Engine Size: 4.0
I had a holed high side hose last year and took the opportunity to flush and R&R my whole system. I re-used the old FS10 compressor since there was nothing wrong with it. Everything was fine, blew nice and cold until the other day I was on the highway (100+ degree day) and the clutch let go. No noise, just suddenly burning smell in the cabin and no cold air. The plastic clutch plate had melted and fell apart.
The clutch pulley and compressor shaft both spin cleanly. Was it just the clutch slipping, overheated? I would like to think so, except:
1. There was oil on the bottom of the compressor body where the case comes together and puddled in the engine bracket underneath
2. No oil drained from the compressor when I spun the shaft
3. If I put my finger over the high side port and turn the shaft several turns, there appears to be no compression.
What do those with more experience with the FS10 surmise happened here? Hate to flush it all out again and redo from scratch but I also really don't want to waste my new compressor...
Good bet you will need to flush the system again.
Though not as bad as the FX-15, the FS-10 is basically a throw away unit. FS-6 was better. Even if only the clutch were bad, I wouldn't throw good money after bad on this thing.
Is it the original compressor? If so, after 20 years I think you got your money's worth.
Okay okay, you all twisted my arm. I don't think it was the original compressor since it was marked for use with R-134a, but it definitely looked old enough.
The system has a low side accumulator and a variable orifice valve installed as well as new non-muffler compressor hoses.
Can I remove the accumulator and back-flush the whole thing into the evaporator low side fitting all the way through and out the compressor discharge fitting, leaving the orifice tube in place, and then just replace the accumulator, or do I really need to take everything apart again and flush each component piecewise?
Edited: Fri June 24, 2011 at 4:11 PM by runderwo
Read Hecat's tech page on flushing.
Well, sad to say I don't have the complex equipment they recommend, just a compressed air flush canister, but the answer to my question seems to be no, you can't flush through the orifice tube, so it'll have to come out. Oh well.
Nope. Each component separately.
But on those vehicles. It's pretty much a firewall forward replacement. Flush the evap is about the best you can do.
Unless you got really lucky, usually a clutch blows apart because the compressor blows apart internally, and by that time the whole system is completely contaminated. Look at the components... compressor manifold, OT, inlet and outlet of condenser... if there's gunk anywhere in the system, as Tim noted, it'll probably be a full firewall forward replacement.
If your condenser is a tube and fin, you might have some luck with flushing, though still it's better off to replace because the stuff typically just bakes on and typically doesn't get dislodged during the flush. But once the system is charged up and running, then the gunk gets dislodged, resulting in repeat contamination. A parallel flow or serpentine condenser has to be pitched. Maybe you can get a few bucks from the scrap aluminum.
Haven't seen any gunk anywhere yet, just clean aluminum in the compressor outlets and the manifold hose end, but with what appears to be a compressor that leaked the system oil out of its case and totally burned out. I will do a post mortem on the compressor and see if that lends any knowledge as to what happened. Can I assume if the orifice tube (1 yr old) is not full of debris that the condenser and hoses will be okay after a routine flush?
Edited: Sun June 26, 2011 at 11:32 PM by runderwo
No, you can't assume, you need to pull the OT and that will tell much of the story. If the OT has stuff on it after one year, that stuff got into the condenser too. You might also want to consider the addition of a filter, post repair.
No place to take shortcuts with a new compressor, you absolutely have to make sure the system is squeaky clean, or risk repeat failure.
If the system was converted to R-134a, you might want to upgrade the condenser anyway while you're at it.
Took it apart today and the orifice tube had some black junk on it, but nothing dark came out of any other component except the evaporator, which in my experience is normal for some brown stuff to come out at first. The condenser is OEM tube and fin type, I back flushed it and let it sit then flushed it again, nothing interesting came out. Unfortunately, after adding oil and dye and reassembling it wouldn't vacuum down. After pressurizing with inert gas I found a crimp leak on the compressor discharge hose. Motorcraft hose just over 1 year old, a little unbelievable. Going to get that crimp fixed at a shop this week. I wonder if this leak contributed to the burnout in some way?
Edited: Sat July 02, 2011 at 6:14 PM by runderwo
I took apart the old compressor and there wasn't any discernible scuffing on the bearing surface nor was there any apparent trouble with the piston rings.
Two of the five cylinder walls, however, had significant vertical scuff marks. I am tempted to say that what happened is that the compressor case seal blew out, throwing oil and refrigerant out the high side and the compressor temporarily seized, scuffing those two cylinders and wrecking the still-engaged clutch, before the low side freon would have dropped low enough to cycle the clutch (there is no high side pressure switch). Not sure how the high side crimp leak would have played into it, or how there was still 100 pounds of static pressure left when I got it home. Just a mystery.
Edited: Mon July 04, 2011 at 11:55 AM by runderwo
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