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A/C request on all the time

Tiny
MARKRC
  • MEMBER
  • 2001 LINCOLN NAVIGATOR
  • 114,000 MILES
Just changed front heater core. Now front a/c is on whenever climate control is on (you can hear the compressor engage). Blows cold up front no heat, plenty of antifreeze. Blendor door operates vents fine. Rear heat and a/c are working fine with one exception. In the rear on auto it only blows cold a/c. Other speed settings it is fine (hot or cold).
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Saturday, February 11th, 2012 AT 1:36 AM

16 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,757 POSTS
I think it operated that way all the time but you never noticed before. They do that to remove moisture from the inside air.
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Saturday, February 11th, 2012 AT 2:05 AM
Tiny
MARKRC
  • MEMBER
  • 9 POSTS
I have no heat up front in any position the climate control is in.
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Saturday, February 11th, 2012 AT 2:38 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,757 POSTS
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 not too hot to hold, then you have to look at the actual engine temp and if that is up, if it is, then your looking at a restricted heater core.
If you find that they are both too hot to hold, then 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.
If they are both not too hot to hold on to, then you either have a restricted heater core or the system is not completely full and getting air pockets for some reason.
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Saturday, February 11th, 2012 AT 2:41 AM
Tiny
MARKRC
  • MEMBER
  • 9 POSTS
Heater core is brand new. Rear heat works fine, engine temp is fine. Blend Door works as far as floor/ vent/ defrost. I'll put my hands on the hoses tomorrow. I don't think that is the problem as the a/c compressor stays on no matter the heat setting.
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Saturday, February 11th, 2012 AT 3:12 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,757 POSTS
The compressor means nothing in regards to air temp. You're going to find out that you're wrong about something that you're telling us.
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Saturday, February 11th, 2012 AT 10:44 AM
Tiny
MARKRC
  • MEMBER
  • 9 POSTS
I checked the hoses going into the firewall. They are all warm. It was chilly this morning. No heat up front. Has heat in the rear, heater core is still new. A/c compressor still engages even on hot settings up front, blows cold air up front. I realize I've got to be missing something simple. Besides changing the way the air flows does the Blendor operate the temperature? Could the climate controller have gone bad? I double checked yesterday, but could I have left something unplugged when doing the heater core?
Mark
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Saturday, February 11th, 2012 AT 3:14 PM
Tiny
WRENCHTECH
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If the hoses are hot, then you have a blend door problem.
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Saturday, February 11th, 2012 AT 4:41 PM
Tiny
MARKRC
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  • 9 POSTS
Even though the air goes where it is directed by the switches? Panel floor defrost all go correctly.
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Saturday, February 11th, 2012 AT 4:48 PM
Tiny
WRENCHTECH
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Again, that has nothing to do with air temp. That is the mode door, not the blend door. The blend door is temo only.
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Saturday, February 11th, 2012 AT 5:37 PM
Tiny
MARKRC
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  • 9 POSTS
Thanks, We'll take a look at that again.
Mark
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Saturday, February 11th, 2012 AT 6:30 PM
Tiny
MARKRC
  • MEMBER
  • 9 POSTS
I had the climate control do a self diagnostic. It came back with codes 12 and 49. Any idea what those mean. Press floor and off then within 2 seconds hit automatic.
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Saturday, February 11th, 2012 AT 8:06 PM
Tiny
WRENCHTECH
  • MECHANIC
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Neither one of those numbers are legit HVAC codes. You need to just inspect the blend door actuator and see if it's moving the door or not. I'm suspecting you jammed the door when you put the box together.
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Saturday, February 11th, 2012 AT 8:21 PM
Tiny
MARKRC
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BTW the a/c compressor is not coming on when it shouldn't now (did it reset something). It is still not blowing hot air up front. Isn't is obvious that the door is moving when you switch the panel and the air comes out in all the different places it should?
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Saturday, February 11th, 2012 AT 8:25 PM
Tiny
WRENCHTECH
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I'm not going to continue going in circles here.
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Saturday, February 11th, 2012 AT 8:29 PM
Tiny
MARKRC
  • MEMBER
  • 9 POSTS
I do appreciate your help. I really don't understand about the blendor. That is why I asked the question not stated a fact. Is it a separate piece that you are talking about, or do we know it works if the air is moving to the proper place with the controls? Sorry to frustrate you.
Mark
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Saturday, February 11th, 2012 AT 9:43 PM
Tiny
WRENCHTECH
  • MECHANIC
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I've already answered that question. You're talking about a Mode door and I'm talking about a Blend door.
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Saturday, February 11th, 2012 AT 9:51 PM

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