yj heat problem - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Wrangler Forums > YJ Wrangler Technical Forum > yj heat problem

FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitFlowmaster's Force II Axle-back exhaust system for the 201FS: Wranger BRIGHT License Plate LED! Just $3! Great value

Reply
Unread 12-10-2010, 07:30 AM   #1
1993redjeepyj
Registered User
 
Join Date: Oct 2008
Location: North Jersey
Posts: 341
yj heat problem

hello all !!!!


ok, so i have spent the last few hours creeping through all the "heat problems" and "no heat" threads that my eyes could possibly take and i still dont have an answer.

heres my issue:

my heat in my jeep has never givin me a single issue. its always been very good for what it is. its all stock stuff.

but for the past few, really cold, days it has been acting up. i have heat but its weak as if the heat door is not closing all the way.

now i just came out from under the dash with the jeep running playing with the controls.

my question is on the passanger side there is a slide on the front side of the heater box, that moves all the way shut with the "cold/hot" slide. now closer the the passanger side door is another box with a filter looking thing on it right next to where like the antenna wire runs through the body.

whatever that is has another cable attached to it on the outside with a slide. the filter thing moves in and out when i manually turn it.

now when i turn it to the open possition the heat coming out the bottom vent becomes ALOT hotter like what it normally was.

what is that door? what is its function? what is the cable/slide supposed to be connected to?

anyone know?


thanks steve.

any help is appreciated, its getting very very cold out here in jersey.

__________________
1993 Red jeep wrangler YJ, 2.5L-----SOLD
1997 Blue ford f150, 5.4L----SOLD
1996 Jeep Grand Cherokee 5.2L V8------SOLD
1991 GMC Seirra 5.7L----Project truck
2010 Hyundia Accent BLUE------Current DD
1993redjeepyj is offline   Reply With Quote
Unread 12-10-2010, 07:35 AM   #2
Longhorn
Registered User
1995 YJ Wrangler 
 
Join Date: Aug 2009
Location: Central PA
Posts: 211
I'll get dressed and go look at miine. can at least tell you what it's connected to. My guess is it's a recirculator to draw air from the cab instead of outside
Longhorn is offline   Reply With Quote
Unread 12-10-2010, 07:42 AM   #3
1993redjeepyj
Registered User
 
Join Date: Oct 2008
Location: North Jersey
Posts: 341
here is a pic i just took.
5555555555555555555.jpg  
__________________
1993 Red jeep wrangler YJ, 2.5L-----SOLD
1997 Blue ford f150, 5.4L----SOLD
1996 Jeep Grand Cherokee 5.2L V8------SOLD
1991 GMC Seirra 5.7L----Project truck
2010 Hyundia Accent BLUE------Current DD
1993redjeepyj is offline   Reply With Quote
Unread 12-10-2010, 07:45 AM   #4
Longhorn
Registered User
1995 YJ Wrangler 
 
Join Date: Aug 2009
Location: Central PA
Posts: 211
You know where the lever is to open and close it right? On mine there's a cable coming straight down from up by the dash that opens and closes it when you slide the heater control from "heat" to "vent" I assume you want it to be open for heat, to draw the warmer air from the inside of the cab. I would try to fnd a way to keep it held open all winter.
Longhorn is offline   Reply With Quote
Unread 12-10-2010, 07:49 AM   #5
1993redjeepyj
Registered User
 
Join Date: Oct 2008
Location: North Jersey
Posts: 341
it stays open. like just from pushing it open manualy. mine has a cable connected to it that runs striaght up under the dash but i loose the cable halfway to the heat controls.... so when you slide yours to heat the little filter looking thing is open or closed?
__________________
1993 Red jeep wrangler YJ, 2.5L-----SOLD
1997 Blue ford f150, 5.4L----SOLD
1996 Jeep Grand Cherokee 5.2L V8------SOLD
1991 GMC Seirra 5.7L----Project truck
2010 Hyundia Accent BLUE------Current DD
1993redjeepyj is offline   Reply With Quote
Unread 12-10-2010, 07:56 AM   #6
Longhorn
Registered User
1995 YJ Wrangler 
 
Join Date: Aug 2009
Location: Central PA
Posts: 211
I can't see behind the filter to know what's open or closed, but when you slide it to "vent" the cable pushes the lever down, to what I'm assuming would be closed to draw air from outside. When you slide it back to "heat", it pulls the lever up.
Longhorn is offline   Reply With Quote
Unread 12-10-2010, 08:05 AM   #7
1993redjeepyj
Registered User
 
Join Date: Oct 2008
Location: North Jersey
Posts: 341
beautiful!

thank you longhorn!

when i manualy push the lever up it opens the door and that is when i get alot hotter air coming out the bottom vent.

so that cable is supposed to be connected to the "vent/heat" slide.

thank you so much. im going to pull the heat control out now and see it i can see where that cable is not connected and if i cant ill just keep it pushed open this winter and worry about it in the spring.

once again THANK YOU, you saved my butt alot of cold times hahaha
__________________
1993 Red jeep wrangler YJ, 2.5L-----SOLD
1997 Blue ford f150, 5.4L----SOLD
1996 Jeep Grand Cherokee 5.2L V8------SOLD
1991 GMC Seirra 5.7L----Project truck
2010 Hyundia Accent BLUE------Current DD
1993redjeepyj is offline   Reply With Quote
Unread 12-10-2010, 08:10 AM   #8
brewer
Registered User
2000 WJ 
 
Join Date: Jan 2006
Location: Vancouver
Posts: 270
its the recirc vent like everyone was talking about. the cable may have snapped... try moving your controls to the vent and see if it operates. If it does, then this is NOT your problem - unless there is something jamming it from actually fully closing / opening such as dirt or debris.

Another couple easy things to check.... with regards to heat in cold temperatures...

Coolant - is it full? what is the temp value on the coolant, meaning what is its freezing point? Most manufacturers recommend a 50/50 mixture, and some say 60/40 mixture of antifreeze with water. If you have more water than antifreeze your freeze point comes closer to zero but it should be looking for about -40 ish degrees on a proper mixture. If you have too much antifreeze, your freeze point goes off the scale and you also end up with heating problems. (There is a special tool gauge to check this freezing point, and almost any mechanical shop will test it for free - autozone seems to be a place in the USA where people recommend for some unknown reason to my Canadian knowledge! LOL! Maybe one day I'll visit one! LOL!)

You have not mentioned anything about engine heat so I assume this is normal, but please - do correct us if the gauge for engine temp has also been acting differently.

Couple other things to try.... stick some cardboard in front of your grill -> it will slow the cold air from hitting directly on your radiator, which will in turn help raise the temp of the engine, which can then raise the temp inside the cabin.

You can also easily disconnect the two heater core hoses from the back of the engine bay and then push water from one inlet and watch it come out the other outlet. Should have same amount of flow on both sides. Some systems will become plugged up if you park under too many trees during the fall. Give it a look and a try, BUT do not go full crazy on water flow. You need to simulate normal pressures, NOT excessive pressures which will just cause you to kill that heater core. Think of the amount of pressure you have when you turn your kitchen sink to about half way... not too hard, but not a tinkle either. This has worked on a few YJs I've had in my shop over the past couple months.

if you STILL have heat problems... buzz us back. Someone is bound to have some more ideas to get you warmed up.
__________________
Beauty is but a lightswitch away :D
brewer is offline   Reply With Quote
Unread 12-10-2010, 08:32 AM   #9
Matt The Hammer
Registered User
1995 YJ Wrangler 
 
Join Date: Oct 2007
Location: Westville, NJ
Posts: 980
There are three cables that control three things in the heater box.

- The 'vent' door
- The warm/cold door - blue tipped cable
- the defrost / floor door - red tipped cable

The air goes into the heater box through a vacuum powered door from the intake in front of the windshield on the hood/cowl. There is a fan that pushes the air through the heater box at various speeds. When you have the lever in the off position, the vacuum closes the air intake door and turns the fan off.

When the fan is on, it pushes air to the warm/cold door where it is either ran through the heater core or not.

Past there, the air hits the defrost/floor door. This just deflects the air to which exit it takes.

When the control lever is slid to 'vent', the vacuum door is opened, but the fan is off and the vent door opens and the air leaves the heater box there.

It's a simple system that is maddening to keep operating once it starts acting up. The cables are a pain to remove and the clips that hold the cables in place seem to break.

Then again, I never really work on my heater in the warm months when plastic bends a little more.
__________________
2013 JKU
1995 YJ
Matt The Hammer is offline   Reply With Quote
Unread 12-10-2010, 08:39 AM   #10
Matt The Hammer
Registered User
1995 YJ Wrangler 
 
Join Date: Oct 2007
Location: Westville, NJ
Posts: 980
Quote:
Originally Posted by 1993redjeepyj View Post
so that cable is supposed to be connected to the "vent/heat" slide.
There are two slides.

the vent heat slide on the top has two cables mounted to it, one for the defrost/floor door and the other is for the vent door that you are talking about.

The bottom lever is obviously the other one for the warm/cool air.

Getting the control unit out with the cable attached is a puzzle. The vent lines and the light bind it up when you pull it out.

Take your time and don't force it - they will snap off.
__________________
2013 JKU
1995 YJ
Matt The Hammer is offline   Reply With Quote
Unread 12-10-2010, 09:09 AM   #11
Brando0275
Registered User
2014 JK Wrangler 
 
Join Date: Apr 2010
Location: TN
Posts: 246
That vent door is connected to the door all the way over on the drivers side far left fresh air vent near the top of the upper air box. It closes those two together to stop the fresh air vent when you turn the heat on.

I will try to get you a pic
Brando0275 is offline   Reply With Quote
Unread 12-10-2010, 09:14 AM   #12
1993redjeepyj
Registered User
 
Join Date: Oct 2008
Location: North Jersey
Posts: 341
Quote:
Originally Posted by brewer View Post
its the recirc vent like everyone was talking about. the cable may have snapped... try moving your controls to the vent and see if it operates. If it does, then this is NOT your problem - unless there is something jamming it from actually fully closing / opening such as dirt or debris.

Another couple easy things to check.... with regards to heat in cold temperatures...

Coolant - is it full? what is the temp value on the coolant, meaning what is its freezing point? Most manufacturers recommend a 50/50 mixture, and some say 60/40 mixture of antifreeze with water. If you have more water than antifreeze your freeze point comes closer to zero but it should be looking for about -40 ish degrees on a proper mixture. If you have too much antifreeze, your freeze point goes off the scale and you also end up with heating problems. (There is a special tool gauge to check this freezing point, and almost any mechanical shop will test it for free - autozone seems to be a place in the USA where people recommend for some unknown reason to my Canadian knowledge! LOL! Maybe one day I'll visit one! LOL!)

You have not mentioned anything about engine heat so I assume this is normal, but please - do correct us if the gauge for engine temp has also been acting differently.

Couple other things to try.... stick some cardboard in front of your grill -> it will slow the cold air from hitting directly on your radiator, which will in turn help raise the temp of the engine, which can then raise the temp inside the cabin.

You can also easily disconnect the two heater core hoses from the back of the engine bay and then push water from one inlet and watch it come out the other outlet. Should have same amount of flow on both sides. Some systems will become plugged up if you park under too many trees during the fall. Give it a look and a try, BUT do not go full crazy on water flow. You need to simulate normal pressures, NOT excessive pressures which will just cause you to kill that heater core. Think of the amount of pressure you have when you turn your kitchen sink to about half way... not too hard, but not a tinkle either. This has worked on a few YJs I've had in my shop over the past couple months.

if you STILL have heat problems... buzz us back. Someone is bound to have some more ideas to get you warmed up.

*****coolent is new and coolent level is perfect. heatercore was flushed the begining of last summer because i was doing it on another car of mine at the time and i figured i might as well do it to the jeep since i never have.

engine temps are right where they always sit and they never really budge, exept once lol.
__________________
1993 Red jeep wrangler YJ, 2.5L-----SOLD
1997 Blue ford f150, 5.4L----SOLD
1996 Jeep Grand Cherokee 5.2L V8------SOLD
1991 GMC Seirra 5.7L----Project truck
2010 Hyundia Accent BLUE------Current DD
1993redjeepyj is offline   Reply With Quote
Unread 12-10-2010, 09:14 AM   #13
Brando0275
Registered User
2014 JK Wrangler 
 
Join Date: Apr 2010
Location: TN
Posts: 246
Here is the pic...got it somewhere in a forum a while back.
yj-cable-diagram.jpg  
Brando0275 is offline   Reply With Quote
Unread 12-10-2010, 09:17 AM   #14
Brando0275
Registered User
2014 JK Wrangler 
 
Join Date: Apr 2010
Location: TN
Posts: 246
the heat "on/off" vent was vacuum actuated on mine and i lost vacum or the actuator died...i flipped the lever by hand and removed the actuator and heat worked
Brando0275 is offline   Reply With Quote
Unread 12-10-2010, 09:17 AM   #15
Fenix85182
Registered User
1989 YJ Wrangler 
 
Join Date: Jan 2006
Location: Southeastern CT
Posts: 594
DON'T block the vent door open.

As outlined by Matt the Hammer, the vent door will open and shut the fan off. This lets air in directly from the outside. While in theory, it could act as a recirc, in function it's exactly opposite. This shuts off the fan and allows the air to move from an area of high concentration to low concentration (read: outside at whatever speed you're traveling to inside where cabin pressure is lower).

Our heating systems function on the coolant level in the cooling system. When appropriately full, it builds up pressure and circulates through the system, heating up the heater core. Since the heater core is in the back of the engine, farthest away from the water pump, it's imperative the coolant level stays constant.

I would suggest checking the coolant level. However, by the time heat becomes intermittent or weak, you should have already noticed the engine overheating due to low coolant. The cooling systems are actually pretty basic, but when they fail, it's always freezing and it's always a pain to isolate the problem. Come back with any questions. Having replaced everything possible in my cooling/heating system, I may be able to help.
__________________
1989 Jeep Wrangler - 4.0 swap, 32" BFG M/Ts, RC lift
1997 Acura 2.2CL
2008 Honda CBR600RR Graffiti Edition
Fenix85182 is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.