Quantcast F250 heater issues - Ford Truck Club Forum




Home






Forum






Gallery






Garage






Blog






Arcade






Settings






New Posts






TOTM






Vote




Remember Me?
       Join for free!




Search






How-To's






Unanswered






FTC Toolbar






Social Sites






Register




 
Ford Truck Club Forum > FORD F-250 | F-350 SERIES | SUPER DUTY > 1992-1997 Ford F250 | F350



Welcome to FordTruckClub.net
Welcome to FordTruckClub.net, the internet's premier Ford truck community! You are currently viewing our boards as a guest which gives you limited access to view discussions and access other forum features. By joining our free online community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple, and absolutely free so please, join our community today!

Forgot your password? click here.

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

 
Thread Tools Display Modes
  #1  
Old September 15th, 2018, 08:57 PM
douglaswstokes's Avatar
douglaswstokes douglaswstokes is offline
 

Join Date: Sep 2018
Posts: 6
Likes : 0
Liked 1 Time in 1 Post
Default F250 heater issues

This is the second Ford truck I've owned in my life, first being an old F150 with a 3-on-the-tree. Ah, back to my younger years....

At any rate, I needed a truck to get firewood and was a flatbed, 4wd, 3/4 ton, manual trans with a V8. I found a 94 F250 that had all of that, but needed some work. Got all the mechanical issues dealt with, but I could never get any heat from the heater. The gauge never raised hardly at all, so I changed the thermostat - to no avail. I checked the voltage from the computer and found it was fine. I checked the resistance on the sensor as the engine heated up and it also worked fine. I put a temp gun on the engine side of the housing and saw that the engine did heat up and that my new thermostat was working fine, but still nothing on the gauge. I crossed over the wires in the connector that should have sent the gauge to hot, and found that to be the problem. Used temp/oil pressure gauge coming from ebay.

Got heat to the core because the core cover gets warm. The temp control switch is hooked up and works. The fan works fine but no air movement from the vents. Confused.

But there's a vacuum servo mounted on the heater blower housing that had a compromised vacuum line. Don't know what that switch is for, but I believe it's what allows the air from the heater motor to enter the duct system. What activates this servo? BTW, where can I get the vacuum line that's used here?
Attached Images
 

Last edited by douglaswstokes; September 15th, 2018 at 10:20 PM. Reason: spelling
  #2  
Old September 15th, 2018, 11:02 PM
glc's Avatar
glc glc is offline
 

Join Date: Jul 2012
Location: Joplin MO
Posts: 1,137
Likes : 2
Liked 112 Times in 108 Posts
Default

We are having some forum issues, your attachment is blank.

Yes, it's called a blend door, and it's vacuum operated. If it's a small hard plastic vacuum line, just cut out the bad section and splice it with regular vacuum hose. You can test the servo and the door by applying vacuum with a hand pump and see what happens.

2003 F-150 XL RCSB 2wd 4.2 5 speed 3.55 LS
  #3  
Old September 16th, 2018, 04:56 PM
douglaswstokes's Avatar
douglaswstokes douglaswstokes is offline
 

Join Date: Sep 2018
Posts: 6
Likes : 0
Liked 1 Time in 1 Post
Default

What actually supplies the vacuum from inside the cab?
  #4  
Old September 16th, 2018, 04:59 PM
douglaswstokes's Avatar
douglaswstokes douglaswstokes is offline
 

Join Date: Sep 2018
Posts: 6
Likes : 0
Liked 1 Time in 1 Post
Default

What in the cab directs the vacuum to the blend door?
  #5  
Old September 16th, 2018, 05:42 PM
douglaswstokes's Avatar
douglaswstokes douglaswstokes is offline
 

Join Date: Sep 2018
Posts: 6
Likes : 0
Liked 1 Time in 1 Post
Default

Until I figure out what routes the vacuum to the blend door servo I just zip-tied it open. At least I get some air movement.
The Following User Likes This Post:
  #6  
Old September 16th, 2018, 07:45 PM
glc's Avatar
glc glc is offline
 

Join Date: Jul 2012
Location: Joplin MO
Posts: 1,137
Likes : 2
Liked 112 Times in 108 Posts
Default

The control unit in the dash is connected to a vacuum source through an accumulator and check valve. The control unit controls the vacuum to the blend door servos.

2003 F-150 XL RCSB 2wd 4.2 5 speed 3.55 LS
  #7  
Old September 16th, 2018, 10:04 PM
douglaswstokes's Avatar
douglaswstokes douglaswstokes is offline
 

Join Date: Sep 2018
Posts: 6
Likes : 0
Liked 1 Time in 1 Post
Default

The temperature control knob. Thanks.
  #8  
Old September 16th, 2018, 10:21 PM
glc's Avatar
glc glc is offline
 

Join Date: Jul 2012
Location: Joplin MO
Posts: 1,137
Likes : 2
Liked 112 Times in 108 Posts
Default

Not only the temperature control knob, but I think the mode selection (floor, defrost, etc.) is also vacuum controlled. At least it is on my 2003 F150 with manual A/C. It has to open and close doors. Older systems may still use cables for this.

2003 F-150 XL RCSB 2wd 4.2 5 speed 3.55 LS
  #9  
Old September 17th, 2018, 12:19 AM
douglaswstokes's Avatar
douglaswstokes douglaswstokes is offline
 

Join Date: Sep 2018
Posts: 6
Likes : 0
Liked 1 Time in 1 Post
Default

checked the servo with a vacuum pump and it works. Replaced the broken section with vacuum hose. Fired up the engine and turned the heat control to hot and voila. Thanks, guys.


Thread Tools
Display Modes


(View-All Members who have read this thread : 6
douglaswstokes , FrankCoosy , glc , harrison28 , JSoko , KeithFoult

Similar Threads
Thread Thread Starter Forum Replies Last Post
1979 F250 electrical issues HackNtheBox 1948-1986 Ford F250 | F350
10 August 24th, 2013 10:44 AM
'95 F250 4x4 slave cylinder issues... 1977 F-250 4x4 Custom 1992-1997 Ford F250 | F350
3 January 6th, 2013 11:14 AM
04 F250 heater won't work Rcramer 1999-2007 Ford F250 | F350
0 December 12th, 2012 11:44 PM
'77 f250 fuel tank issues woodycv62 1948-1983 Ford F100
0 November 11th, 2012 09:06 PM
Heater Core Klitch 1997-2003 Ford F150
11 September 11th, 2012 05:17 PM

Tags
f250 , heater , issues

Forum Jump









FordTruckClub.net is not authorized, endorsed or affiliated with the Ford Motor Company
or any of their subsidiaries. Ford® is a registered trademark of the Ford Motor Company


Powered by vBulletin® Version 3.8.6 Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.