A/C Compressor Woes

[Mynnx]

I finally got my 87 LX 5.0 back to my house, but not before eating a belt in half (lengthwise) and consequently tearing up my hood insulation. The compressor freewheels, as far as I know, when the belt is off. However, even after putting 3 cans of coolant in it today, something is still wrong with it.

Even when the clutch isn't supposed to be engaged (when the AC is off and when the connector's unplugged), the pulley only turns occasionally, and makes very loud clicking noises as if the clutch were failing to engage or something. But, it shouldn't even be trying when it's off, right?

Help me out if you can; I've about shredded through my second belt in troubleshooting it. I'll have the number of the belt they gave me tomorrow, if that will help.

Thanks,
~Mynnx

 

[PuterAmI]

Pull the connector and see if the compressor is getting voltage. If it is, the system is energized probably at the switch for some reason.

When it should be engaged, it sounds as if you either have a bad LPCS or a bad field coil in the clutch.

 

[Mynnx]

Although I don't know what an LPCS is or what a bad field coil involves, I don't think it matters whether it's getting voltage. It still clicks and everything even when the connector is unplugged, when ideally the clutch is just floating.

Of course, I could be entirely wrong; if so, correct me

 

[JRPony]

I finally got my 87 LX 5.0 back to my house, but not before eating a belt in half (lengthwise) and consequently tearing up my hood insulation. The compressor freewheels, as far as I know, when the belt is off. However, even after putting 3 cans of coolant in it today, something is still wrong with it.

Even when the clutch isn't supposed to be engaged (when the AC is off and when the connector's unplugged), the pulley only turns occasionally, and makes very loud clicking noises as if the clutch were failing to engage or something. But, it shouldn't even be trying when it's off, right?

I'm not quite sure what you're trying to say. The clutch is still engaging even with the connector unplugged? This is not possible. And when you say the pulley only turns occasionally, do you mean the clutch? The pulley should always be turning 100% of the time that the engine is running. Maybe it's just me that doesn't understand whats happening.

 

[PuterAmI]

*trying to troubleshoot "clicks and everything"*

I would say that you have a bad clutch. You can "rent" the tool to replace the clutch from Autozone.

An LPCS is the Low Pressure Cycling Switch.
The field coil is what draws the clutch closed on the compressor.

 

[jrichker]

A few simple electrical tests are advised before popping out the wallet to buy a clutch assembly. With the engine running, use a test light connected to the 2 wires on the A/C clutch harness to make sure you have voltage when you turn the A/C on. If the system thinks that it is low on refrigerant, the clutch will not engage (safety feature, keeps you from burning up the compressor due to no oil). There is an aluminum canister on the firewall with a large hose leading to the A/C compressor. There is a pressure switch on it with a 2 wire connector: pull the connector off and jumper the wires. The compressor circuit will power up, and the test light will light if the electrical circuit is good. This test is also a good way to check the compressor & clutch if the system is low on refrigerant. You can jumper the wires and the compressor will turn if the clutch is good.

The A/C clutch is about $100 new or you can buy a compressor from the junkyard with a working clutch for about $50. The puller is about $16 if you have to buy one, Autozone will rent you one for free.

The clutch hub is usually what fails, the rubber shock damper shears off from the steel hub and plate. The pulley turns, but the hub doesn't when you power up the A/C The hub comes off without much problem if you have the puller. You don’t have to do anything with the refrigerant (R12 or R134a), you can replace the clutch without draining and refilling the system.

 

[Mynnx]

Hrm..Perhaps I should describe my problem a bit more accurately. When running (AC on or off) the pulley randomly stops turning altogether, and the belt slides right over it. Occasionally, it will turn a few times, and then lock up again. When it begins to turn though, a loud clicking noise can be heard. Most of the time, though, it is not turning.

Yesterday I tried jumper-ing the wires by the canister, jrichker, but it had seemingly no effect. When you say that the "pulley turns, but the hub doesn't", is this something that you can see? My pulley isn't turning, so I don't see how that helps me...

Thanks guys; keep 'em coming!

 

[jrichker]

It sounds like either the unit is overcharged (2 - 2 1/2 cans for a full charge) or the compressor is fixing to die.

 

[JRPony]

Hrm..Perhaps I should describe my problem a bit more accurately. When running (AC on or off) the pulley randomly stops turning altogether, and the belt slides right over it. Occasionally, it will turn a few times, and then lock up again. When it begins to turn though, a loud clicking noise can be heard. Most of the time, though, it is not turning.

Yesterday I tried jumper-ing the wires by the canister, jrichker, but it had seemingly no effect. When you say that the "pulley turns, but the hub doesn't", is this something that you can see? My pulley isn't turning, so I don't see how that helps me...

I think I get what you're trying to say. But you're misusing the terms here. The pulley is what the belt is riding and is spinning (freewheels) 100% of the time. If it wasn't then you would hear a loud screech from the belt. The clutch, or hub as some people have called it, is what actually turns the compressor and is the big plate on the front.

It sounds like the compressor is cycling on and off either due to an undercharge/overcharge or something that is causing too much pressure. The loud clicking your hearing with the A/C on is probably your compressor running with no oil. No offense, but it appears that you lack the knowledge in HVAC systems to repair the problem. That, and coupled with the fact that is near impossible to diagnose anything over the internet, I would suggest, if you really want it fixed properly, to take your car to a professional.

 

[90mustangGT]

I have to agree with JRPony, maby you need to take it to a professional. Everyone thinks that everything automotive is just common sence, and yes some of it is, but much of it isn't.

 

[Mynnx]

JRPony, I admit that I do lack an in-depth knowledge of HVAC systems - but when I talk, I know what I'm saying. The pulley does lock up, in fact, and the belt squeals; I just thought that was apparent. I would suggest that it may be a bad bearing, but it only seems to lock up when a belt's spinning on it.

I plan on taking it in; this is stupid, especially with the parts stores giving me the wrong belts. WTF am I supposed to tell them when they ask me "Dealer or factory installed" if I'm not the original owner and don't know? - They don't even know what it means.

Anyway guys, thanks!

 

[JRPony]

It seems that you didn't make that fact apparent. Everyone who responded suggested a problem with the clutch or a refrigerent pressure problem, both of which have no affect on the pulley.

If your pulley is locking up, then no matter how many belts you throw at it or how many cans of refigerent you dump in, you will still get the same result - shredded belts. I'm not quite sure about the availability of just a pulley bearing; you might just have to replace the whole clutch assy which includes the pulley.

 

[Scorcher2005]

i have a whole ac system for sale ;-)

 

[JB66]

After having read through this thread, let me see if I got this correct... With the engine running and the a/c system completely turned off, the pulley on the a/c compressor is making a clicking sound. Occasionally, the pulley stops and the belt squeals, which in turn eventually destroys the belt. Am I correct? Or is it that with the engine running and the a/c, mix or defrost is turned on, the pulley stops when the compressor clutch tries to engage?

 

[Mynnx]

JB66, to answer the first question in your post, you are correct. The controls in the cabin seem to have no bearing on when the compressor acts up.

 

[JB66]

Something in the wiring is messed up. Disconnect the connector at the compressor clutch and see if it still acts up.

 

[jrichker]

Something in the wiring is messed up. Disconnect the connector at the compressor clutch and see if it still acts up.

Very good idea, follw his advice. If it does it without the wiring connected, the clutch pulley bearing is bad.

If it only does it when the center hub is turning & the clutch is powered up, the compressor is fixing to take a dump. When the compressor dies, you have to flush the system to get the metal circulating in the system flushed out. If you don't then the metal left in the system will destroy the new compressor.