Have on again off again AC. No correlation I can find. I'm going to check the pressure switch connections when it cools down in the morning. Barring a bad connection, any thought on what would be causing the PCM to kick it out?

Weird part it it kicks in / out on almost the exact opposite of what I would expect.

Start it up and I could have AC, then it will die out. Gets ice cold under acceleration, and dies back a bit coasting, but not always. Out on the road on a long run, when it is out and then kicks in it says on and gets right down to freeze 'em out cold. Make a stop at the rest area and cross your fingers you have AC when you start the truck back up.

Driving in town the other day, 98 degrees of course. I had the windows down and not even a hint of the sounds of the compressor trying to cycle. Then all of a sudden I heard it kick in and pull the RPM's down a little and I had AC for the rest of the drive. Magically I had AC for the drive home a few hours later as well.

I don't have much hair left, and this is going to do a number on them!

 

How do you know the PCM is commanding it off?

 

The first thing I would do is to check the refrigerant pressures on th suction and discharge sides to see if they are correct.

 

Freon appears to be okay, I can't find the high side adapter for my gauges so all I'm checking is the low. And like I said, when it kicks in it runs fine like nothing is wrong. Had a run across the state the other day, three hours no problem other than it seems to cycle out under coasting instead of under power. If it wasn't for the PCM in the circuit I would say that something is backwards... if that makes any sense.

Made a stop in town and nothing, just hot air and no sign of the compressor kicking in. Up and down the hills on the interstate, and about thirty minutes later I felt the RPM drop momentarily and I had AC again.

It wasn't after some bump or something, But I'm going to check the connection on the two pressure switches just in case. I downloaded the wiring diagram, pretty simple setup really. Pressure switches sending to the PCM, fuse and relay on the positive side of the compressor.

Will get into it probably this weekend, right now just looking for some direction. The fun part is getting it to act up sitting in the driveway instead of out between running service calls where I don't have time to diagnose and have to live with the heat until it kicks in.

 

Go check the clutch gap.

 

Will add that to the list of things to check. I would have thought of it right off if there had been any unusual noises from the compressor. But the only 'unusual' noise under the hood is the cam Phasars.

But that made me think of something else, see if I'm way off base here.

What about a bad clutch? If I think about it, it seems to happen when everything is hot. Not the outside temp, but the engine / engine compartment. Starting back up after a short stop and the AC taking a while to come back on. Creeping along in rush hour and it going in and out. But get on the road and get some air flow and it comes on with no problem. Kinda like a starter with a broke wire in the winding. Let it cool off a bit and everything is fine.

Going to have to test it and see if that has any correlation.

 

How does one check the clutch gap?

I've been having intermittent a/c issues for a while.

 

Feeler gauge between the clutch pulley and the clutch 'face'. For my 2005 it's .014 to .030. Anything larger than that and you need to pop the clutch face off and remove spacers to get down to that gap.

 

Been a long time since I had to adjust one, and not with this compressor so I can't tell you off the top of my head if you have to take tension off the belt to change washers.

 

Man I'm surprised I even had AC, the gap was up to around .072! Bad news is there was only one washer in there and I was only able to get the gap down to around .037, spec says .014 to .030.

Will have to get a new clutch assembly soon. Less that $50 on RockAuto so no major there. Does anybody know if the clutch assembly from RockAuto comes with new shims?

I've heard both ways on replacing the coil. Some say let sleeping dogs lie since it's a PITA to get off, others say replace it regardless.

 

You were right again!!

 

Thanks for letting us know!

 

You know what they say about blind squirrels...

They do not. However, you can pick up a hardware pack from your local AutoZone for a couple of bucks that will have what you need. Santech MT0986, IIRC. Around 2 bucks.

I'd stick with the Motorcraft part. Probably a YB-3020 but check it before purchasing, I'm just going from memory.

 

Well I saved the one that I took out so I should be good. Of course it's soooo much fun crawling up under to work on the AC. Would have been nice if it was up on the top.

Going to have to get the pressure washer out and clean things up under there before I tackle that. I think I have a partial can of engine degreaser some where to cut things down a bit.

At lest with the gap down I should have AC until it cools off a bit and I can work outside for more than twenty minutes without feeling like I just crawled out of the shower.

But then that's the norm, working on AC in the heat and the heater in the cold. Kinda like a big joke...

Still not sure about changing the coil or leaving it in place. Guess I'll have to see how much of a pain it is when I try and take it off.

 

https://www.tascaparts.com/oem-parts...y-6f1z19d786aa

https://www.tascaparts.com/oem-parts...l-4l3z19d798aa

http://www.rockauto.com/en/catalog/f...utch+shim,6624