comparison though

    I thought it would give an 'ERR' code if something was wrong, but that might only be if you were interrogating it or something. I know it doesn't give that ERR message when we have all the lower motor problems though.
    I'd have to look at the FSM but I seem to recall that we have access to some diagnostics by interrogating it through manual use of combinations of buttons or something.



    Kevin - is your AC an ATC type or the manual type?

    The ATC systems don't use vacc lines, but the manual type does. At least, I know that was the case on early ZJ manual vs ATC systems. It could have changed when they went OBD2 but I don't think it did.



    Speaking of the screens, I've been thinking I'd throw some window type screening on the back of mine. That should keep a bit more debris out than our current setup while still allowing decent airflow.

    I also know a few of us have had problems with mice nesting in the AC system!

    I found that on my lightweight. Not sure exactly how they got in there - my screen was intact and those holes are a wee bit too small for mice, LOL I think that problem is only going to be found on ZJs that sat for a few weeks or months though.

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    Angry Midget apstang50's Avatar
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    Quote Originally Posted by Roger Berkan View Post
    The no heat issues on the ZJ's is caused by an issue with the blend doors. On my 96 that I have owned for 14 years it developed after I had the heater core replaced. My lead tech. at the shop I used to run went through everything in the entire heating system [as did the other tech that put the core in]. It is an issue with the blend doors letting outside air in. I need to address it but just don't feel like pulling out the dash again. Yes the core gets plugged externally with leaves [you do have the screens on it I hope]. But that is generally not the issue unless it is completely plugged and to clean it properly you have to R&R the dash. I have yet to determine what exactly goes wrong but it is very common so someone out there must know. Hope this helps Roger
    As John (z88z) said, I didn't think the zj's had the blend door problems, it was the wj's. Anything is possible though. It's not that I don't have heat, I do it's just not hot like it should be.
    98 Platimum GC 5.9 Limited Flowmaster, relocated intake temp sensor, clear corners, 35% front tint, 5% sunroof tint, white face gauges, Accel coil, Summit Racing 8MM wires, 100w fog lights w/new housings, Mopar tow hooks, Mopar Performance PCM, Summit Racing drilled/slotted rotors w/ EBC pads, K&N FIPK

    SOLD 90 Mustang LX notchback: cobra intake, 70mm TB and spacer, fender mounted CAI, 1 3/4" long tube headers, 2 1/2" offroad h-pipe, 2 chamber flowmasters, 3.73s, subframe connecters, cobra r glass hood, glass decklid, 5-spd, cobra rims, underdrive pullys, e-fan, Steeda short through shifter


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    check the blend door actuator , as ther is a plastic white gear that is prone to be cracked and limits the blend door travels , once fixed the door will fully engage you can test it by manually closing the door to see if the heat gets better .
    98 GRAND CHEROKEE 5.9 , "junkyard land" until the next one

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    Angry Midget apstang50's Avatar
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    Quote Originally Posted by dcgear360 View Post
    check the blend door actuator , as ther is a plastic white gear that is prone to be cracked and limits the blend door travels , once fixed the door will fully engage you can test it by manually closing the door to see if the heat gets better .
    This can be done with out removing anything from the jeep?
    98 Platimum GC 5.9 Limited Flowmaster, relocated intake temp sensor, clear corners, 35% front tint, 5% sunroof tint, white face gauges, Accel coil, Summit Racing 8MM wires, 100w fog lights w/new housings, Mopar tow hooks, Mopar Performance PCM, Summit Racing drilled/slotted rotors w/ EBC pads, K&N FIPK

    SOLD 90 Mustang LX notchback: cobra intake, 70mm TB and spacer, fender mounted CAI, 1 3/4" long tube headers, 2 1/2" offroad h-pipe, 2 chamber flowmasters, 3.73s, subframe connecters, cobra r glass hood, glass decklid, 5-spd, cobra rims, underdrive pullys, e-fan, Steeda short through shifter


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    I took Z88Z picture and circled where the blend door motor is located , pretty much accessible but it is tight.
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    98 GRAND CHEROKEE 5.9 , "junkyard land" until the next one

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    The blend doors are moving on mine [at least some of them] Blend door motor and gear is not the problem on mine. Ordered the fixer kit and it was a complete waste. My sleeve was fine but the motor had quit. When that happened I had NO heat at all. I replaced it and now it is back to the crappy heat. The issue with finding out what is wrong is you have to pull the dash and when you do that it is very hard to check all the doors and actuators. Mine also has no trouble codes. It just plane sucks. Before the 97 got totaled I checked the temp difference between the two and I had around 115 on the 96 and around 166 or so on the 97. The 54.9 is about the same as the 96 and we could find nothing wrong when the dash was out. So who the hell knows. Roger

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    from the FSM

    - - - Updated - - -

    heres a pic of a cracked gear from the below link , good read
    http://www.jeepforum.com/forum/f13/r...uator-1418176/
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    98 GRAND CHEROKEE 5.9 , "junkyard land" until the next one

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    Would heat only come out of certain places with a cracked gear or does the heat just suck when this happens? Or both ?

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    heat will suck... as this is the tempature door blender , where as it is controlled by the tempature sensor and tempature setting , as it adjust the door to adjust tempature , most likely this door is stuck half open and will get yourself crappy heat , once you remove this door actuator , you can manually turn the shaft , i think it is clockwise to close or the orherway around cant remember eirher way once closed you should feel a difference in tempature. if for somereason the door motor is working properly . thr FSM says check for obstruction on the intake , screen area , or plugged heater core. blend door was my issue and now i have hot heat .goodluck
    98 GRAND CHEROKEE 5.9 , "junkyard land" until the next one

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    Do u gotta take the dash out to get to the screen?

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    the screen, i believe they are referring to is under the cowl area remove plastic 4 plastic screw things , remove wipers . then remove plastic cowl piece and there you will see the screen . its also where i hid my msd 6al , fits perfect , anyways ,straight from FSM
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    98 GRAND CHEROKEE 5.9 , "junkyard land" until the next one

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