Blend Door Not Swtching

mesundberg1

New member
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Denton, TX
I have a 2000 Lincoln Town Car that recently had the heater core and HVAC actuators replaced. It will not switch from "heat only" mode to A/C. A/C functions well, lines very cold and system fully charged with refrigerant by weight. Is there a re-calibration process that should be performed to correct this issue on the door actuators? Vehicle is also overheating while running: new radiator, hoses, t-stat, water pump, cooling fan assembly, and cooling system was flushed. Proper coolant level and antifreeze/coolant is NEW as well. Please advise to these questions.

Thank you!
 

YoungOldMan

Active member
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I assume all of this work was done at a shop? If so I'd march it straight back there and demand they fix whatever they screwed up so long as these aren't the same exact issues that prompted the work in the first place. If these are the exact same issues then I'd still march back and demand at least a partial refund on labor since they clearly didn't do any proper diagnosis but ripped you off by just replacing a bunch of parts.

That said, there are a few things you can check on your own. First thing, have you tried using the manual settings on the climate controls or have you left it in Auto and just moved the temperature up and down? If you haven't tried the manual modes then try the manual modes. If they work then you can be fairly confident your AC issue is an EATC (Electronic Automatic Temperature Control) problem. If you have tried the manual modes without success, the thing I'd start with is fuses (although that doesn't necessarily rule out EATC issues). After fuses I'd start looking at all of the electrical connectors that you can just in case something was left unplugged. Obviously that's not feasible with the blend door actuators themselves without a great deal of effort, but you can check the other things.

Specifically to your overheating issue, there's a fair to decent chance that when the new radiator was installed and refilled with fluid the system was not properly bled. If you have any pockets of air in the cooling system they effectively operate as blockages and prevent the free flow of coolant, which then leads to overheating. The solution there is to take it back to the shop and have it bled, although you can also do this yourself without any special tools. It's also not at all unheard of for thermostats to be bad out of the box, and since they're pretty cheap you could try replacing it with a new one to see if that fixes the issue.

FUSES
In your passenger compartment fuse box I would check #2, #6, #18, and #19. #2, #6, and #19 all touch the EATC (the thing that controls auto-mode) and #18 is for the climate control module itself.
In the engine compartment I'd check fuse #3, which is for the cooling fan.

CONNECTIONS
Pull the climate control unit out of the dash and make sure everything is plugged in to the back and none of the wire are damaged.
Check the pigtail for the engine fan to make sure it's connected and that there's not an issue with any of the wires.
Take a gander at the cooling hoses to make sure there's not a kink in them and that they're securely connected on both ends.
Not really a connection, but it might also be worth popping the serpentine belt loose and checking to make sure the water pump pulley is rotating freely.
 
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