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Need help diagnosing Toyota compressor problem

RonJ on Sun September 27, 2015 7:49 PM User is offline

Year: 1998
Make: Toyota
Model: Sienna
Engine Size: 1MZ-FE
Refrigerant Type: R134a
Ambient Temp: ND
Pressure Low: ND
Pressure High: ND
Country of Origin: United States


-1998 5-door Toyota Sienna van with front and rear A/C system

-Original stock A/C system

-Currently A/C system still cools van just fine

-A few times the A/C button light has been noticed to blink, indicating a mismatch between rpms of engine and compressor

-The first most obvious issue is an occasional loud squeaking noise coming from compressor generally at engine start up with A/C on -- noise goes away when A/C is turned off

-Tightening drive belt did not eliminate noise

-Occasionally squeaking noise is heard at engine start up with A/C off -- noise goes away when A/C is turned on

-Specified clutch clearance is 0.02 in, but the gap measured with a dial indicator was extremely small (~0.0005 in)

-Installed new OEM clutch (pressure plate, pulley, coil) from Toyota on the compressor, but surprisingly the very small gap remained the same even after adding or removing shims

-Purchased new Denso compressor with clutch, and it showed the specified clutch clearance of 0.02 in, as expected, though the clutch versions of the new and original compressors are somewhat different. I have not yet installed the new compressor.

-The clutch on my original compressor looks like the one in this picture:
https://www.rockauto.com/catalog/moreinfo.php?pk=2023248&cc=1317543&jnid=472&jpid=2

-The clutch on my new compressor looks like the one in this picture:
https://www.rockauto.com/catalog/moreinfo.php?pk=2561160&cc=1317543&jnid=472&jpid=4


Do my observations suggest the diagnosis that the shaft of my original compressor is damaged, preventing proper movement of the clutch pressure plate on the compressor shaft?

Edited: Sun September 27, 2015 at 8:32 PM by RonJ

mk378 on Sun September 27, 2015 10:00 PM User is offline

The plate does not move on the shaft during operation. Instead there are springs between the two major parts of the plate which bend and allow one part to move toward the pulley while the other part (attached to the shaft) stays in the same axial position.

I think the blinking light detects only situations where the clutch is supposed to be engaged yet the compressor is not turning at the proper rpm. If that happens it turns the clutch off. It couldn't do anything about the clutch sticking engaged.

There's really no such thing as too little clutch gap until it starts to drag when off.

Have you tried a new belt? Also take the belt off and check the bearings in the idler and any other pulleys.

RonJ on Sun September 27, 2015 10:21 PM User is offline

Quote
Originally posted by: mk378
The plate does not move on the shaft during operation. Instead there are springs between the two major parts of the plate which bend and allow one part to move toward the pulley while the other part (attached to the shaft) stays in the same axial position.

I think the blinking light detects only situations where the clutch is supposed to be engaged yet the compressor is not turning at the proper rpm. If that happens it turns the clutch off. It couldn't do anything about the clutch sticking engaged.

There's really no such thing as too little clutch gap until it starts to drag when off.

Have you tried a new belt? Also take the belt off and check the bearings in the idler and any other pulleys.

Glad you responded as I know you from a Civic forum. Thanks for the helpful clarification on how the clutch works.

The belt and idler pulley are brand new. The belt also turns the alternator, which is new too.

In a bench test, I can actually see the pressure plate on the new compressor move toward the pulley when voltage and ground are applied. I did not see any movement in the same bench test of the original compressor. I'm now wondering whether the moving portion of the original clutch is not visible and is internal and only accessible for measuring movement through a slot opening on the face of the pressure plate cover (see picture at link).

However, do you agree that the compressor is likely toast? And if so, do you agree with my current plan to replace the compressor, condenser, expansion valves, O-rings, and receiver/dryer (due to risk of failed compressor throwing metal debris through the system) and to flush out the two evaporators and the hoses and lines? Or is there a way to determine whether or not the compressor has thrown metal debris?

Any recomendations on how to do the flush? I can rent a flush kit and have purchased A/C flush solution. I have a basic, inexpensive air compressor (125 psi) and have constructed about 25-feet of copper pipe leading to particulate filters, coalescing filters, pressure regulator, and desiccant filter to produce dry air for flushing. Thoughts?



Edited: Sun September 27, 2015 at 10:26 PM by RonJ

RonJ on Sat October 03, 2015 4:52 PM User is offline

Quote
Originally posted by: mk378 Have you tried a new belt?

Well mk, it appears that the drive belt was not tight enough. I was eventually led to this conclusion by the fact that I heard the noise a few times at engine start without the A/C on. When I slightly loosened the drive belt, the loudness and frequency of the squeaking increased and, conversely, when I tightened the belt more than I had originally, the noise went away completely. I've tightened numerous drive belts, and never had problems prior to this one. Maybe the dual A/C system requires a tighter belt than I'm used to in order to prevent slippage. It may be time to invest in a drive belt tension gauge, though they look to be rather expensive.

Edited: Sat October 03, 2015 at 4:53 PM by RonJ

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