NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA's Technical Forums > OEM Tech Discussion
Register FAQ Users List Calendar Mark Forums Read
HOME Member FAQ Sponsor Info Rules Donate Bylaws Store Members Chat E-Mail

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #1  
Old December 2nd, 2010, 22:32
hoodwink hoodwink is offline
NAXJA Forum User
 
Join Date: Nov 2010
Location: Seminole, FL
Posts: 15
Heater blows luke warm not hot??

newbie here.. tried the search, but nothing.. so my question is, is this a common issue w/xj's? just picked up a 99xj 4.0 last week and turned on the heat the other day and it doesnt get hot at all?? now, both heater core lines are hot so im assuming the thermostat is ok right? ive been reading that maybe a reverse flush of the heater core might help??

and my last question is, is my jeep supposed to have a "Heater Control Valve"?? looking at teamcherokee's site they have a some for 99-01's.. well, i dont... just 2 lines from the wp/thermostat housing to the firewall... any help would be appreciated thx -Jason
Reply With Quote
  #2  
Old December 2nd, 2010, 22:52
Begster's Avatar
Begster Begster is offline
NAXJA Forum User
 
Join Date: Dec 2005
Location: Cape Cod/Boston, Mass
Posts: 10,498
Re: Heater blows luke warm not hot??

Yes, your heater core is most likely clogged. My '99 and my dad's '01 blow amazingly hot air. Another '99 I got rid of last year didn't blow hot air, and when I parted it out, I found the heater core was completely clogged with junk.

No, you're not supposed to have a heater control valve like the older Cherokees.
Reply With Quote
  #3  
Old December 2nd, 2010, 23:40
RadioShackSpecial's Avatar
RadioShackSpecial RadioShackSpecial is offline
NAXJA Forum User
 
Join Date: May 2009
Location: Michigan
Posts: 271
Re: Heater blows luke warm not hot??

Sounds like someone already tried to flush the core. Probably broke the HCV when taking the hoses off. Its okay to bypass it, just means hot coolant will be running through the heater core all the time (guess not in your case). The blend door separates the hot and cold side so it should not make a difference in the summer.

You could try flushing it but it may need to be replaced. Is Florida not warm? I know here the heater is the first thing I check before buying any vehicle.
Reply With Quote
  #4  
Old December 3rd, 2010, 02:49
Tim_MN's Avatar
Tim_MN Tim_MN is online now
Freakish Hand Strength
 
Join Date: Mar 2003
Location: Minneapolis, MN
Posts: 5,752
Re: Heater blows luke warm not hot??

Newer Cherokees do not have a heater control valve. Low heat can be caused by a lazy thermostat, a clogged heater core, a failing air blend door, or a water pump with a poor flow rate.

Start with a basic cooling system service.

-Use a flushing/cleaning solution and then drain and fill the radiator with a fresh 50/50 coolant and water mix.
-Back flush the heater core with a low or medium water flow from the garden hose. High pressure water or compressed air will ruin your heater core.
-Inspect the radiator for mud/bugs/grass clogging the outside and mineral deposits clogging the inside.
-Replace the thermostat with a STANT or Robertshaw 195* thermostat. Cheap thermostats are cheap for a reason.
-Replace the radiator cap if your Jeep has one. An old worn out cap will allow boil overs and/or allow the coolant flash over into to steam. You will see the coolant temps suddenly jump from 210* to the Red Zone and back to 210* if your radiator cap is weak.
-Replace the water pump. The pumping fins can deteriorate over time and the pump will not flow enough coolant to keep the temps under control.
-Inspect/replace the radiator hoses. Make sure the coiled wire is installed in the lower hose.
__________________
.
.
Quote:
Originally Posted by bimmerjeeper

I spent a few hours researching how to jack up an XJ, but even this is more complex than a normal car.
.

Last edited by Tim_MN; December 3rd, 2010 at 02:52.
Reply With Quote
  #5  
Old December 3rd, 2010, 13:22
hoodwink hoodwink is offline
NAXJA Forum User
 
Join Date: Nov 2010
Location: Seminole, FL
Posts: 15
Re: Heater blows luke warm not hot??

half way through the flush.. went and bought a 195 thermostat and took off the housing and to my surprise, NO THERMOSTAT??? so how would not having one affect the system? was it the cause of no "hot" air? also, flush/reverse flushed the heater core.. looked like chocolate milk... gonna go seal it up, fill, empty, then fill w 50/50.. any steps im missing?

Last edited by hoodwink; December 3rd, 2010 at 14:07.
Reply With Quote
  #6  
Old December 3rd, 2010, 14:21
Begster's Avatar
Begster Begster is offline
NAXJA Forum User
 
Join Date: Dec 2005
Location: Cape Cod/Boston, Mass
Posts: 10,498
Re: Heater blows luke warm not hot??

Quote:
Originally Posted by hoodwink View Post
half way through the flush.. went and bought a 195 thermostat and took off the housing and to my surprise, NO THERMOSTAT??? so how would not having one affect the system? was it the cause of no "hot" air? also, flush/reverse flushed the heater core.. looked like chocolate milk... gonna go seal it up, fill, empty, then fill w 50/50.. any steps im missing?
Chocolate milk is not good, how does your oil look? Has the Jeep ever been overheated? How does it run? I would think about having the engine compression tested and the cooling system pressure tested.

Chocolate milky liquid is usually a mix of oil and coolant, caused by a head gasket or cracked head.
Reply With Quote
  #7  
Old December 3rd, 2010, 14:36
hoodwink hoodwink is offline
NAXJA Forum User
 
Join Date: Nov 2010
Location: Seminole, FL
Posts: 15
Re: Heater blows luke warm not hot??

i shouldve said rusty tea lol.. it was mostly reddish rust color.. oil looks clean, runs perfect, and as far as i can tell never been overheated? so i put it back together and works great.. heat is HOT now
Reply With Quote
  #8  
Old December 3rd, 2010, 14:38
joe_peters joe_peters is offline
NAXJA Forum User
 
Join Date: Apr 2008
Location: Grants Pass, OryGun
Posts: 13,750
Re: Heater blows luke warm not hot??



Now that things are warming up, time for a cold beverage of your choice!

Glad you got it done.
Reply With Quote
  #9  
Old December 4th, 2010, 05:49
yardape's Avatar
yardape yardape is offline
NAXJA Member #272
 
Join Date: Jul 2002
Location: Maryland
Posts: 739
Re: Heater blows luke warm not hot??

I will NEVER buy a car from a hobbyist or shade tree mechanic again. Been there done that with my Grand Cherokee. Its unbelievable how stupid people will be and then leave all their time bombs for the next owner. Congratulations. Glad your mystery was solved.

Not to cast dispersions and I hope its not the case, but be aware that the thermostat may have been removed for a stupid reason,... like the wrong fix for an overheating issue. You'll find out in the summer. Or maybe your jeep just needed a good flush which had been neglected and you took care of.

Last edited by yardape; December 4th, 2010 at 05:56.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Heater Fan only blows on highest setting madska636 OEM Tech Discussion 3 December 31st, 2009 09:07
Heater blows cold and this makes noise xj joey OEM Tech Discussion 1 December 15th, 2009 15:42
I only have luke warm heat - 2000 XJ Sportstr1200 OEM Tech Discussion 6 March 11th, 2008 19:05
Heater fan blows hard on cool but very little on hot Jed OEM Tech Discussion 12 January 5th, 2008 18:15
Heater fan only blows on high WesternXJ OEM Tech Discussion 5 May 8th, 2003 20:29


All times are GMT -7. The time now is 07:55.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014