Not a good day for my Excursion.

Drove in to work, and before shutting down, I looked at my EGTs like I always do. Quite a bit higher than normal, and wasn't cooling down as I idled. Waited a few minutes, but it didn't make a difference. Long story short, I seem to have lost power to my above-mirror gauges and the overhead display. Hardly the end of the world by itself.

While researching that issue, and looking at some potential (fuse) culprits, and thinking that it may be the overhead console circuit board, I fired up my Ex and then noticed two AC related issues

1) front AC only blowing out of defrost vents
2) rear AC not working at all (regardless of front AC control position)

The only reason I brought up the above-mirror gauges and the overhead display console is that I don't believe in coincidence.

In an Excursion, if there is a vacuum leak, does the rear AC work at all?

What I've done/haven't done
- I replaced the vacuum hose going to the hubs about 1.5 years ago.
- I have not checked the hubs themselves.
- I have not checked the vacuum pump
- I have not checked the vacuum solenoid
- I did just replace the Ford AIS intake (I craked the lid by closing the hood when the intake lid wasn't properly latched ), so I may have disturbed someting
- I did just replace the heat shield blanket on the passenger side battery

I have a fairly long trip with my familty this weekend going through some hot parts of the desert (Barstow), so above-mirror gagues and overhead display console I can do without, though they would be nice to have. Not having rear AC is a non-starter, especially travelling with our dog.

Thoughts?


thanks in advance,
Herb
'01 Ex, 4x4 (ESOF), 7.3L

 

The front defrost issue is typically related to vacuum. I would start with the vacuum pump since you have a diesel and make sure it is working correctly. If you replaced the rubber hoses down to each hub recently then I would start with the plastic connectors which get brittle and break over time. There are quite a few on these trucks and can take a while to trace them all but you definitely either have no vacuum (pump) or a leak.

The rear AC is not vacuum related and should be enabled as long as the front AC is on. Does the rear fan work at any speed? If it works on high only you could have a bad blower resistor. If it doesn't work at all check fuses - on my 03 V10 I believe it is one of the maxi fuses labeled aux blower vs. rear blower. There is also a relay located in an auxiliary box - either under the dash or under the hood on the driver's side near firewall. I say either place since it seems to have been put in different locations depending on year and motor.

The overhead console has a known issue with them not working. Try this link and see if it helps: https://www.ford-trucks.com/forums/1...splay-fix.html

 

Tried to update via my tablet, but that didn't work

UPDATE

I found fuse #28, the fuse for the vacuum pump was blown. Replaced it with a brand new 15A fuse and the AC operated normally, the rear AC operated normally, the overhead console display operated properly, and my above-mirror gauges operated properly. I was feeling pretty good. Then the fuse blew again.

It also seems that the turn signals don't work if that fuse is blown.

Maybe a short in the pump or solenoid?


Herb

 

Found a burned out backup (LED) lamp. Who knows, Ford does some weird things with their bulbs. Will replace both with incandescent.


Herb

 

Still blowing fuse 28, within just a few minutes of driving.

No surprise.

 

F28 supplies a number of things including the Daytime Running Lamps (DRL), Powertrain Control Module (PCM), Flasher Relay, Reversing Lamps, Vacuum Pump, Heated Backlite Relay, Electronic Shift on the Fly Solenoid, and Auxiliary A/C.

 

I did find one reference in the great-interweb, where if the vacuum pump starts getting old, it tends to draw more current, resulting in fuse #28 blowing.

Anyone heard of this?


Herb

 

Try disconnecting the vacuum pump and see if the fuse still blows. Unless you are turning on the other items on the circuit while driving, this looks like the only one that would cycle by itself.

 

I would disconnect the 4X4 Electronic Shift Solenoid and see what happens. Overtime water gets into the solenoid and will short it out.

Ed

 

I will do this today. The other items (overhead display, above-mirror gauge mount) are always powered when the key is on, so they come on automatically.


Herb

 

Will try this too. I wouldn't think this would be an issue unless the 4x4 was engaged, but I've seen far stranger things happen.

I appreciate the suggestion.


Herb

 

Still blowing fuses with the vacuum pump unplugged.

Still blowing fuses with the 4wd solenoid unplugged.

Still blowing fuses with both the vacuum pump and 4wd solenoid unplugged.

Am going to look at the overhead console circuit board to see if there's a short.


Herb

 

Pulled the overhead console down and looked at the circuit board and didn't see anything obvious. Knowing that doesn't necessarily mean anything, I left the entire console disconnected, replaced the fuse, and just turned the key to the On position without even starting the truck. Fuse blew.

Trying to narrow down the culprits. Looking at the description for Fuse 28, can anyone explain to me what the Trailer tow backup lamp relay coil is, what it does, and where it's located?


thanks,
Herb

 

The trailer reverse lamp is only powered when the shift lever is in reverse. Doesn't match your symptoms.

Checking the schematic, there's a whole lot more on F28 than the brief list I posted earlier.

Without the EVTM, it's going to be tough...

 

That's for sure, but I appreciate your experience and thoughts.

I didn't expect any easy answers, but I did do a check with my ScanGauge, and my TorquePro app, and didn't find any codes.

The search continues.


Herb