Warning: lots of quirky electrical gremlins in the following post that might make you want to bang your head on something.

02 Ex 4x4 Limited 7.3L, 180k miles

So I had the air out the defrost vent problem for a while, couldn't find any vacuum leaks (although I don't think I looked hard enough). I took a shot and replaced the seals in the front hubs. No fix. It came time to do my 30k coolant and tranny flush so I took it to the dealer and told them to look into my AC problem. They came back and said it was the pump. I thought that was weird because I could hear the pump come on and run every time I cranked it, but I was tired of trying to figure out the vent issue and it was getting hot outside and so I said Ok fix it.

The new pump seemed to fix the problem, air came out the right vents and worked fine for the last couple months.

Then just the other day, we had a torrential downpour (this may or may not be relevant, I just don't know). I think it may have been the very next time I drove it I noticed I had no blinkers. The day after that, while driving, I noticed my radio went out and my windows wouldn't work, and my overhead console display went blank, AND all air is coming out the defrost vents again! and the REAR AIR system stopped working completely, no air coming out the rear vents at any fan speed.

The radio and windows came back on, but I still had the other problems. Meanwhile, I started going through some of the fuses, checking the ones I think would control any of this stuff. I read something about the instrument cluster, battery saver relay, etc...and I think that caused my radio and windows to go out and that problem will probably continue to happen with more frequency until I get my cluster swapped/rebuilt (which I will use Circuit Board Medics for-they are a great business and very knowledgeable on the subject).

I still had the problem of no turn signals, no overhead display, no rear air, and front air out the defrost vents only.

After doing my usual reverse diagnosis by replacing the flasher with a new one from Advance, then replacing the turn signal switch with a new Ford part off ebay, to no avail, I then finished going through ALL the fuses and finally I get to Fuse 27, Ignition Switch Run Feed, 15A, and its blown! I replace it and voila! My turn signals work again, my overhead display is back on, and my rear air system works again!


But I still only have my front air coming out the defrost vents. My old pump I could hear working and now I don't hear anything, but I read that the new pumps are quieter, so maybe its working and I can't hear it. I want to check the fuse to be sure thats not it but I don't know which fuse that pump is on. Which is it?

I also think its strange that all this stuff happened at the same time, shortly after a very hard rain, but at least a couple of these things are unrelated to that. It seems that the instrument cluster thing is inevitable, and it just had to happen at the same time as this other stuff, after a torrential rainstorm, just to make things harder for me I guess. (Somewhere along the way I also noticed that the rubber boot going from driver door to firewall that covers a bunch of wires wasnt fully seated and maybe water got in there.)

And when I say I checked the fuses, I mean I looked at the blade type fuses and the cube shaped ones and couldn't see where the wire was broken. Im basically inept when it comes to an ohmmeter, so if its one of the relays in the fuse box that control the vacuum pump/4WD system?, Ill need to figure out how to check those.

Sorry for the long post, I wanted to be thorough and put everything in there that I thought might be related in order to get accurate replies.

Thanks for any input!

 

Did you look in your owner's manual to see which fuse does what?

 

Yes. The owners manual does not list everything that is associated with each fuse. For example, fuse #27 is labeled Ignition Switch Run Feed and controls a myriad of things, one of which is the Turn Signal Relay (there is another fuse for Turn Signals). Anyway, I have determined that it was Fuse 27 that powers the vacuum pump, but I am now looking for any relays associated with the pump, because its not turning on.

 

Sounds like you are doing a good job of tracking things down so I will leave you to that.



I will just add, get one of these handy fuse checkers at the auto parts store ( they are next to the fuses and cheap ) and throw it in your glove box with the spare fuses, makes checking and finding the blown fuse easy to find when you are on the side of the road. A real test light is another good item to carry in your kit But the fuse checker and a fuse puller is easy to show the wife how to operate if you happen to have one of those units who may drive the Ex.

 

There's no relay for the pump, it's a direct feed from F27.

If the lt blue/pink wire at the pump connector is hot (in RUN only) and the black wire is grounded but the pump isn't running, the pump is bad, regardless of how old or new it is.

 

10-4, thanks guys

 

I just listed the fuse that feeds the vacuum pump in another post about the heated seat problem. Fuse 2.27 along with a long list of other stuff.

 

Stu, did you ever figure out your AC issue. I have the same issue with Blinker, Reverse Sensor and the AC coming through the defrost that seemed to all happen at the same time. .I Replaced the turn signal and the flasher with no luck. Had a friend do some rewiring to get blinkers to work. He thought the AC issue was a 4wd solenoid. I just installed that part and still didn't work and then found this thread. Sure enough, fuse 27 was blown. I replaced that and my reverse sensors started working. It probably would have fixed my blinkers. But... still a no go on the AC. It's still coming through the defrost vents. Any ideas????