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Heater not working?

Tiny
OUTNLFTFIELD1
  • MEMBER
  • 2001 LINCOLN NAVIGATOR
  • V8
  • 2WD
  • 21,100 MILES
The front heater is not working but the rear is. I have already checked the coolant it is fine.
Tuesday, December 28th, 2010 AT 9:06 PM

41 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
If both heater hoses coming from the heater core are hot, the blend door is NOT moving, if the inlet hose is hot but outlet is cold, the heater core needs more flushing, or replacement. if both hoses are cold, check antifreeze level and thermostat, also rarely but known to happen id the impeller blades on the water pump dissolve over time and may not be pumping enough. This guide will help us find out what's going on.

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

Please run down this guide and report back.
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Monday, November 5th, 2018 AT 8:52 AM
Tiny
COLVARDS
  • MEMBER
  • 4 POSTS
  • 2000 LINCOLN NAVIGATOR
  • 5.4L
  • V8
  • 2WD
  • AUTOMATIC
I have replaced both heater cores, blend door actuator, water pump, thermostat and the climate control. If I let the car set after starting it will warm up like normal but once I drive a couple miles it will start blowing out cold air in the front but remains warm or hot in the rear. Please help!
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Sounds like you are losing vacuum and the blend actuator is closing. I'm sending a diagram so start to check for soft hoses starting at engine it may be sucking together closing he vacuum off or there is a leak someplace.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
COLVARDS
  • MEMBER
  • 4 POSTS
The blend actuator is electronic and the climate control is digital/no nobs just buttons.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
COLVARDS
  • MEMBER
  • 4 POSTS
Oh and before I put everything back together after changing the blend door actuator I made sure it was working properly. As I raised the temperature setting on the climate control it moved untill closed to allow full heat to come thru
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Then get it scanned as one of the potentiometers may be screwed up do this test to see if you get any dtc's then if not have it scanned.
Ensure coolant temperature is at least 120°F (49°C) before entering self-diagnostics. Ensure in-car temperature is between 40-90°F (4-32°C). Simultaneously depress OFF and FLOOR buttons, then press AUTOMATIC button within 2 seconds. Display will show a dashed line in the center of the display window for up to 30 seconds while test is running. Record all DTCs as displayed.
If DTCs are displayed, perform test indicated. See DTC INDEX table. If a condition exists but no DTCs are displayed, go to SYMPTOM TESTS.
Self-diagnostics can be initiated at any time with the resulting DTCs being displayed. Normal system operation is stopped when system is in self-diagnostic mode.
If this has a water valve on the car and it might but we never are shown that, see if hoses stay hot at higher rpm. That is vacuum operated and maybe be screwed up it used to be on eof the big things causeing heat problems on ford products. Here are dtc's and what failure is.
B1249 024 (022)Blend Door Actuator Short
B1249 N/A (025)Blend Door Actuator Failure
B1251 031 (N/A)In-Car Temp. Sensor Open
B1253 030 (N/A)In-Car Temp. Sensor Short
B1255 041 (043)Ambient Air Temp. Sensor Open
B1257 040 (042)Ambient Air Temp. Sensor Short
B1261 050 (052)Sunload Temp. Sensor Short
U1073 (2) N/A (N/A)Engine Coolant Temp. Signal
U1341 (2) N/A (N/A)Vehicle Speed Sensor
might also be a broken blend door shaft as these are known to happen as well. Also the heater care cold be plugged, so try back flushing it, may help.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
COLVARDS
  • MEMBER
  • 4 POSTS
Ok, thank you for the advice. I will try tomorrow and let you know what I come up with. Already tried the back flushing after the problem happened after replacing everything, but again I will let you know tomorrow. Thanks again!
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
JOHNSISON
  • MEMBER
  • 1 POST
  • 2000 LINCOLN NAVIGATOR
Heater problem
2000 Lincoln Navigator V8 All Wheel Drive Automatic

My navigator will not produce any heat. The compressor will run in AC and cool properly. I am not sure if it is a fuse, vacuum or sensor.

Thanks for your help
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check the thermostat, heater core and heater control valve.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
CHUCKMALLORY
  • MEMBER
  • 9 POSTS
  • 1999 LINCOLN NAVIGATOR
  • 5.4L
  • V8
  • 2WD
  • AUTOMATIC
  • 210,000 MILES
No hot air in front or rear of cabin. Both heater hoses are hot to the touch. New thermostat installed. Flushed radiator system and added new antifreeze. The blend door is working properly. The accumulator motor was replaced last year. The only time it starts to get slight warm air is when you push the Vent Button. Do you have any suggestions? Need help!
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
Hello,

It sounds like the HVAC control head is not working right but the be sure here are the wiring diagrams for the system so we can see how it works and to test the ground and power leads. The guide will get us started.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Also lets remove the temperature blend door actuator to see if it moving at all. It could be the ambient temperature sensor as well

Check out the diagrams (Below). Please let us know what happens.

Cheers, Ken
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
CHUCKMALLORY
  • MEMBER
  • 9 POSTS
Hi Ken thank you for your time, The ground and power lead are good. Not sure on how to test the ambient temp sensor. So this is what I have found out so far. Put the EATC module on max A/c temp set to 60 the blend door closes on the heater core. Now turn the temp up to 90 and the door open all the way the air is still ice cold. Now put the EATC to pnl/flr temp set to 60 door closes on heater core ice cold air still now set the temp to 90 door is all the way open still ice cold air. Now set the EATC to vent temp set to 60 door is closed on heater core warm air is coming out now set the temp to 90 the door is open all the way and the air is a little less warm? I used a vacuum pump on the vacuum doors motor all three of them and none of them would hold vacuum should they? Don't know if any of this will help? Now do you still think it is the EATC module? Thank you, Chuck
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
Yes the door do leak a little that is normal. It sounds like the electric blend door is not working right I would try replacing it first. Here are diagrams to helps you. Check out the diagrams (Below). Please let us know what happens.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
CHUCKMALLORY
  • MEMBER
  • 9 POSTS
Can you define "working right"? Are you referring to the temperature, because the door seems to be opening and closing properly. Why wouldn't the temperature change accordingly? I have a hole cut in the housing I can see the temperature blend door moving. That is how I was able to tell you what it was doing in my last email to you. So please tell me why you want me to replace it (blend door actuator) it was replace last year. Thank you again, Chuck.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
I am thinking the actuator because they had problems with them in the shop can you tell me if it was an OEM part it was replaced with? If both heater hoses are hot then it you should be able to remove the actuator and move the door by hand to get full heat. Can you try that?

https://www.2carpros.com/articles/replace-blend-door-motor

Here is a guide to help you see what I am talking about.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
CHUCKMALLORY
  • MEMBER
  • 9 POSTS
Well its not the blend door or the actuator they are working fine. The water pump fins are all gone (gone) the coolant cannot be moving very much. So new water pump. Had the radiator boil out, now get some warm air not hot. Now it heater core replacement time. Thanks for the information.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
DIGGER DAVE
  • MEMBER
  • 6 POSTS
  • 1999 LINCOLN NAVIGATOR
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
I just bought this SUV that is in great condition. The heater was working two days before I drove it away (of course) then when I did drive off all I got was a lot of air throughout the control range and settings but no heat. What could have happened in a two day time frame? I am in Oregon and I need heat! Thank you in advance, this is frustrating.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
  • 1,853 POSTS
First of all, make sure the cooling system is full of coolant, then after the engine warms up and thermostat opens, feel if both heater hoses at the firewall are hot. If one is hot and the other coming back out only luke warm, the heater core is clogged. If they both are just warm, see if there is a heater control valve on either heater hose that might not be opening.
If though both heater hoses are hot, the problem has got to be under the dash and most likely with a blend door, actuator, vacuum hose, etc.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,490 POSTS
Wow good find, usually the engine will overheat when this happens. Here are diagrams to help you change out the heater core. You will need to vacuum down and recharge the AC system.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)
Tiny
DIGGER DAVE
  • MEMBER
  • 6 POSTS
Thank you, I will get on that tomorrow and let you know the results. After forty years of being a "shade tree mechanic" I cannot remember ever having to deal with a heater issue.
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Tuesday, November 3rd, 2020 AT 10:59 AM (Merged)

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