Automotive Air Conditioning Information Forum (Archives)

slawson2000 on Tue September 09, 2014 7:51 PM

Year: 1987
Make: Ford
Model: Bronco
Engine Size: 5.0
Refrigerant Type: R134
Ambient Temp: 94
Pressure Low: ?
Pressure High: ?
Country of Origin: United States

I'm back. My previous work...

http://www.autoacforum.com/messageview.cfm?catid=2&threadid=17222

http://www.autoacforum.com/messageview.cfm?catid=2&threadid=17615

So my compressor clutch has failed (I believe). It had been squealing for a while but the AC worked fine. Today, it decided not to work anymore.

I believe the compressor is a FS6. The compressor is not engaging and there is some reddish dust all around it. What the electrical plug is attached to (clutch field coil?) is loose and wiggles around. The outer portion of the clutch (clutch hub?) rotates freely.

How much do I need to replace? The clutch? The bearing? The compressor? I believe the clutch.

Also, how difficult is it to replace? From what I have read, it is just removing the bolt on the end of the compressor shaft, sliding off the old and putting on the new - no puller required. Is that correct? I cannot seem to locate a "how to".

Your help is appreciated...

mk378 on Tue September 09, 2014 8:29 PM

Yes the plug is for the coil. If it is loose or burnt, the compressor will not engage. Check that voltage is reaching the coil when it should be on, and that the coil has continuity (3 or 4 ohms resistance).

No voltage to the coil you should next check the pressure; if all the refrigerant has leaked out the low pressure switch will open and compressor will not engage.

slawson2000 on Tue September 09, 2014 11:31 PM

The plug seems to be okay itself, what it plugs into is loose. I will check voltages tomorrow...

slawson2000 on Wed September 10, 2014 12:07 PM

I checked voltages. Of the two wires in the plug, one has 12v, I assume the other is a ground.

I removed the nut that holds on the clutch, but have not quite figured how to get the clutch off for inspection. Thoughts?

slawson2000 on Wed September 10, 2014 12:30 PM

Oh, and the coil does have about 3 ohms resistance. However, I do not hear/feel any action when the switch is on and I plug it in.

Sorry about the blank posts. I was having problems with the login. I thought I was only logging in, not logging into post. I think I have it figured out.

Also, here are some pictures... You can see where I have rubbed off some of the dust.






Edited: Wed September 10, 2014 at 12:32 PM by slawson2000

slawson2000 on Wed September 10, 2014 8:55 PM

Oh, pressure in the system is about 113psi with the AC off (as it will not kick on).

wptski on Wed September 10, 2014 10:18 PM

Was that with a cold engine? At that pressure the ambient would have to be around 95F or you might have air in the system.

slawson2000 on Wed September 10, 2014 11:28 PM

Coldish engine (I could touch it) and about 93F to 95F out. I am in Las Vegas...

slawson2000 on Thu September 11, 2014 12:17 PM

Also, do I need a puller to get the clutch off or it there a secret? The coil seems loose, like maybe it is not seated correctly...

wptski on Fri September 12, 2014 7:49 AM

Most clutch plates have an internal thread and puller of some type that uses that thread. The coil is behind the pulley and pressed on a hub, its magnetic field pulls through the pulley. If the coil was loose it would/could be rubbing on the pulley when it rotates and you'd hear/feel that.

slawson2000 on Fri September 12, 2014 10:52 AM

No internal threads on the pulley, I think that is used more on GM compressors. Maybe a pulley puller? or am I looking in the wrong place as for why I have no AC?

mk378 on Fri September 12, 2014 11:04 AM

The picture seems to show internal threads in the clutch plate hub, right near the shaft. The special tool puller engages those and then presses on the end of the shaft to force the plate off. Do not try to use an ordinary gear puller on the clutch plate, grabbing from the outside will just bend the plate.

The pulley bearing is held in place by a snap ring that can only be removed after the clutch plate is off. Then you can pull the pulley / bearing assembly with a regular jaw type gear puller. Use a cup-shaped special tool (such as a socket) to span over the shaft so the puller screw does not put force on the shaft. You want the force to be on the nose-piece that holds the bearing rather than going down the shaft to the compressor internals. This is again all after the plate is off because you then need to remove the pulley to replace the coil.

The clutch looks good from the outside, the gap seems proper. You could unplug the coil and jumper it to the battery with the engine off to see if it pulls in. Make sure to connect the + to the proper side because some clutches have a diode that will burn out from using the wrong polarity.

The red stuff is little shavings of iron that normally wear off of the clutch and then turn to rust after they come to rest on the outer parts.

Edited: Fri September 12, 2014 at 11:10 AM by mk378

slawson2000 on Fri September 12, 2014 11:29 AM

There are internal rings(?) on the clutch plate hub, they are not threaded and do not look like they are deep enough to be threads. See picture below

I cannot find a wiring diagram to the compressor. Am I right in assuming that one side of the plug is positive and the other a ground?

I also found a small leak, but it has been there for years as I missed replacing one o-ring on the condenser when I had the system apart. But it is (was) small and only required the refrigerant to be topped off every other year. Does my static pressure sound about right?

I found this diagram of the compressor if it helps.







Edited: Fri September 12, 2014 at 12:10 PM by slawson2000

wptski on Fri September 12, 2014 12:26 PM

The ID of the clutch plate is thread and your pictures shows that. Get/use the proper puller after removing the nut.

slawson2000 on Fri September 12, 2014 5:37 PM

Also, I did jump the coil, it did not engage the pulley...

Ok, time for me to eat crow. I swore those were just grooves, but they are threads. I got a puller, removed the clutch hub, snap ring and pulley. I could not get the coil snap ring off, so I reassembled minus the clutch hub because I have to run out.

I also played with the coil while it was half apart. What moves to engage the clutch? Nothing seems to move. Also the coil does wiggle about 3/32" around the compressor. Should it be tighter?

Am I headed in the right direction? I drive my 3 year old around in this and the 95-100F temps are brutal on the little guy...

wptski on Fri September 12, 2014 6:49 PM

In your diagrams, the clutch hub. Normally called the plate. When the coil is energized it creates a magnetic field. That field draws/pulls the clutch hub against the spinning pulley. If you read the proper 3-4 ohms across that coil, it should pull the clutch hub in. You did have the clutch hub still installed when you manually energized the coil, didn't you? The coil is pressed on and shouldn't move. If it moves forward enough, it could rub on the back of the pulley causing a short but you'd think that would blow a fuse.

slawson2000 on Fri September 12, 2014 7:23 PM

It has +/- 3.4 ohms across the terminals.. I had the hub in, no movement. I had the hub out and tried again to see if something was supposed to move, no movement. No movement visually or by feeling anything.

The coil does not seem pressed on, more like slid over loosely. It basically rattles around about +/- 3/32".

So with the coil energized what moves, the plate or the pulley?

wptski on Fri September 12, 2014 9:35 PM

It pulls the plate against the pulley.

slawson2000 on Fri September 12, 2014 9:52 PM

is the plate supposed to slide somewhat? How does it make contact?

wptski on Fri September 12, 2014 10:39 PM

That triangular piece is spring steel so it flexes in when engaged. When the clutch releases the spring steel brings it back to a position with a bit of a air gap for running clearance between it and the pulley.

slawson2000 on Sun September 14, 2014 10:45 AM

I would also still like to know if I am headed in the right direction... Maybe I should add some refrigerant?

Edited: Sun September 14, 2014 at 10:53 AM by slawson2000

mk378 on Sun September 14, 2014 11:58 AM

Do not add refrigerant. With 115 psi, the compressor should engage. The switch turns on around 40.

If you energize the coil with the pulley off, it should strongly attract any screwdriver, wrench, etc. held near the front surface of the coil.

slawson2000 on Sun September 14, 2014 12:27 PM

One side of the coil it positive (12v) and the other is a ground - correct?

mk378 on Sun September 14, 2014 1:41 PM

Yes. Some vehicles have the grounded side go through a pressure switch or a relay rather than directly to ground though. When you pull the plug and use two wires direct to the battery you will be bypassing all of that.

Edited: Sun September 14, 2014 at 1:42 PM by mk378

slawson2000 on Mon September 15, 2014 1:32 PM

I have to get some better snap ring pliers... and find more time... I will report back.