It's a 2005 E250 with about 175,00 mile. It is my work van and I take good care of it, but a couple of problems have come up. A couple of months ago it started to downshift while going down the highway. It would downshift from overdrive to third gear, and cycle back to overdrive. The overdrive light on the shifter starts to flash while this is going on. I changed out the trans neutral switch (TRS) with no change. Some days it does it constantly, and other days a couple of times. I think it might be a connector or bad wire. I can't find any wiring diagrams online except the websites that peddle information.

The other problem is my AC. It quit yesterday going down the highway. The blower is turning out hot air, but the compressor is not engaging. I jumped the compressor relay and the system is still charged, and still cools the interior. I changed out the pressure switch that is close to the accumulator (next to the battery) with no change. It's going to be 106 today, and this needs to be fixed. Any ideas are welcome.

 

Transmission: I assume you confirmed ATF is at the proper level at operating temperature. OD light flashing means a transmission fault. Have you checked for transmission codes?

AC: Does the AC suddenly blow cold after blowing warm? Check the evaporator temp sensor. It might be going out of range. Double check refrigerant charge and pressures. Low charge can lead to icing which is cold at the evaporator but doesn’t allow enough air to cool the cabin. Sounds like a work van with no rear AC.

Sixto
07 E350 5.4 183K miles

 

If the OD lamp is flashing you have a problem
Check the codes
It could just need a shift lever with the wires inside (that break)
You see if you cannot duplicate the concern just by restarting the truck and playing with the shifter
Pulling the lever back and forth. You see if the light flashes from doing just that in park
Check the codes and if you have the capability, the PID for the OD cancel switch
Good luck

 

The A/C
Might still be low on freon
Just because you jumped the pressure cycling switch and it blew cold
Does not mean the system is charged enough to make the cycling pressure switch contacts close
24 pounds is the cutoff but the switches are adjustable with the screw inside the connector
Your 05 van might have a A/C clutch fuse preventing normal operation as well
Good luck
Replace the switch again with a Motorcraft one?

 

Sorry about the slow replay. I broke down and took the van to a shop. They put in a coil and spark plug for the #1 cylinder. The AC still doesn't work, and the air only blows out of the defrost vents regardless of the position of the dash switch. I also found that I have a signal going to #1 cylinder coil, but the injector is not firing, because the PCM is not providing a switched ground to the injector. The other wire going to the injector is hot, and the tan wire going to the PCM is making good contact to the PCM. Thinking about sending the PCM off to get checked as soon as I decide what comany to use for that.

 

Double check the injector harness?
Check that injector driver wiring back to the processor and check the output at the processor connector
Inspect for loose pins in the processor connector
Interrogate the injector harness with the engine running and a noid light in the #1 injector
I would imagine the shop did all that, but? How much dough did you give them for diagnosis?
How much time did they spend? Do they have any master techs?

 

The shop changed out the #1 coil and spark plug. They charged me parts and 1/2 hr. labor, so I'm not out much on that one. I finally resorted to one of those "ask" websites. I started to text with a mechanic and I did a bunch of tests. I have a set of noid lights, and I get a good signal on #1 coil, and nothing on the injector. The hot wire going to the injector is hot, and the tan wire - going to the PCM is making a good connection. The PCM is not providing the ground/signal to the injector. I clamped my test light to the battery + and the other lead to the tan injector wire (while running), and no flashes. I did several variations of this with no results. The AC is the same. I checked the LP switch, and the HP cut-off switch. The system is charged. I can jump the relay, and it blows cold in the cab. The circuit that triggers the compressor clutch relay is not grounding in the PCM. I have heard that a missfire in this vehicle will cause the PCM to shut down the AC - true?. I started to suspect the crack position sensor, but the Ask guy didn't bring it up when I ask him. I don't like to throw parts at things like this, but I'm thinking about ordering a rebuilt PCM and seeing if that fixes this. It looks like the PCM's for these vans are a common failure item.

 

Good job on diagnosis
I would do the same then
Look for a spare processor (keep yours)
Once found you should have a Ford dealer re flash what is needed for everything to work

 

Here is a follow up. I sent my PCM off to get checked, and the shop said it was unrepairable. I had them send me a rebuilt one, and I put it in today. I was warned that it may start and immediately die, and to get a locksmith or shop to make some new keys. I left the key on (not running) for about 10 minutes and then started the engine. It cranked up and it ran smooth. It ran for 3 or 4 minutes and it started to run a little rough before it died. It died a couple of more times. The overdrive light on the shift lever flashed from the very start, and the AC is still not working. The air only blows out of the defrost vents. Here are the codes: P0351 (again), P0750 Shift solenoid A, P0755 Shift solenoid B. I know it takes a while for the computer to relearn. I only ran it for about 10 min. Should I take this thing out and drive it a little?

 

That's all you can do
Drive it and see
It may work just fine
See the nearest reputable dealer for any reflash it may need