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Mark VII Climate Control

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Posted by: Black87LSC

I got an '87 Mark VII and when I turn any of the settings on the climate control on the number and the orange lights both blink on and off. Also, even if I have the temperature set to 90 it blows cold air out. I have another climate control dash unit and I think I'm going to swap it, but I'm not sure that thats the problem. Any ideas????

Posted by: Sifrino3

Try cleaning the plug hook ups. I always found that it helps alot.

Posted by: Pepsi2185

Could be a blender door actuator.

These 4 doors are each driven by a DC motor with a feedback wire to tell the computer which position each door is in. Think of these systems like the throttle position sensor in your EFI system, as they work on the same principle.

Now, with the proper knowledge of this system, try diagnosing it yourself. To get an accurate diagnosis, TESTS 1 and 2 need to be done right after each other.

TEST 1: The head unit has a self-test feature that you can use to diagnose just about any problem with the ATC system. Put the ignition key to the "on" position and set the head unit to 90 degrees and OFF. Wait 40 seconds. If the display begins to flash then you have a wiring problem with the blend actuator, a bad actuator, or a bad head unit. If the LED light begins to flash then there is one or more of the problems previously mentioned.

Address the problems or continue with the test. After no flashing occurs, set the head unit to 60 degrees and DEF. Again wait 40 seconds and look for a flashing display or LED lights. If there is no flashing, there is no problem with the actuator or circuitry.

TEST 2: Push the OFF and DEFROST buttons at the same time. Within 2 seconds, push the AUTO button. If an 88 is displayed, everything supposedly is fine according to the head unit. If you look below, the shop manual also says the number 9 is fine too. Take it for what is worth, I guess. Any other numbers show a problem with the ATC system. Now is the time to write down the number of numbers displayed on the ATC head unit. When you are done with the codes press the COOLER button to put the ATC back into regular mode. The temperature control will now be one degree cooler than what you had set it before running the test. Cool, huh? Now turn off the ignition and figure out how to fix your problem.

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The Codes

1, Blend Actuator out of position, display flashes
2, Mode Actuator out of position, LED flashes
3, PANEL/DEF Actuator is out of position, LED flashes
4, Fresh Air (Vent) Actuator is out of position, display flashes
1, 5 Blend Actuator output shorted, display flashes
2, 6 Mode Actuator output shorted, LED flashes
3, 7 PANEL/DEF Actuator output shorted, LED flashes
4, 8 Fresh Air Actuator output shorted, LED flashes
9, No failures found
10,11 A/C clutch is either always on or always off (you can figure this out easily)
12, System stays in full heat (In car temp above 60° for this test to be valid)
13, System stays in full a/c
14, Blower stays at full speed
15, Blower never runs

Posted by: Black87LSC

Thanks a lot for the feedback!

I'll test it out this week.

Posted by: 98lincmk7lsc

Posted by: Black87LSC

The blend door actuator is messed up....... Looked in the shop manual, but it doesn't give a clear description on how to get to it. I know it's mounted towards the middle of the dash, somewhere....... Has anyone worked with these before, and is there a relatively easy way to get at it?? Any hints would be greatly appreciated, as this is my everyday car and I can't have it appart for a couple of days.

Posted by: OldSchool1

Quote:

Originally Posted by Black87LSC

The blend door actuator is messed up....... Looked in the shop manual, but it doesn't give a clear description on how to get to it. I know it's mounted towards the middle of the dash, somewhere....... Has anyone worked with these before, and is there a relatively easy way to get at it?? Any hints would be greatly appreciated, as this is my everyday car and I can't have it appart for a couple of days.

Just make sure to swap it (head unit) with the same year. Only after that would I trouble shoot it.

Posted by: Black87LSC

Quote:

Originally Posted by OldSchool1

Just make sure to swap it (head unit) with the same year. Only after that would I trouble shoot it.

Already did that..... Thanks though

Posted by: OldSchool1

Quote:

Originally Posted by Black87LSC

Already did that..... Thanks though

D'oh!

Posted by: Omega LSC

Yup...i replaced 2 of my head units but still won't do a thing.

only thing im having is my compressor won't spin eather..

Posted by: Black87LSC

I've been busy moving lately, but finally got my parts cars over to the house and took a blend door actuator out of one and swapped it. Everything works perfect and no more blinking lights!!! I got lucky and it was a lot easier to do than I thought it would be. Thanks for the help guys!

Posted by: MonsterMark

I agree. That was a really nice post by Pepsi2185. I am going to PM Joey and have him add it to the Tech section if Pepsi doesn't mind.

Posted by: JoshMcMadMac

Glad it worked out, and was a simple fix!

Posted by: mespock

Quote:

Originally Posted by JoshMcMadMac

Glad it worked out, and was a simple fix!

Isn't that great when it happens - Another Simple Fix from LvC Members !!

!! Damn you guys are great!!!

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