Possible electrical problem

[Maria Mercer]

I have a 2010 Focus. The horn and a/c stopped working at the same time. The compressor kicks on but will not blow and the horn doesn’t do anything. Could these things be related? My regular repair guy could not fix the problem and said it may be an electrical problem. Anyone else have this issue or know what it could be?

Topic

[Mike]

[quote=”hotbiscuit8″ post=189175]I have a 2010 Focus. The horn and a/c stopped working at the same time. The compressor kicks on but will not blow and the horn doesn’t do anything. Could these things be related? My regular repair guy could not fix the problem and said it may be an electrical problem. Anyone else have this issue or know what it could be?[/quote]

Does the horn chirp when you use the remote to lock the car?
If not, then your horn may have gone bad or the electrical connector for the horn isn’t making good contact.
Read through the threads here for more details:
http://www.focusfanatics.com/forum/mk3-focus/327244-horn-not-working-4.html

If the horn still chirps when locking the car, check the following fuses with a fuse tester or test light or just pull each fuse and look for one that’s blown. As for relays, often there is another one of the same relay in the box that you can swap with to see if the problem disappears.
The under dashboard fuse box fuses I’d check are:
#15 , #24 and #37
The fuses and relays I’d check in the underhood fuse box are:
#12 , #14 , #20 and #21C

A good mechanic should have access to online professional databases, such as IATA, Alldata or Mitchell to access horn and blower wiring circuit diagrams.
Obviously, he’s not comfortable doing electrical repairs.
It may be coincidental that these 2 items stopped working at the same time or it could be a control module.
Wiring diagrams for your car would allow a tech to see if these 2 faults could be related.
Perhaps there’s an auto electric shop in town where they will do the diagnostics and repairs, if the fuses and relays are OK.

There was a technical service bulletin issued back in 2010 by Ford about the horn not working if the airbag assembly isn’t properly seated.
It may not be the cause but it’s worth considering, in case all else fails to find the problem.

Please let us know what fixes it.

[Maria Mercer]

Thank you, I will check the contacts for the horn. What about the a/c? It won’t blow and there are a lot of fuses and relays that seem to be related to it. examples from under hood fuse compartment:
* location 12 Blower
* location 13 A/C clutch
* location 16 cooling fan-low
* location 17 cooling fan- high
* location 20 A/C clutch relay
* location 21C Blower relay
* location 30A cooling fan low speed relay
* location 30D cooling fan high speed relay

How can I tell if one of these needs to be changed?

[Mike]

Sorry I didn’t make it clear that these are the first fuses and relays I would check for both problems–the AC not blowing and the horn not working.

I took, ” The compressor kicks on but will not blow ” to mean that the clutch is engaging on the compressor but no air is blowing from the vents inside the car.
All but 1 of the fuses and relays I listed could be causing the AC issue.
Quoting myself, ” [b]The under dashboard fuse box fuses I’d check are:
#15 , #24 and #37
The fuses and relays I’d check in the underhood fuse box are:
#12 , #14 , #20 and #21C[/b]”
The best idea is to test ALL the fuses because they often control things that they’re not labeled for.

Fuse testers and test lights are very easy to use.
You just touch the metal contacts of the fuse tester to the metal contacts of a fuse and, if it lights the light, the fuse is OK.
For a test light–the alligator clip goes on a good ground and you touch the metal tip to first to one side and it should light, then touch the tip to the other side of the fuse and it should light.
If it only lights up at one side, the fuse is blown.

Relays are hrder to test and it’s best to just swap in another one.
Most often the car has multiples of each kind of relay.

I didn’t suggest fuse #13 since you said the AC clutch was engaging but you check it anyway .

The cooling fans are not the fan inside the car–they’re the ones on the radiator to cool down the engine coolant as it flows through the radiator.

One or both radiator cooling fans should come on every time the AC is turned on.

I would think that the clutch wouldn’t engage if the cooling fans didn’t work.

[Author]

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