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Heater only blows luke warm air

Tiny
VERYCOLD
  • MEMBER
  • 1994 FORD F-250

Greetings, owner complained of no heat. Thermostat was replaced as was heater core. Both lines to the core feel hot. The blend door next to the heater core appears to be functioning properly. I s there another control in the duct system to direct more air into the heater core? Thanks
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Friday, January 29th, 2010 AT 7:19 AM

12 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
There is a tech bulletin on this,It is attached below and guide

https://www.2carpros.com/articles/car-heater-not-working

Check out the diagrams (Below). Please run this test and get back to us.
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Friday, January 29th, 2010 AT 7:57 AM
Tiny
VERYCOLD
  • MEMBER
  • 3 POSTS
Thanks for the info on the blend door cable. I removed the 7 screw cover for access to the heater core. After moving it both with the cable and without it did not appear to close completely. I used a hook shaped screwdriver and was able to reach in and rake the bottom of the plenum next to the door. I heard a rattle and was then able to squeeze my hand in and discover an ink pen apparently had fallen through the defrost and blocked the door from complete closure. After removing the pen and reassembling the door the heater now functions properly and blows 125 degree air.
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Friday, January 29th, 2010 AT 12:21 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Nothin like stayin' warm!
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Friday, January 29th, 2010 AT 1:05 PM
Tiny
CGARTEN333
  • MEMBER
  • 2 POSTS
  • 1994 FORD F-250
  • 130,000 MILES
My heater in my F250 blows cold air. I was going to replace the heater core but when I take the screws out of the plenum I can feel hot air coming out the bottom, so I don't think it's the heater core. My assumption is I have an actuator not functioning properly. Any ideas how I can check this.
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Monday, January 6th, 2020 AT 12:57 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,179 POSTS
Are both heater core hoses getting hot?
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Monday, January 6th, 2020 AT 12:57 PM (Merged)
Tiny
CGARTEN333
  • MEMBER
  • 2 POSTS
Yes
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Monday, January 6th, 2020 AT 12:58 PM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,542 POSTS
  • 1994 FORD F-250
  • 130,000 MILES
My heater doesn't seem to get hot. The AC works fine, but when I switch to heat it doesn't warm up. The temp gauge works, the hoses to the heater core are both warm. I took the cover off the heater core and there is hot air coming out the bottom of the cover. It doesn't seem to blow much air when I switch to defroster either. Any ideas? No matter where I set the knob (floor, vent, or defroster) I don't get hot air. I checked the knob for the heat control and it seems to be working properly.
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Monday, January 6th, 2020 AT 12:58 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Is the blend door motor moving the way it should to allow heat into the truck?

Roy
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Monday, January 6th, 2020 AT 12:58 PM (Merged)
Tiny
JBSILVA2123
  • MEMBER
  • 1 POST
  • FORD F-250
I have a 94 Ford F250 regular cab 2wd. It has the 460 engine and a 5spd. The a/c and heater are not working. I can turn them on but there is no cooling and there is not heating. I am not that concerned with the ac, however I would like to heater to work. Someone advised me that it may need a new heater core. Is this something difficult to change or repair?
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Monday, January 6th, 2020 AT 12:58 PM (Merged)
Tiny
BOOTDOG
  • MECHANIC
  • 665 POSTS
I would try the flushing the heater core first. Remove the heater hoses going to the core and flush out the core with a garden hose.
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Monday, January 6th, 2020 AT 12:58 PM (Merged)
Tiny
FIREHAZ373
  • MEMBER
  • 1 POST
  • 1994 FORD F-250
  • V8
  • 4WD
  • AUTOMATIC
  • 161,000 MILES
I have a heater in the pickup that will not blow warm air into the cab. The thermostat is good and the heater core warms right up and the front passangers feet will get warm fast. But if I try to use the defrost or thed vents all I get is cold air. I have looked all over for debris and I have checked the electrical system. What do I do its cold here and I have small kids.
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Monday, January 6th, 2020 AT 12:58 PM (Merged)
Tiny
DAVE H
  • MECHANIC
  • 13,383 POSTS
FUNCTION SELECTOR VALVE
Place function selector knob in specified position. Using a vacuum gauge, check for presence or absence of vacuum and compare to VACUUM DISTRIBUTION table. If test results are not as specified, check for kinked or broken vacuum lines. If vacuum lines are okay, replace function selector valve. See Fig. 1 .
VACUUM DISTRIBUTION
Selector Knob..Outside/Rec.. Panel/Def..Floor/Def
Position.............Door...........Door..........Door
OFF...................V.................V..............V
FLOOR..............NV...............NV.............V
VENT................NV...............V.............NV
MIX...................NV..............NV............PV
DEF..................NV...............NV............NV
Vacuum (V), No Vacuum (NV), Partial Vacuum (PV).


https://www.2carpros.com/forum/automotive_pictures/266999_vac_6.jpg

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Monday, January 6th, 2020 AT 12:58 PM (Merged)

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