I'm having a problem with the A/C. When it works, it's nice and cold. But it only works every once in a while. No Rhyme or reason. Just whenever it feels like it, the compressor will turn on. Also, for some reason, my vent adjustment switch stopped adjusting the vents. No matter where I set it, everything comes out of the defroster vents. Before I just start tearing things apart, I figured I would see if you guys have any ideas.

 

for the compressor check the airgap on your compressor clutch, here is a link: https://www.ford-trucks.com/forums/5...ml#post4464164
courtesy of Marv

If the clutch isnt the culprit and you need to replace, PM me, I just replaced the compressor and accumulator on mine.


For the vent control: if you have the electronic shift on the fly 4x4, check the vacuum hoses to the hubs, if not there, start testing the vacuum hoses throughout the system. All the AC vent controls are vacuum controlled.

 

Dan, Will has you covered. I always forget about that air gap issue on the compressor.

 

Make sure the vacuum pump is working also. I just had to replace mine after realizing my fronts werent locking in at the beach and everything was blowing out of the defrost. I found a new pump at BroncoGraveyard for $80 shipped. The dealer quoted me $170.

 

The intermittent cycling of the A/C is a clutch gap problem.

The defrost is a vacuum leak, but not on the ESOF side. Your ventilation setting is controlled by vacuum. If you are always on defrost then you have no vacuum (default vent setting is defrost at 0"). If you had the leak in your ESOF system (to lock/unlock the hubs) then it would only happen shifting into or out of 4wd (for a couple of minutes) then go back to your ventilation setting. The ESOF hub system is controlled by a solenoid that sends a pulse to the hubs.

The vacuum pump and reservior should be on the passenger side just behind the wheel well. You can start there to check your vacuum lines. Unless your vacuum tubing is rubbing on something or in a high heat area then most likely it is worn/cracked at a connection. Since the engine compartment is a more arduous environment than the cab, I would start there (although with vacuum systems you never know). I would gently pull and twist on the hoses at regular intervals to see if there is any noticeabe cracking or damage. If that doesn't net you an obvious leak, then I would recommend borrowing somebody's vacuum pump and start pulling lines and testing the lines and components until you find the leak (if you don't want to take it to a shop). IMHO repairing vacuum leaks is seldom expensive parts wise (it's USUALLY the tubing), it's all in the labor and how much time you want to devote to it.

I don't have any vacuum system schematics and I have only dealt with the ESOF side so I don't have any good place to start .

Hopefully somebody will something more specific for you to help you half split the problem.

EDIT: Even if it wasn't the problem, you might want to check the vacuum pump like mentioned above. With no vacuum, your pump should be running continuously to build vacuum in the system (hence the reservoir to help maintain volume so the pump doesn't have to run all the time). The pump will kick on below a certain level and run until it reaches it's shutoff setpoint (I don't what either of them is, but I'm sure it's greater than 0"). If you are on defrost all the time, then your pump should always be running !

 

Moose, thanks for clearing that up.
I did not realize that the ESOF and vent control were on seperate systems.
However, looking back now that makes plenty of sense.
Good luck with the fix Dan.

 

Thanks for the fast replies. I'm assuming that the vacuum pump it what sounds like a small compressor first thing when you turn on the key. Right?

 

Yeah, I never paid attention to it before so I didnt realize it wasnt working. After I got the new pump on I can really tell. I still need to make sure it is locking the hubs but I have air out of all the vents now. I was getting defrost through all vents all the time, not just when switching to 4x4.

 

It's off of the same system, just different sections from separate controls. There is a solenoid that will open/shut to "pulse" the vacuum to the hubs (it is located above the passenger wheel well and is mounted to the quarter panel). It is just a separate line coming off if the vacuum system that is not always "activated", which is why if you have a leak in that it will only show when you try to lock or unlock your hubs.

Re-reading that it sounds confusing...basically it's all one system. A solenoid controls vacuum to the ESOF portion of the vacuum system (via the switch on the dash) so the system only "pulses" vacuum through that section for about 30 seconds at a time. The reason that it takes a couple of minutes to recover the ventilation from defrost is because the vacuum pump has to re-draw a vacuum on the rest of the system once the solenoid shuts, and that takes a little time.

I hope this helps.

Yes.

 

There appears to be 2 pumps a bigger one and a smaller one closer to the front. I pulled the bigger one, checked the voltage at the connector and got 12v, but it wasn't running, and smelled like it was burnt up. So I'll be looking for one of those. I haven't been able to look into the AC thing yet though. But I did check voltage at the 2 wire connection at the compressor. There wasn't 12v between the 2 wires, but there was 12v measuring from one of the wires to ground. Does that sound right?

 

Hell yeah, AC is working. I thought both problems had the same cause. At least I have AC coming through the defroster vents until I get the new pump. Thanks guys

 

was it the shims in the clutch?

 

Yep it was. Pretty funny though, I dealt without the A/C for the whole summer. I finally get a bug up my butt to check it out and now it cools off to the 70's

 

I did the same thing, been sweatin all summer, finally replaced everything a week ago.
Its still in the 100's here though.
Im not sure when the last time we saw 70...
Congrats on getting it fixed man.

 

My ac started doing that today. Works, but only out of the defrost. I knew it wouldn't take me long to find the same problem in here and get some advice. Now that I think about it I haven't heard my pump running in a while. Guess that's where I'll start. Thanks guys!