Amnesiac

I will! Don't worry, tomorrow I'm going to figure out the jumper situation and I'll report back with the results.

rrich

If you are happy with it, good!

I've never seen a compressor put shrapnel in the lines, but I suppose it could. A good flushing is always good, if junk was in the lines then you'd see it come out.
You "back flush it.'

The usual compressor failure is the bearings, crankshaft, seals or the clutch.

On the Sanden or Mitsubishi types used on Jeeps it's near impossible for junk to get past the reed valves even if a piston broke apart.

He He - last summer a friend's wife called me. She said her husband took their View to a "shop they've used for years." She said it started making a noise, when she shut off the AC it stopped.

The shop said it "exploded inside" - it would cost $2800 to fix it. Her husband wrote a check for $800 deposit before they'd order the parts. They disconnected the clutch connector so he wouldn't notice it still worked fine.

He brought it to me (I'm retired now, sold my last shop years ago) - it still blew cold air fine, but it did make a noise. The idler pulley bearing was going bad. $30 for a new idler!
It was a fight when he cancelled the check!

Too bad there isn't a death penalty for incompetent or dishonest shops.

Glad it worked for you.

djb383

Plenty more articles out there and maybe shrapnel was a bad choice of words.....sorry, I'm not a mechanic by profession. Hope the kiddo and I did something right on our a/c overhaul. Nobody likes to be taken for a ride but one man trying to boink his fellow man just seems to be the norm anymore (from D.C. down).

http://www.ackits.com/c/BlackDeath/A...+Death%29.html

rrich

That's why this forum - you have the opportunity to ask before taking it to a crook.
Too bad there are so many crooks! But it's the norm these days. Our government sets the example.

Amnesiac

At the risk of embarrassing myself here, could someone explain how to jump the clutch in a little more detail? I have a wire that I can use to jump the clutch from the battery, but I want to make sure I'm connecting everything up in the right place. As I understand it, the low pressure switch is on top of the drier, which is easy enough to find, but the only connection I see near the clutch is on the underneath of the high pressure side.

At this point with the valve replaced and pressure on the system the clutch will engage off and on quickly for two or three minutes until things heat up and then it stops. I've tried increasing the pressure when it's cycling like this, but it will never engage for more than a few seconds. Since I know the clutch is getting power, can I just go straight to checking the low pressure switch?

waltermitty

You can unplug the connector from the dryer and jump the terminals there. Just don't let it run too long as an unsafe pressure will build rapidly. From the dialogue I've read here so far It appers you have a leak in your system. Juping the terminals to run the compressor appears to be a waste of time in my opinion. I would bite the bullet and buy a new air dryer, orifice tube, and condenser at the minimum. If you want trouble free AC for a long period include a compressor and evaporator and hoses.

rrich

Walter uses the shotgun approach (the only thing he left out was a new blower.) Or you could buy another vehicle - one where the AC works. LOL!

Up till now you said the clutch only engaged once very quickly. Now it sounds like the clutch is OK since you say it's cycling. Forget jumpering the clutch at the clutch

(BTW - Just so you know - there's a wire leading from the clutch itself - it usually has a hold-down clamp on it. On or near the compressor is a black rubber connector to disconnect it. Most are only one wire, but some have 2 wires. Jumper +12 volts to the one wire type. On the 2 wire type jumper 12 volts to one, ground the other. It doesn't matter which ones.)

Now disconnect the low pressure switch connector at the dryer - jumper the connector terminals together - a paper clip works great. Squeeze the rubber connector to take it off. If the clutch engages steady, that part is OK. Either engine running or off, it should engage. Even if it has no or too much refrigerant in it, it should engage.

Since now you say it was cycling on and off, that usually means low on refrigerant.

Engine off - check the pressure with your gauge. You should have about 15-20 lbs engine off. If Firestone really charged it overfull, it should read more - if you don't you may have a leak somewhere - it leaked out - or they lied..

With the gauge still connected, start the engine, jumper the low pressure connector again - tell us what the pressure is/was before and after you jumpered it.

I believe the pressure switch on these is a combination switch - either too low or too high it will open up. Have no fear - If there is a major restriction that makes the pressure go too high where it's unsafe it will activate the blow-off valve on the back of the compressor. You'll see refrigerant and oil blasting out. That seldom happens.

As it runs feel the dryer and lines to it - it may start feeling cold! (For encouragement.)

If it continues to run with the switch jumpered, there's only a couple more places that could be the problem - switch, relay and wiring!

Amnesiac

Okay! We have results!

I went out to the Jeep at a cold start and we first just tried it to see what the compressor would do. It clicked on, ran for about 10 seconds, and then clicked off. It clicked on again and ran for a solid 5 minutes, the air in the cabin was cold, all was glorious.

I turned off the AC and when I turned it back on the compressor clutch wouldn't engage. At this point I tried jumping the clutch directly ( http://imgur.com/TwzWh ) and also inside the harness at the low pressure switch. It would arc at the post, but neither way would get the clutch to engage (or make any sounds, no clicking or anything).

Is it possible that the bearing could be worn out? At this point the pressure was still where I left it yesterday (exactly where the cheapo can gauge said to have it for the ambient temperature), so it doesn't seem to be leaking anywhere (at least not during the 6 or so total minutes the compressor has been running since I filled it).

I can go to the Jeep at a cold start and the compressor will engage (usually it cycles on and off, this last time it ran for 5 minutes until I turned it off) but after that I can't get it to re-engage even trying to jump it directly. Could something be getting hot and seizing up?

rrich

Good info!

But I'm not sure what you jumpered and got a spark. Do one jumpering at a time.
If it didn't engage when you jumpered it right at the clutch when hot, and that's where you got a big spark - look closely at that wire going into the clutch - it may be frayed or shorting against ground. Tape it up. If it's not, then the coil in the clutch is history - you need a new clutch.
But - a new clutch plus the tool is more expensive than replacing the entire compressor with a rebuilt - they come with a clutch. Check around, avoid the cheapies.

If you got the spark at the pressure connector there's something shorted in the wiring.

Amnesiac

As far as I could tell we got nothing at all when we jumpered the harness at the low pressure switch.

When we jumpered off the clutch directly (like in the picture) we'd get a good arc and smoke at the post, but no action at all with the clutch. What has me confused it why it seems capable of spinning freely when it's cool, but after it runs for a few minutes it stops.

Like in the video: http://www.youtube.com/watch?v=Ufl8poI0qRQ#t=19s

This has me a little worried when it will spin but occasionally seems to struggle and won't spin fast.

How easily should I be able to turn that clutch plate by hand with everything turned off?

rrich

Hate to say it - but the coil in the clutch has gone bad. It's not common, but not rare either.
Somewhere inside the coil the wire has broken. When it's cold it touches, but it soon expands a little and breaks connection. That's also why it seems to "struggle" sometimes, it's not pulling in all the way.
You might even see powdered iron filings - black dust - around the front of the compressor from it slipping.

The only way to fix the coil is pull off the clutch and replace the coil - if you can find a new one. That requires several tools. Even AC shops don't do it. We didn't either - too time consuming.
The easiest and best way is replace the entire compressor - it will have a new or rebuilt clutch on it.
One from a wrecking yard is "iffy."

Amnesiac

Thanks, Rich. It's definitely bad news, but it could have been a whole lot worse I guess. I don't really have a ton of money tied up in the Jeep so far so when it warms up a little bit more I might have to start shopping around for some compressors. I'm sure the first day it gets up over 80 here in VA I'll get motivated real quick!

Would something like a Haynes manual be a valuable resource for stuff like this? I'd like to have some kind of handy service manual for learning more about these systems, but a lot of people seem to think the Haynes aren't that great.

rrich

Try ebay - there are cd's with the factory service manual - not expensive at all.

Haynes and Chilton home books are worthless.

rrich

Thinking about it - you could get the tool to remove the clutch,
$35? then go to the junkyard and find one identical. Pull it off - you may ruin a couple doing it - then put it on yours.
Then you wouldn't have to recharge the system.

waltermitty

[QUOTE=rrich;1683170]Walter uses the shotgun approach (the only thing he left out was a new blower.) Or you could buy another vehicle - one where the AC works. LOL!

Good point.