13BT AC Compressor question.

[Stone]

I don't know anything about the AC system, and my factory manuals seem to be very vague about the subject...so I'm throwing this one out there in case there's someone very familiar with these systems.

My compressor all of a sudden stopped working. The vacuum idle-up works, but looking at the pulley, it's obvious that it is not engaging and the compressor is not doing anything. My AC blows warm air, and there's no bubbles that I can see in the dryer window. I've had my system pressure tested, and it still has 60 PSI in it (apparently great readings).

Does anyone know what the problem might be? And is it possible to fix this problem without pulling the compressor out, and therefore wasting my R12 (I just had it charged shortly before the compressor conked out)?

If it's definitely the compressor and it needs to be taken off to be serviced, then I'm just going to have the whole system retrofitted with R134...but if I can fix it on my vehicle and keep the R12, then it would save me mucho $$$. Thanks for any help.

 

[lowenbrau]

Hot wire the clutch to make sure it's functioning. Then you'll know which way to work from there

 

[Stone]

Okay...I'll take a gander over to the truck and see what I can do. Thanks for the quick reply, Bruce.

 

[tlcruiserman]

Stone,

I just converted my Bj70 from R12 to R134a it was farely cheap ($40 USD) and took all of 1 hour at the most. Evacuating your old R12 is the most costly thing (if you do it like you are supposed to) other than that the conversion consistes of two new adapters that hook on to the low and high side valves and recharging the system with R134a/oil.

My system was kind of strange it had 65lbs, clutch worked and everthing, however only blew warm air. I evacuated the system after putting on new valves then charged the system and everything worked great, very cold air now.

I did notice as I was charging the system that the pressure switch to activate the compressor is set pretty high mine was between 58-62 to activate, so even though the R134A likes it around 40-45lbs I am running 60 and it works great.

One more thing, I have heard of issues with R134A begin overcharged and if overcharged you will not get cold air either, but I have not heard of that with R12 systems. If you mix R134a with R12 I think the system will not work as well from what I have heard.

Good Luck,

Michael

 

[Stone]

Michael: I have heard that if R12 and R134 were accidentally mixed in a system, the oils are incompatible and would probably eventually precipitate out clogging everything.

So I went out there and looked at the things my manual says I should look for...

The clutch looks clean and I can't see any grease leaking out.

I took apart the Stator Coil connection as per the manual and checked its resistance. The manual says it should be around 3.7 ohms +/- 0.2 ohms at 20 degrees C. It's about 8 degrees C outside right now and I've got infinity. So I'm thinking this is the problem...could this cause my magnetic clutch to stop functioning? Thanks for all the help.

 

[tlcruiserman]

Hmm,

Not sure on the temp being problem I do not work in those low temps anymore. what is the temp inside the Crusier when you want to turn the A/C on? Maybe it thinks is it colder than it can do. If that was the case, to test warmup your cruiser put the Heat on high until it is nice and hot inside the cruiser and then turn on the air and see if it activates.

Cheers,

Michael

Michael: I have heard that if R12 and R134 were accidentally mixed in a system, the oils are incompatible and would probably eventually precipitate out clogging everything.

So I went out there and looked at the things my manual says I should look for...

The clutch looks clean and I can't see any grease leaking out.

I took apart the Stator Coil connection as per the manual and checked its resistance. The manual says it should be around 3.7 ohms +/- 0.2 ohms at 20 degrees C. It's about 8 degrees C outside right now and I've got infinity. So I'm thinking this is the problem...could this cause my magnetic clutch to stop functioning? Thanks for all the help.

 

[cruiser_guy]

Stone, connect the wire from the A/C compressor clutch to power (12v or 24v whichever it takes) there is only one wire. If the clutch closes, you're OK on the clutch, if not, and I'll bet that it won't close, the clutch is toast.
It can be replaced on the truck if you know what you're looking for. You'll need to loosen the 12mm nut holding the outer part of the clutch and pull it off. There will be spacer washers behind there, be careful NOT to loose them as you need them on reassembly. There will then be a large inside spring clip holding the pulley or electromagnet (whichever is next) on and another spring clip holding the last part on. The biggest problem will be pulling the large spring clips off with the compressor mounted. I've done it but it's not easy.
If the clutch does close then the pressure switch would be suspect and for that you need to discharge the system.

 

[Stone]

Thanks Charles. The one wire that I can see is the Stator Coil Wire that I just tested. It's black, and is hooked up to some funky device on my fender, looking like it's grounded though. Is this the wire...? I'm afraid of putting juice through something that is not supposed to have it.

Maybe I'll take a pic and post it up.

 

[Stone]

Here's a few pics I snapped if it helps any...

Front view of my compressor. The pulley in front doesn't turn with the belt when I turn on the AC switch...

This small rectangular plug on top of my compressor, just behind the pulley is where the Stator Wire goes into. There are two wires, the arrow points to the stator wire...another short black wire looks like it's grounded to the compressor body.

This is the Stator Wire harness which I unplugged to test the resistance of the Stator Coil as outlined in my FSM. I get a reading of infinity (supposed to be 3.7 ohms).

This is the vacuum switch device that the stator wire is connected to. The arrow points to the stator wire, and the white wire with the black stripe is connected to ground.

And this is where the device sits on my right fender wall, just in front of my PS reservoir.

Again, thanks for the help.

 

[silvercrusher]

Have you applied power to the VSV from the battery and tried to blow through it. May just need a little wack with a hammer.

 

[silvercrusher]

Oh ya the resistance between the two contacts on that vsv is roughly 40 ohms @20C. Usually if the clutch is faulty there is alot more of a mess than i see in your pic

 

[cruiser_guy]

Stone, I don't have the funky box on my fender just the same wires at the compressor though. Put power through the wire from the compressor to the funky box. If the front pulley then begins to turn the clutch is OK, if not ....
Clutch failures, as others have said, is not uncommon. You may have a problem if it's 24v though.

 

[silvercrusher]

The funky box is called a vacuum switching valve VSV and is directly linked to the clutch if it isn't operating properly then no compressor clutch power.

 

[Stone]

Thanks for the help guys...Charles, you're right about that wire. I disconnected that harness and put my voltmeter to it. It puts out (therefore my compressor receives) +24V when I turn the AC switch on, and zero volts when it's off.

Also, I traced the two vacuum hoses that goes in and out of that funky vacuum switch on my fender, and figured out that it activates my AC idle up. One hose comes in from the main vacuum system providing vacuum, and the other hose goes all the way to the other side of my engine and into the thing that pushes on my fuel pump (?) to speed up my idle when the AC is on.

So, I know that that wire is seeing +24V when the AC switch is on...so I guess that it is a clutch failure after all. I will check the ground and make sure that it is properly connected...but other than that, I can't see how it could be anything else.

I guess I'm going to be making a purchase at G&S in the next couple of months.

 

[crushers]

stoney, i have one here... dirt cheap... it came off ol smokey and won't be going back on...

 

[Stone]

Hi Wayne...I appreciate the offer and will definitely keep it in mind. I'll email you. G&S has a few kicking around also.

Thanks for the help Wayne...again. My left side FRP window is there intact after some Surrey scumbag broke it thanks to you.

 

[Stone]

Well, finally got to fixing the AC compressor today. In the end, it was the stator coil that had failed. The coil wire was seeing infinity, and the voltage from the VSV was not activating the magnetic clutch because of this.

I swapped in another stator coil that I got from G&S to the comressor while it was still on the vehicle. Thanks to those of you that gave me some tips on this, especially Charles. I removed the front skid plates and the PS and AC belts to give me better access...and actually it wasn't too bad. I would have been done in 1.5h but the stupid little screw that holds the stator ground wire and the wire guide was siezed and stripped. :angry: Had to make my own new ground wire for the new coil.

Fired her up after putting everything back together...and it worked! She still blows fairly cool after sitting so long, and the refrigerant is definitely low because there's lots of bubbles in the sight glass of the AC receiver. There was a bit of wetness (I touched it and it felt just like water) right behind the compressor pulley after I first started it up, and the AC guy who helped me out assured me that this was not a Freon leak and that it was just moisture buildup...I hope so.

Now I can face the summer again...starting to get warm up here. Thanks again, folks.