hey everyone I have a problem with my 2000 F250 4x4. The a/c started to go out. At first it would work for about 30min. than slowly go to warm. After a couple of weeks it quit working all together. I have checked the low pressure sensor and that has power but no power to the a/c clutch. System is good on refrigerant and all fuses and relays are good. a/c switch on the dash is working. Does anyone have any suggestions. Thanks for the help.

 

Hi hotrodhippi and welcome to FTE!

You might want to start with this:

 

Thanks redford, I'll give this a try but I noticed that in the video he engages the clutch. I have no power to the clutch so it will not engage.

 

What was the outside temperature when you were conducting your tests?

 

around 90degrees

 

You have a PCM-controlled clutch. The series circuit of the cycling and high pressure containment switches serve as an input to the PCM. The PCM, unless operating parameters preclude it, issues a command to energize the A/C clutch relay which, when energized, switches power from BJB F6 to the clutch coil.

The containment switch should be normally closed.

Check the fuse. See if the relay energizes, jumper the low pressure switch,etc...

 

That sounds undercharged to me.

 

Not at all. A low charge doesn't behave that way.

 

Unless the evap coil is icing, no? Those are the symptoms mine had when it was undercharged, anyhow. Of course, it would eventually pretty much stop blowing air too.

 

An iced evaporator will not cause a "no power to the clutch" symptom. Iced evaporators are usually cause by a stuck cycling switch and usually manifest as "reduction in airflow that gets humid".

Low refrigerant charge usually commonly shows up as a short-cycling compressor and insufficient cooling up to the point where there isn't enough static pressure to engage the cycling switch, then it goes completely inoperative. I'm taking the OP at his word that the refrigerant is okay although he might want to expand on that since if it doesn't have enough refrigerant, it also won't have power to the coil.

 

Where did I say an iced evaporator would cause no power to the clutch?

 

You didn't. The OP said he had no power to the clutch with effectively rules out an iced evaporator which is what I was pointing out.

Now, if the OP comes back an re-states the symptoms, then that opens up a number of options which were ruled out due to his initial descriptions.

 

OK, here's my train of thought on it:

Originally, the OP said the A/C worked, but gradually faded over 30 minutes. To me, that sounds like icing caused by an undercharge condition.

Then the OP said after a couple weeks had elapsed the compressor won't run at all.

If there's a leak, that seems like the logical progression of things; now there's not enough pressure to close the low cutoff switch.

Granted, that's purely conjecture since the OP didn't say what the static pressure in the system is, nor what the pressures were when the system was operating. He did say there's power to the pressure switch, but didn't say whether he'd verified it was making it through it.

So yeah, I agree some more information would be helpful.