Heater stays on - JeepForum.com

 
LinkBack Thread Tools
post #1 of 5 Old 04-12-2013, 12:38 AM Thread Starter
CRAWLING 98
Wheeler
 
CRAWLING 98's Avatar
1998 TJ Wrangler 
 
Join Date: Aug 2007
Location: SanDago
Posts: 2,545
Heater stays on

My friend has a 98 TJ that blow warm air continually. If he turns up the temp on the heater it gets hotter in the cab (like its suppose to), but when he turn the temp to cool it blows warm. It seems to fight the A/C. I was thinking that it was a bad blend door (not closing all the way). We manually closed it but it still blows warm. I know taking the heater out for repairs is a real PITA as you have to remove the complete dash.

I told him to install a heater core isolation valve on the heater hose to stop the hot water from getting in the heater core. This is a "redneck" fix but might work.

Any thoughts????


Group W Bench
CRAWLING 98 is offline  
Sponsored Links
Advertisement
 
post #2 of 5 Old 04-12-2013, 02:16 AM
JEK3
Web Wheeler
 
JEK3's Avatar
2006 LJ Wrangler 
 
Join Date: Jan 2010
Location: Fredericksburg
Posts: 1,760
May be something blocking the blend door from closing fully. Twigs are common.

You may actually be feeling heat from the catalytic converters coming through the firewall.

I had a similar problem in the summer with the top off. Shoving a towel under the dash in the area above the tunnel gave me some relief.
JEK3 is offline  
post #3 of 5 Old 04-12-2013, 05:42 AM
wesboy
Registered User
1997 TJ Wrangler 
 
Join Date: Aug 2010
Location: Australia
Posts: 391
The OPs friend has AC so a twig wouldn't get past the evaporator to sabotage the blend door but something could have fallen down one of the vents (especially the vent at the top of the dash). I know for sure I've got a nut, a screw and a rubber grommet fall down there - just lucky they haven't messed with the blend door yet.

Pulling the dash is a lot of work just to get some junk out of the heater box.
If your friends 98 still has the original heater core it may be a good time to swap that out to make a big job worthwhile.

To truly isolate the heater core, an isolation valve would be needed on each heater hose. I know it's supposed to flow in one direction but if you put valve on one hose, there's nothing to stop hot coolant running back up the other hose into the heater core.

Or run a bypass hose if you don't need the heater at all.
The inlet and outlet hoses are different sizes - 5/8 and 11/16 - but I'm not sure which is which - both my hoses are marked 'IN'
I ran a short length of 3/4" hose from the thermostat to a brass connector (red arrow), then another length of 5/8" hose around the air intake to the other heater hose connector tube (yellow arrow) which is attached the to the water pump housing.

heater-bypass-2-copy.jpg

I probably didn't need to run the hose around the air intake - was just trying to avoid kinks in the hose.

EDIT: The original heater hoses are in the pic, just not connected.

97 TJ Sport 4.0L Auto RHD
wesboy is offline  
post #4 of 5 Old 04-12-2013, 10:47 PM Thread Starter
CRAWLING 98
Wheeler
 
CRAWLING 98's Avatar
1998 TJ Wrangler 
 
Join Date: Aug 2007
Location: SanDago
Posts: 2,545
Correct me if I am wrong. Does the Cherokee have a three way valve that I could do about the same thing.?

Group W Bench
CRAWLING 98 is offline  
post #5 of 5 Old 06-29-2013, 12:30 PM Thread Starter
CRAWLING 98
Wheeler
 
CRAWLING 98's Avatar
1998 TJ Wrangler 
 
Join Date: Aug 2007
Location: SanDago
Posts: 2,545
It was a bad blend door connection.
thanks for all input.

Group W Bench
CRAWLING 98 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may 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
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome