Ac compressor or clutch?

[91 Plus]

OK,I have my problem in my car down to the ac compressor..When I turn the window defrost on and ac on the both make the same grinding/metal to metal noise! Also when you have either on of them on and you get on it,then there is a big popping noise that you can hear!So my question is do I have to replace whole compressor or just the clutch?And can I do it my self?

 

[sdpatt]

You must determine if the clutch is just slipping or the compressor is seized and the slipping clutch is just allowing the pulley to spin rather than locking and making the belt do the slipping. With the intensity of the metal-to-metal noises you are describing, it sounds like the compressor is locked and the clutch is sacrificing itself to let the engine to continue turning. You shouldn't use any selections on the climate control except OFF, VENT or FLOOR. Any others will try to utilize the compressor and you have already found that to be a bad thing. You will only be doing more damage. Get it checked. Quickly.

 

[Bluto]

Scott,
Will the A/C still cool, and the defrost still blow if the compressor is siezed?

 

[91 Plus]

Yea because the ac still blows just not real cold anymore...It blows nice warm air on the defrost just got that annoying noise!Also I was messing with ac today checking it out and when you rev it up it makes noise around 3000 rpm!!

 

[Darkside]

I think my wifes compressor just took a crap also. I started to see an oil leak below the area of the compressor, and now its blowing warm air. Is the compressor shot?

 

[Bizzy]

BadAss V6's:
I think my wifes compressor just took a crap also. I started to see an oil leak below the area of the compressor, and now its blowing warm air. Is the compressor shot?

Perhaps, but I doubt it. I'm no AC expert, but aren't there are o-rings that are replaced when a compressor is rebuilt? It could be what's bad on her car.

Bluto...if the compressor is frozen the unit won't cool any longer. The defroster may still blow air out (that fan is separate) but it's not going to be air conditioned air.

<small>[ October 16, 2002, 12:15 PM: Message edited by: Bizzy ]</small>

 

[ant-live]

I think my compressor is going too. I doesn't cool but the heat and defroster and everything else works fine. But it makes a sickling noise live metal scraping. Compressor or clutch?

 

[sdpatt]

Please allow me to clear some things up. The A/C compressor has nothing to do with the movement of air inside the passenger compartment. No matter what climate control button you have pushed (except OFF), the air will still be dischared from the selected outlets. Movement of the air inside the car is the function of the electric motor powered, squirrel cage blower beneath the glove box.

There are two things you can choose to do with this air moving inside the car: heat it or cool it. The engine's cooling system, when it's liquid is heated by the engine's combustion of petrolium based hydrocarbon fuel, supplies the heat source to the heater core (a water to air heat exchanger)in the ducting downstream of the blower to raise the temperature of the interior air.

The A/C compressor is responsible for compressing the refrigerant and pumping it through the condensor forward of the radiator (a liquid to air heat exchanger), receiver/dryer, expansion orifice (to drop the pressure to allow the liquid to expand to vapor and get really cold) and finally the evaporator (an air to liquid heat exchanger) inside the interior ducting to cool the interior air.

This cooling effect is also used to remove moisture from the air for clearing the moisture from the internal surfaces of the windows. You must select a temperature higher than the exterior temperature to cause the climate control to use the heater core to also warm the air for purposes of demisting and frosting the windows. This is usually the case when in operation as only the difference in temperatures between the comfortable 70F, or so, inside the car and a lower temperature outside the car will cause the condensation (and possible freezing) of moisture on the glass.

The climate control will still move and heat the air, if selected, even without the operation of the A/C compressor. If your compressor is not functioning properly due to low refrigerant pressure, the low pressure setpoint of the cycling switch will not allow the compressor's clutch to engage in order to protect the compressor from low oil supply conditions at the low pressure. If the compressor or the clutch are physically damaged, you should not use climate control selections other than OFF, VENT and FLOOR.

Another option is to unplug the connector from the cylcing switch to prevent the clutch from engaging. This switch is easier to access than the connector on the compressor itself and is located on the top of the receiver/dryer that is located by the coolant expansion bottle on the 3.0L SHO and above the power steering pump on the 3.2L SHO.

Whatever you do, DO NOT operate the compresor with the noises you are describing. You are only doing more damage and increasing the cost of the repairs.

 

[ant-live]

Whenever, i noticed it, my mechanic unplug the switch so the compressor won't engage. But it makes the noise with the system not on, but still as the belt turns it make the noise.

 

[rangerj]

Ant live,

Scott if you do not mind, I'll take a shot at this one!

If your A/C compressor is not connected, electrically, and is still making metal to metal noise, it is most likely the bearing in the A/C pulley. It could also be the idler pulley bearing, or the alternator bearing, making the noise you describe.

Remove the belt and spin the bearings by hand. Listen for a dry metal to metal sound. A piece of vacuum hose can be used as a stethescope to isolate the sound. A dry bearing will spin more freely than a bearing full of grease, when spun by hand.

If it is your A/C pulley bearing it may be available as a replacement part, depending on the model year of your SHO. The 1989 through 1992 SHOs can get a replacement bearing for about $30.

You remove the nut holding on the clutch face of the compressor. Then pull or pry off the clutch face.

If you do not have access to the required "puller", then use wood shims to pry off the face. The shims are beveled, and if you drive them in between the face and the pulley they will "pry" the face off. Screwdrivers should not be used for this because they can damage the clutch surfaces.

The pulley is held in place by a "snap ring". Remove the snap ring and take note that the snap ring is beveled on the side facing you. It must be installed with the beveled side facing you.

With a little gentle persuasion the pulley will come off, after the snap ring is removed.

On the back side of the pulley there is a wire spring that fits in a groove that holds the bearing in place. This is true for the pulleys that have a replaceable bearing. It is usually stuck in the groove, so gently pry it out without destroying it. Once the retaining spring is out you can press out the bearing.

In the later model pullies the bearing is "pinned" in place. If you can find a replacement bearing for these you can grind away the "pins", and press out the bearing.

Then press in the replacement. I am not sure if the newer model pulley uses the same bearing, but it might.

A "C" clamp with a socket to push on the bearing, and a larger socket to receive the bearing, can be used as a press. So can a bench vice. If you do not have either of these, then take it to your local parts store, who will do it for a small fee.

If your model year SHO does not have the replacement bearing available, you either buy the whole clutch assembly or you improvise.

The idler pulley bearings were discussed in the last 30 days (approximately). It seems that the later model SHO can replace the bearing as a replacement part, but the early SHO cannot.

However the later SHOs use the exact same bearing. All you should have to do is press out the bad bearing and press in a new one. Research the earlier posts to get the bearing numbers, etc.

Lastly, if the alternator bearing is the culprit, check around your area for a shop that rebuilds starters and alternators. For about $60 you can have bearings replaced, and the alternator cleaned up and checked out.

You may as well check the idler pulley bearing for the other belt while you are at it. Hope this helps, rangerj

 

[ant-live]

Thanks for the info. Ironically, i just took my alternator out to replace cause it wasn't holding a charge. I just checked the compressor clutch and it is making the noise.