1991 HDJ81 A/C Compressor noise and slow spin

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I recently replaced the v-belt that runs the Air Conditioning (A/C) compressor on a 1-HDT HDJ81 (1991). I used the correct, OEM belt for the replacement and tried to match the belt tension based on feel. Also, I had a new Denso 471-1433 A/C Compressor installed back in 2017 when the original, factory one finally gave up. The Denso compressor installed in 2017 has been just fine until now. Wondering if my belt tension is off (too tight, too loose?), or if the A/C compressor/clutch is dying prematurely? It makes an odd noise when the the compressor kicks off and the inner part of the A/C compressor pulley wheel continues to go around a little bit in spurts.

I took a short video of the A/C Compressor once it cycles off. Please see below. You can see that the inner part of the A/C compressor pulley continues to rotate ever so slightly while the pulley goes around at normal speed. When the compressor cycles back on, the inner part of the compressor pulley wheel goes at the speed of the pulley. Thanks!

 

jellis

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That's definitely weird. This only started happening after replacing the belt?!?

Belt tension should have nothing to do with that, it's got a whole clutch mechanism. The clutch is probably failing? If you disconnect the clutch connector is there any voltage present with the AC and fridge off? There shouldn't be.

This is worth having for sure:.

Gates 91107 Krikit V-Belt Tension Gauge

 

jellis

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Similar question here:
 
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Thanks @jellis ! I just purchased that Gates v-belt tension gauge, so your timing was impeccable on that suggestion. I don't know if the AC pulley was doing that odd behavior prior to the belt being replaced or not, unfortunately. I will confer with the other 'Mud user to see if his issue is the same as mine. My gut tells me that the AC compressor clutch is probably dying a slow death...which is weird since the whole Denso compressor unit was replaced in 2017.
 
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For what it is worth, I've decided to replace the clutch in my Denso 471-1433 A/C compressor. I'm pretty sure that the clutch is the problem in this case; given the black gunk that is surrounding the pulley wheel, the odd noise, and the weird jerkiness of the inner wheel when the pulley is going around but the compressor is cycled off (i.e. the magnetic clutch is not engaged). I ordered a new clutch kit from AAPAK Coolstream and it should be here in a week or so. I will then attempt to replace the compressor clutch with the A/C compressor still in the vehicle. We will see how it goes :)
 

mudgudgeon

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It would be worth changing the bearing on the compressor shaft behind the clutch at the same time.
It's a $20 part, and can be changed without removing the compressor and without de-gassing the system.
It's responsible for noisy f AC compressor/ckutch sometimes too
 
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Well, the plot thickens. I got the A/C compressor clutch replacement kit in (includes a new clutch pressure plate, assortment of shims, two snap rings, the pulley wheel with bearings, and a new stator/coil) and went to replace the clutch related components. Once I removed the pressure plate I knew something more involved was up... I found fluorescent green compressor oil in the shaft area (I'm pretty sure the green "goo" is compressor oil, right?).

I'm guessing that means that I have a shaft seal leak? Does anyone know if replacing the shaft seal requires you to de-gas the system (i..e remove the R-12) and separate the A/C compressor unit from the vehicle? Looking at the FSM it looks like you need to remove the A/C compressor unit from the vehicle and start digging down into the unit to replace the various seals. Is this an easy task, or is it better left to the experts?

Below is a picture of what the compressor looks like with the pressure plate removed. You can see the fluorescent green compressor oil near the shaft. The A/C compressor still works well, but like my original post states, I think that the clutch/compressor must be on its way out.

AC_CompressorLeak.jpg
 

jellis

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I would highly recommend just replacing the entire unit. Good money after bad here IMO....return the clutch and buy an entire new unit for ~$250. Take it into a shop and have them evacuate the system, replace it yourself (buy a new o-ring kit for $20 and replace all o-rings you encounter), rent a vacuum pump and gauges from an auto parts store and fill it back up yourself. Takes ~4 hours total. Pretty easy to do. If you come by my place when you hit Utah we can do it here....hell it seems like I have a compressor sitting around even because I replaced mine thinking it needed done but it didn't (that wasn't my problem).
 

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