2006 SD 5.4 born in WY so the AC was probably used a lot. 126k.

I have read the FAQs above and tried to correct this ac problem already.

The system is charged. The clutch gap was too wide and when I took the ac clutch off, and there was only one spacer in there. I removed the spacer and then my gap was too small. Without the spacer the clutch would come on for 2 seconds then go off for about 20.

At this point I still suspected the spacing, so this time I took the spacer and ground it down with my grinder (verry delicately). I put it back together and the spacing is better. The clutch now cycles on for several seconds longer than before, then turns off. Firmly pressing the clutch with a dowel does nothing at all.

With the gauges on the system, when the clutch is engaged pressure builds to the yellow caution zone (45+psi) then the clutch disengages and the pressure drops.

There is no noticeable cooling in any of the above situations. What do you guys think? Could my clutch be shot?

So, what do you guys think? Could my clutch be bad?

 

Wow. A very nice start to troubleshooting this. Nice to see that for a change!

From what I read, you do not have a full set of AC gages, but the simple gage-on-a-can or something like it. Sorry, but those are useless as they don't tell you the whole story. If you have verified the clutch gap as you noted, then odds are on low freon, but it could be something worse too. Start by getting/borrowing a real set of AC gages. You need to know the actual pressure readings from both Hi side and Lo side, plus ambient temperature when you ran the test. We need the stabilized readings with the compressor engaged. Plus the pressure of the system at rest, with the engine off (helps sometimes). Post that info and we can help more.

-Dave

 

Yea, I'm not a fan of the folks who don't use forums as resources first before posting...

Thanks for the reply, and you're right, I used the cheap gauge-on-a-can.

I don't have a real set of gauges and I can't find a place that rents them out. I called autozone and advance auto.

I've recently gained a ton of automotive experience working on late model saturns. I've done several engine swaps, etc, but have never worked on AC.

Do you guys know of another place I could borrow/rent a set of gauges -or- should I just pay the mechanic to diagnose my problem? The simple gap fix didn't work and I'm worried that if I buy new gauges I won't be able to fix it anyway!

Thoughts? Thanks!

 

HF has gauges on sale so I picked up a set for $45.99.

With the truck running and the ac at full I'm getting low side pressure going from -8 to 8 and high side from 25 to 34.

When the clutch kicks on is when the low side goes to - 8 and the high side goes to 34psi.

YouTube - DSCF1689.AVI


The clutch is off for 13 seconds and on for only a couple.

Any ideas?

Shawn

 

What you are seeing is the system cycling due to low refrigerant charge.

On the HF gauge set, the actual pressure scales are the innermost scales on the gauges (in psi) and the outer scales are for temperature comparisons. That's backward from most other gauges I've seen.
I can't make out the readings, but you will notice that the compressor cycles off at about 28 psi. It looks like you're only building up less than 100psi on the high side.
Your system is nearly empty. Look at all of the line connections and crimps for oil or oil/dirt accumulation. If one of the crimps or connections is oily or dirty, you've found the culprit. The oil is carried out with the refrigerant.
If you see oil or oily dirt on the face of the compressor, the problem is likely the shaft seal.
Did you notice any oil behind the clutch plate when you had it off? It should have been clean and dry.

Also, what was the ambient temperature when you checked the pressure?

 

You're right about the psi being the innermost reading. I actually edited my post to show low side pressure of 20-45 and high side of 90-125 psi.

Can I try adding some refrigerant with a can of R134a from autozone or should I take it to the dealer. The dealer wants $50 to even look at the truck.

Ambient temp is about 80°F

Thanks for the help!

 

Good start! lsrx101 is right as usual. You are very low on refrigerant. That means only one thing: you have a leak. Now the question is: How bad?

Sometimes systems can leak over winter if they are never used and the seals shrink a little in the cold. Don't count on being that lucky. If the leak is small, you may find that you need to recharge it every couple years, which may be OK by you. It will not be perfect as your system wil probably get some air in it and you will lose efficiency and maybe things will go bad over time due to corrosion from moisture. That depends on you and your plans for the truck.

The first thing you can do is buy a UV test kit. They're cheap. All vehicles come with UV dye in them from the factory, so all you really need to start is the yellow glasses and the UV light. Put the car in a very dark garage at night, and let your eyes adjust to pitch black for a minute or two. The dye is a very faint glow and not easy to see. Look over all fittings and connections in particular. You may very well not see anything this way, but it is worth a try.

If you find the leak, you can bring it to a garage knowing what the problem is, if you can't handle it yourself.

Otherwise, get a couple cans of 134a (just regular stuff - no leak stop crap) and use your gage set to refill the system until it starts to perform correctly. We can cover that when you get there. There are also a lot of references on the web that can guide you through with pictures and details. Then you will find out how bad your leak is if it dies again soon, or if it works fine for the summer.

-Dave

 

Yes you can BUT, don't use one of the cans with the hose attached. Those contain boosters, sealers, conditioners and other "wonder" chemicals that have no real place in an AC system.
Buy a can tap and get the virgin R134a with no additives, usually on the bottom shelf.
-Screw the tap onto the can and attach the yellow hose to the tap.
- Screw the piercing valve down and back up. This will fill the hose with refrigerant.
-Bleed the yellow hose at the manifold for a couple of seconds. Just unscrew it a bit until it hisses.
-Start the truck, turn on the AC and hold the idle speed at 1500 rpm. Use a helper or get creative with the throttle linkage to hold th engine at that speed.
-AC on Max, high blower and windows open.
-Open the hand wheel for the LOW side to introduce the refrigerant to the system. NEVER open the wheel for the High side with the system running!
-Add refrigerant until the High side pressure is about 1.5 times the ambient temp. (at 1500 rpm). This will get you very close to the proper charge.

This is easy, but you will still have a leak in the system. That's where the original refrigerant charge went and leaks only get worse over time. It would be best to recover the remaining refrigerant, repair the leak, evacuate the system then recharge the proper amount by weight.

Good Luck

Edit: Dave is absolutely correct about the UV dye, I totally forgot to mention it.
I've been working on some older R12 systems recently and they didn't have the dye in them.

 

Thanks for the advice/encouragement. When adding refrigerant, what pressure should I stop adding at? I looked around and didn't find a how-to for my truck, but I'll spend some more time looking.

Shawn

 

-Add refrigerant until the High side pressure is about 1.5 times the ambient temp. (at 1500 rpm). This will get you very close to the proper charge.

The actual pressures in the system will vary with ambient temp, humidity, sun load, engine rpm and airflow over the condenser. There is really no good way to measure the correct charge by watching the pressures. 1.5x ambient on the High side at 1500rpm is a good rule of thumb.
The only way to get the charge 100% correct is to recover the refrigerant, pull the system into a hard vacuum and add the recommended amount of refrigerant by weight.

If you're not familiar with AC repair, I suggest you check out Automotive AC Information Forum - ACKITS.COM . There's a ton of good info in the FAQ section and on the discussion forum.

 

System pressures depend on the ambient temp - that was why we both asked you for it, but your pressures were so low that it kind of didn't matter, unless it was below 40-50 deg.

Edit: And lsrx101 is right again, of course. To do it accurately, you need to evacuate and add a measured amount. But in many cases you can get "good enough" the crude way. You will be able to tell when it is getting better as the clutch will go from cycling frequently to holding in for much longer periods.

Here's the Charts:

 

Thanks for the help.

I'm starting to understand ac systems a little better now.

Here's my plan of attack:
1. Add dye to find the leak. Identify and either repair or take to a mechanic.

2. Evacuate the system using this vacuum pump: - Harbor Freight Tools - Quality Tools at the Lowest Prices

3. Add the correct amount (by weight) of refrigerant.

I think this should get my cool factor back where it's supposed to be!

 

I knew exactly where that link went before I opened it.
As tempting as they are those venturi pumps don't pull enough vacuum for AC work, even with a High CFM commercial compressor. You need to buy, rent or borrow one like this:
Save on Mastercool 90062-A at ToolTopia.com
Check with your local Auto Zone or Advance Auto Parts and see if they have one in their tool loaner program. Many AZ stores in my area do. ( BTW, $105 + free shipping is a great deal for that pump. They're usually about $130 + shipping).

You won't need to add dye to the system, it's already in there. The Leak Detection kit has the light and the glasses you will need to see the leak, though.
Look closely at all of the AC line fittings and crimps, the condenser, and the compressor body and shaft seal. You'll need to pull the clutch plate off to thoroughly check the seal.

Here's something I often recommend to anyone who wants to do their own AC work:
Automotive Air Conditioning Parts & Equipment - WWW.ACKITS.COM: Do-It-Yourself (DIY) Starter and Advance Kits

The $300+ price tag may choke you up at first glance. You won't save any money on your current repair. The kit will completely pay for itself on the next repair (wife, girlfriend, kids car). Anything after that will be money ahead.

 

Listen to the man (lsrx101)!

The venturi pumps are good for light vacuum applications, but useless for pumping down AC systems.

But you are right spot-on about AC systems. They are really pretty simple in operation. You just need a couple specialized tools to really work on them.

I know it's another forum (Explorers...) but this is one of the nicest write-ups you could hope to find on working on AC systems:
Recharging your A/C - A-Z - Ford Explorer Ranger Enthusiasts "Serious Explorations"®

-Dave

 

Well I did add some dye to the system and let it run for about 20 mins. I came back tonight with the blacklight and could not find any leaks. I took off the clutch plate but still nothing. The guy from advance did add a small amount of the r134a can with stop leak so I'm wondering if that had something to do with it. He said that the system was fully charged (according to the gauge-on-a-can).

At this point I think I will try adding some refrigerant. A friend works for an industrial lubricants place and she got me a 12 pack of r134a cans (12oz) for $65. This was about ½ the price at advance, even though I had to buy the whole case, so I've got that now.

I also did not buy that cheap HF vac pump, but I did pick up a tap from advance. I think I'm ready to try adding some refrigerant.

Also, can you recommend a good book to get started with? That starter kit had one included, but didn't say what it was. Also, the $300 doesn't scare me as I've been driving the truck for a year and put no money into it whatsoever besides maintenance. I bought the truck last summer with 118k for $9000 cash. It's a great truck.