Intermittent A/C - 2004 Outback Limited

[Riggs]

2004 Outback Limited, purchased used in 2014 w/107,000 miles, currently with 135,000. A/C clutch started to fail in fall of 2015, and eventually froze. Replaced full A/C unit with a Used Unit Spring of 2016...

What's been done: 1) Used a/c compressor unit installed. 2) Full evac of a/c system. 3) Leak test - passed (-25 atm held for 45 mins) 4) Refill with using 2oz red dye, 3oz oil & 17oz R134a.

5) installed New Expansion Valve. 6) Installed New Receiver Drier.

System runs smoothly, clutch engaging, cold air blowing for the first 15-30 minutes, then it goes warm. If I turn a/c off for a few minutes and turn back on, will blow cold again for about 1 minute. This was happening when the outside air temp was in the 60's, below 80's (not sure if it's relevant?). When the outside air temp was 89degrees and the car was up to temp, a/c wouldn't blow, clutch wouldn't engage.

 

I've swapped A/C and Blower relays, same results. A/C clutch gap @.027mm -.03mm. Pulled glove box out a week ago to check cabin air filter...pretty clean. Did not see any blockage nor icing in the area. If the A/C is able to run in the morning for as long as 45 min, there clearly is nothing wrong with it...Is there some kind of a/c temp/thermosensor that I missed? Ready to pull my hair out!!!

Any help would be greatly appreciated - Mel

Edited June 12, 2017 by Riggs

[ferret]

Your Clutch Clearance is TOO MUCH, Should be .0011 to .0015

 

http://www.subaruforester.org/vbulletin/f88/ac-runs-intermittently-04-forester-75562/#post848614

[Riggs]

Your Clutch Clearance is TOO MUCH, Should be .0011 to .0015

 

http://www.subaruforester.org/vbulletin/f88/ac-runs-intermittently-04-forester-75562/#post848614

 Just checked that gap clearance it is .027-.030mm.

2004 Subaru service manual quote

"Compressor

A: INSPECTION

1. MAGNETIC CLUTCH CLEARANCE

Check the clearance of entire circumference

around the drive plate and pulley.

Standard:

0.45 - 0.15 mm (0.0177 - 0.0059 in)

[Riggs]

Your Clutch Clearance is TOO MUCH, Should be .0011 to .0015

 

http://www.subaruforester.org/vbulletin/f88/ac-runs-intermittently-04-forester-75562/#post848614

 Pulled the A/C clutch out this afternoon and removed the only spacer/washer that was in there.  So far so good, but since the ambient air temp has gone down some, i'll have to see if the new clutch clearance will fix this problem once and for all!

[idosubaru]

Sounds like you are but You're absolutely positive it's fully charged and not loosing any pressure at all?

[Silent Bob]

A good test for a flaky clutch is to run the AC until it stops cooling.  At that point, see if the clutch is engaged and the compressor is spinning.  If not,  unplug the clutch connector and see if you have 12v at that point.  If so, the clutch is suspect.  Also check for ground through the clutch itself to make sure the coil isn't open.

 

The quick version of the test is to run AC till it stops cooling then whap the end of the clutch with a hammer or large screwdriver.  If I suddenly starts working again, your clutch clearance is too big.

[GeneralDisorder]

Could be the clutch is not working when hot. Potted coils like the eletromagetic one in the clutch have a tendency to develop shorts when hot. The copper windings expand as the heat up and eventually get wear spots that touch when hot and partially short the coil. This results in it losing the ability to hold the clutch closed.

 

Check amperage draw on the compressor clutch when cold vs. hot. Or check resistance cold vs. hot.

 

GD

[Riggs]

Yes, A/C is fully charged. I was able to run the A/C full blast for up to 45 minutes at a time on early mornings, but the minute I drove it, it would stop, that was the ongoing issue!

 

3-4 days ago, I did remove the spacer/washer in the clutch, and the A/C has not stopped once! Safe to say the issue was the clutch spacing...thanks for everyones help!