Hi all. Here's the story. I finally got to take my 04 6.0L camper out. On the way back coming down out of the mountains the outside air got very hot. So I decided to use the A/C. It worked all the way there two days ago. Now blowing hot air. About 5 miles later I got to a town and had to stop at a light. While stopping there's a big truck ahead of me and we'd just come down a grade and I thought I smelled his hot brakes. Then smoke starts billowing out from under my hood. Oh nuts! That's me that smells. Then before I can pull over my A/C starts blowing cold. Smoke goes away.

I'm thinking maybe the belt slipping on the compressor clutch made the smoke but then why didn't I smell it for the last 5 miles? Why does it work fine now. What the heck. I'm wondering if it's going to happen again on my next trip.

Any thoughts?

 

Sorry you didn't get an answer but I'll bump your thread back to the top.

 

A possibility is that the belt tensioner is weak. This could cause the AC compressor pulley to slip when the compressor is loaded.

This would account for the belt smoke with no AC and loss of belt smoke when the AC compressor was able to rotate and the AC started working.

Lou Braun

 

Thank you Lou. I guess it would be good insurance just to put on a new tensioner and belt then hope it never happens again.

 

Keep in mind that I may not really know of which I speak or type on this subject. And I am simply thinking out loud here.

But, when is the last time you had your AC unit charged? Could it be that you are running low on Freon. Maybe if you used one of those DIY A/C recharge its and top off the Freon/oil lubrication it wouldn't hurt.

I have used these kits a couple of times on different vehicles, one of which was my 2006 F250 V10 and it worked great. Easy to do and lighter on the wallet than a shop visit.

 

jonrjen Thank you. Sounds like a possibility. It can't hurt to check the pressures and if they're low add some oil and refrigerant. It was blowing nice and cold before this happened and after too. Now I'll have to find my gauge set.

 

I have not seen it on a Ford, but on my Cummins, there are 2 or 3 fingers that act as springs for the clutch, well half of it is gone, I had checked the oil and fluids on the truck as it had been sitting a while, and fired it up, I saw a little wisp of smoke near the front and looked closer... as the AC would cycle it would engage the clutch, and it would spin up slowly and the smoke was coming from the clutch actually smoking till it engaged all the way, ( since one of the fingers was gone, the corresponding piece of the clutch had come out also, and there was less clutch there to grab and hold.) I checked into the price of replacing the clutch and on it Dodge has an agreement that only they can sell the clutch, and the dealer wants 175 for the clutch, you can get a whole compressor complete for 200, I am going to run it till it quits working and then replace it. It still blows 40* air, so I am not too worried.

My situation aside I would check your air gap on the AC clutch, if it is too great it will work till it gets hot and then quit. I have had that happen on a 6.0 truck I had. Bad thing is the dang thing is at the bottom of the engine, and a pain to get to. Once the air gap was adjusted it blew cool for the entire time I drove it. The new owner says it works great. I had checked the pressures on it, and checked the clutch for power, it had power, but it was not drawn in.

 

Donn. Thanks for pointing out those possibilities. You're right, that compressor is way down there. I'll take a closer look at it.

 

I finally got a chance to look at it closer. From under the truck I can see that the clutch drive pin rubber is gone. Clutch still works but this can't be good. The smoke must have been the rubber burning out of there. I removed the belt and the pulley seems to turn ok with hardly any play.
Right now I'm reading the manual on how to remove the compressor. I read somewhere that if the clutch burns like that it's probably because the compressor was too hard to turn. So I probably ought to replace the compressor too. It's got some oil drips on the bottom of it so it may be leaking from the seal too. Now I'm wondering if I should flush the system too.

 

YES. If your compressor has failed then your entire A/C system needs to be flushed unless you want to do the job again. Of course that's only if your compressor has failed, but from what you're saying it seems like this has happened.

 

If you are wanting to know, just pull the orifice tube out, if it has failed you will find everything you want to know right there... If you pull the system open to work on it, I would replace the orifice tube every time, at around 2 bucks they are cheap, and that strainer will pack full if it has come apart.

Every time I work on AC systems on vehicles that are questionable, I have found the orifice tube plugged up, if it is then, yes flush it, or at the very least blow it out with nitrogen, and pull a good vacuum on the system before you try to charge it.

 

Always replace the orifice tube regardless if the compressor is shot when you have to break open the system. It's cheap insurance and often gets clogged. AC is our life blood here in AZ so this is my experience. Don't forgot the vacuum pump to purge and boil the system.

Also, those diy kits don't show you the high side pressure which you absolutely need to know. Get a gauge set either craigslist or harbor freight can help you, and there are lots of how to's on the net on how to check your pressure and what can be wrong with your system.

That being said, it sounds like your compressor is shot, but at the same time check the clutch and gap and check the high and low pressures and make sure it wasn't something else. Smoke can come from lots of things.

 

Thanks to all of you. The a/c still blows cold so the compressor must still be working. I guess it could be that it came apart inside just partially but still works therefore contaminating the system. Great idea checking the orifice tube. I've already started taking the compressor out so I don't want to put it back together just to get the pressure readings.
The manual says on the 4x4 just to take the tire off to get to the hose manifold on the compressor. Sure looks like it's going to be hard to get to.

 

I have a set of Harbor Freight gauges, for as often as I use them I could not see the need to spend more on them... I recommend getting the extended warranty on the gauges though. I have had to exchange mine a few times due to the high side connection stopping working. Yes you can spend more, but that doesn't mean they work any better. I had to get an adapter to hook up to my refrigerant cylinders though. the ones for Automotive R134 cylinders have a larger connection then normal 1/4" refrigeration cylinders.

 

I finally got the compressor out. That thing is no fun to get to. Then the one bolt that holds it to the block that you can't even see is a different wrench size than the other two. That took a while to get figured out.
So...... I took out the orifice tube and what a mess. Guess the compressor is shot. Here's a pic of the orifice tube.
https://plus.google.com/photos/11804...97327238097257