Mechanics

A/C REQUEST ON ALL THE TIME

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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MarkRC
February 11, 2012.



I think it operated that way all the time but you never noticed before. They do that to remove moisture from the inside air.

Wrenchtech
Feb 11, 2012.
I have no heat up front in any position the climate control is in.

Tiny
MarkRC
Feb 11, 2012.
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.

Wrenchtech
Feb 11, 2012.
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.

Tiny
MarkRC
Feb 11, 2012.
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.

Wrenchtech
Feb 11, 2012.
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

Tiny
MarkRC
Feb 11, 2012.
If the hoses are hot, then you have a blend door problem.

Wrenchtech
Feb 11, 2012.
Even though the air goes where it is directed by the switches? Panel floor defrost all go correctly.

Tiny
MarkRC
Feb 11, 2012.
Again, that has nothing to do with air temp. That is the mode door, not the blend door. The blend door is temo only.

Wrenchtech
Feb 11, 2012.
Thanks, We'll take a look at that again.
Mark

Tiny
MarkRC
Feb 11, 2012.
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