Climate control panel has no power

Tiny
JOYCE FARLEY SMITH
  • MEMBER
  • 2000 LINCOLN TOWN CAR
  • 135,000 MILES
I have no power to my climate control instrument panel. What would cause this and how do I fix it?
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Monday, October 10th, 2016 AT 4:40 PM

9 Replies

Tiny
CARADIODOC
  • EXPERT
First suspect is a defective control module. Second suspect is a blown fuse.
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Monday, October 10th, 2016 AT 5:21 PM
Tiny
JOYCE FARLEY SMITH
  • MEMBER
Would the fuse I need to replace be under the dash or in the BJB?
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Monday, October 10th, 2016 AT 7:08 PM
Tiny
JOYCE FARLEY SMITH
  • MEMBER
Neither of your suggestions worked. I replaced the control module and checked the fuses. I still have no power to the AC!
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Wednesday, October 12th, 2016 AT 4:47 PM
Tiny
CARADIODOC
  • EXPERT
I don't know what a "BJB" is, but most mechanics have a different approach. We don't have our customers' time to waste by paging through service manuals to figure which fuse to test. Also, on most newer cars there are a real lot of fuses that are labeled as being for a computer, but with no specificity of which circuit is involved. Often that's because one fuse can be involved in numerous different circuits or functions. Instead, we just grab a test light and look at the voltages on each fuse. All of the smaller spade-type fuses have two tiny holes on top for test points. Turn on the ignition switch and turn on any systems you can that are related to the problem, then check for those two voltages on each fuse.

If you find 12 volts on both test points, that fuse is good. If you find 0 volts on both test points, that circuit is turned off, so that fuse isn't related to the problem. You're looking for a fuse that has 12 volts on one side and 0 volts on the other side. That one is blown. You can test all the fuses in a few minutes this way.

Larger cartridge fuses are checked visually but they can be hard to tell sometimes. Those large fuses protect numerous circuits which are each further protected by their own smaller fuses, so if one of those is blown, you'll have a number of dead systems.
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Wednesday, October 12th, 2016 AT 4:51 PM
Tiny
CARADIODOC
  • EXPERT
The next step is to check the power supplies and grounds at the controller's connector. Best is to use a test light. If you use a digital voltmeter, the module should be connected to get more accurate readings.

Terminal 2 is a purple wire and must have 12 volts all the time.
Terminal 16 is a purple / orange wire and must have 12 volts when the ignition switch is on.

To check the ground wire, move the test light's ground clip to a positive source. The easiest to find is the battery's positive cable. Now, the test light will light up when you probe a good ground.

Terminal 3 is a black wire. That is the only ground wire. The test light must light up brightly when this wire is probed and its ground clip is on the battery's positive cable.

If these three wires are okay, that leaves the two data buss wires, and you need a scanner to see if they are related to the problem. You'd have more problems than just the HVAC Controller if the data buss had a problem, but with the scanner, you can see if the HVAC Controller is communicating with the other computers.
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Wednesday, October 12th, 2016 AT 5:44 PM
Tiny
JOYCE FARLEY SMITH
  • MEMBER
BJB=battery junction box
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Wednesday, October 12th, 2016 AT 6:25 PM
Tiny
KEN
  • ADMIN
HI Joyce

I don't mean to but in here but I founds these wiring diagrams for you so you can see each of the fuses and controllers in the system. Check fuse 19, 6 and 2

Please let us know what you find so it will help others.

Best, Ken
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Friday, October 14th, 2016 AT 11:42 PM
Tiny
JOYCE FARLEY SMITH
  • MEMBER
Ken by all means BUTT IN and thank you I'll check those today.
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Saturday, October 15th, 2016 AT 5:36 AM
Tiny
KEN
  • ADMIN
Hey,

Did you ever get the problem fixed?

Best, Ken
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Wednesday, December 21st, 2016 AT 1:49 PM

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