No heat coming from heater

Tiny
CHUCKMALLORY
  • MEMBER
  • 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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Monday, October 22nd, 2018 AT 2:45 PM

29 Replies

Tiny
KEN
  • ADMIN
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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Wednesday, October 24th, 2018 AT 11:41 AM
Tiny
CHUCKMALLORY
  • MEMBER
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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Thursday, October 25th, 2018 AT 6:54 PM
Tiny
KEN
  • ADMIN
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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Friday, October 26th, 2018 AT 10:15 AM
Tiny
CHUCKMALLORY
  • MEMBER
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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Friday, October 26th, 2018 AT 3:11 PM
Tiny
KEN
  • ADMIN
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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Saturday, October 27th, 2018 AT 10:28 AM
Tiny
CHUCKMALLORY
  • MEMBER
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, October 30th, 2018 AT 8:40 PM
Tiny
KEN
  • ADMIN
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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Wednesday, October 31st, 2018 AT 11:25 AM
Tiny
CHUCKMALLORY
  • MEMBER
The car only got a little warm when the A/C on and going up a large hill. Turn the A/C off when you started up a hill hard to believe it did not overheat all the time it is driven two and half hours one way to work on Tuesday then the same on Thursday coming home for the last two years. (Never overheated) (Unbelievable) Now can you tell me how to test a ambient temperature sensor the one inside the dash? Thank you!
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Wednesday, October 31st, 2018 AT 2:40 PM
Tiny
KEN
  • ADMIN
They are not giving how to test it just how to replace it, here are diagrams to help. Check out the diagrams (below). Please let us know what you find.
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Thursday, November 1st, 2018 AT 12:57 PM
Tiny
CHUCKMALLORY
  • MEMBER
Okay, heater core is out and new one in. Now putting the dash back together. Here is a tip if you are replacing the heater core when your in the heater box if you cut the metal lines with a hacksaw then pull them through the fire wall it make it a lot easier to remove the hoses from the old core. You do not have to open the A/C system. I was able to do my without opening any lines.
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Thursday, November 1st, 2018 AT 6:49 PM
Tiny
KEN
  • ADMIN
Nice! Good job on not having the remove the heater box, have not seen that done before. Let me know how it goes, thanks for the pictures. :)
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Friday, November 2nd, 2018 AT 11:48 AM
Tiny
CHUCKMALLORY
  • MEMBER
All back together and glad to report, all is well heater gets good and hot. Now if I could only get the sirius radio working again that would be great.
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Sunday, November 4th, 2018 AT 4:50 PM
Tiny
KEN
  • ADMIN
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help.

Please post your new question here, you must be logged in.

https://www.2carpros.com/questions/new

Cheers, Ken
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Monday, November 5th, 2018 AT 8:50 AM
Tiny
MARTDEB
  • MEMBER
  • 1999 LINCOLN NAVIGATOR
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
My car does not heat in front only in back. Can you please help?
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Monday, November 5th, 2018 AT 8:51 AM (Merged)
Tiny
HMAC300
  • EXPERT
It might be blend door actuator but because you have automatic temperature control you have to scan for codes to see what is causing it or not. A mechanic has to do it. You can try pulling fuse for sixty seconds with key on then reinstall it may reset it.
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Monday, November 5th, 2018 AT 8:51 AM (Merged)
Tiny
DANNY CRUZ2
  • MEMBER
  • 1999 LINCOLN NAVIGATOR
  • V8
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
My heater doesn't work in the front only blows out cold air, but works in the back.
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Monday, November 5th, 2018 AT 8:51 AM (Merged)
Tiny
WRENCHTECH
  • EXPERT
With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are both hot, the heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.
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Monday, November 5th, 2018 AT 8:51 AM (Merged)
Tiny
DANNY CRUZ2
  • MEMBER
The friewall inside the truck or in the hood
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Monday, November 5th, 2018 AT 8:51 AM (Merged)
Tiny
WRENCHTECH
  • EXPERT
In the engine compartment is the only place you have access to those lines.
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Monday, November 5th, 2018 AT 8:51 AM (Merged)
Tiny
DANNY CRUZ2
  • MEMBER
So if they're both working I need a actuator
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Monday, November 5th, 2018 AT 8:51 AM (Merged)

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