Engine Size: 1.6L I4
Refrigerant Type: DuPont 134a
Oil: PAG46 (4.6oz)
Expansion valve: new
Problem: Belt squeal when the clutch engages
This is the third install I've done in 3 years on this car so this post will be rather long. All four installs have done this very same thing. When I first start the car and engage the compressor, the belt will squeal for about 6-8 seconds. It also hits the engine idle very hard. If I feather the throttle, I can get it to not die and eventually the squealing will stop. After this it's fine (usually). If it squeals again, it's only after I drive off and even then it's only for a few seconds. The rest of the time it's quiet and cools fine. I have already been down the belt road. Tightening, tightening some more, loosening, loosening some more, new belt, etc. It's something I'm doing as part of the install that's screwing it up. With this last compressor, I started the ac for the first time *while driving down the highway* and it snapped the shaft off and damaged the seal. I received some bad information the first three times so I figured this time I had it licked. I just charged the new install, and after driving it for about 20 minutes, the belt squealed for about 1 second on engagement. Here we go again!! Here is my prep and install procedure. What am I doing wrong?
1. Remove all the components and tape to prevent any (more?) contamination.
2. Flush each line and evap by pouring flush down it and blowing it out with a air nozzle with a rubber tip. This time I used one full quart of flush on the evaporator. One full quart on all the lines. Everything else gets replaced(compressor, dryer, condenser, expansion valve). I re-tape all the ends after flushing.
3. Un-tape, clean the ends, and install new o-ring and assemble in place starting with the evap and working back to the compressor. Rings are lubed with silicone oil. I skip the dryer and do it very last. Usually 10 minutes between hookup and vacuum.
4. My system takes 4.6oz full charge. I put 2.5oz directly in the suction port of the compressor. Turn in CCW (according to engine rotation) a few times, recap, and turn pulley down for about 10 minutes. I use a new horse syringe to measure out the oil.
5. Install compressor, hookup the lines, and turn the compressor CCW by hand for several minutes.
6. Install 1.1oz of oil in dryer.
7. Install 1oz of oil down the low side port. The line is vertical, so it runs down away from the compressor. There is about 4' of line before it hits the compressor.
8. Pull vacuum. I have an old school oiled Gast Mfg. single stage that is smooth as butter and pull 29". Vacuum for 8 hours. (3 last night, 5 this morning).
9. I don't entirely trust my gauges, so I usually pull 29" and disconnect them, wait 30 min, and reconnect. There is 15"-ish vacuum left in the system.
10. Flush my manifold, and hoses with flush, then vacuum for 45 minutes to remove any residue.
11. Hook up my refrigerant and weigh in 21.2oz (the low side of the window) using refrigerant scales. It usually takes about 45 minutes. The only thing I do to speed it up is warm the can with a hair dryer.
12. Cap and drive gently, not revving up the engine over 3K.
The first time I replaced the system, the compressor shop told me to add 6oz of PAG100 directly to the compressor. All of it! 10 minutes into the charge it was pushing oil out of the bolts on the back of the compressor. I took it back. $60 in oil, refrigerant, and flush later, it was doing it again. I took it back again and this time I went to an ac tech for the measurements (4.6oz spread out). With new measurements the system held for two years, but it's always squealed. I also found out the oil viscosity, is 46, not 100. (Lesson: Don't ask the compressor guy system questions. He just builds them.) Since *then*, I found out that, apparently, the viscosities are so close, it really doesn't matter. And now it appears that it's going to start doing it again! AAAAAAAAAARRRRRRRRRRRRRRRGHHHHHHHHHHHH!
The squealing sounds like some type of liquid lock. Almost like there is a slug of oil that accumulates in the compressor when it sits. It has to move that oil before it can compress properly. I have no idea. I'm at my wits end at this point. I'm beginning to think there is no way to charge a small system like this without one of those $20K machines that charges the oil and refrigerant at the same time.
Any information or criticism?
Wow. When you mentioned 3 compressor installs, I figured it was a failure to flush situation causing the problem, but then you describe a flush and replacement of the condenser as well, so it wouldn't appear to be an issue of cleanliness.
I would take serious issue about charging into a mere 15" vacuum. If you don't trust your gauges, then fix them or get new gauges. Bottom line is 15" is WAY too little vacuum. I'm skeptical that it's the root cause of your compressor squeal issue however.
It certainly sounds like a compressor lubrication problem. Since you pre-charge the compressor with oil, it doesn't make sense to have ANY squealing on initial startup. Besides your gauges, what's been the same between all these installs? Compressor brand? Compressor clutch (being transferred from old to new)? I'm not familiar with your particular compressor, but is it even possible that there are additional ports that require lubrication on the compressor?
Only other thing - you didn't post any low/high side pressures of the system in operation or mention anything about the cooling performance.
Thanks for the response!
Sorry, I was unclear; I charge into 29". I just use the disconnect/connect to make sure it will hold a vacuum. I pull another 30-45 minutes at 29" right before charging.
On initial charging startup, the compressor clicks on nice and quiet. No problems. It's the next day(and every other day after that) that the squealing starts on initial engagement. I haven't run it again since the install yesterday, but if it squealed one hour into the breakin, I bet it starts up again this evening.
Unfortunately, the only continuum in the installs is me. :-) That's why I wanted to post my process; I'm introducing something into the mix and it's breaking things. The first two compressors were rebuilt units. I purchased the condensers, driers, and valves from him as well. The third compressor was a brand new Sanden from the same guy but I got the condenser, drier, and valve from an auto parts store. This new compressor I installed yesterday I got from a new distributor. It's new, but it isn't Sanden. All the parts are Murray from an auto store. Perhaps the only other continuum would be that I use DuPont Suva refrigerant. But that isn't the issue.
Additional information. Last night I disassembled the old compressor and found that the inner 180deg of the rotating scroll had separated from the base. The static scroll had a crack in it from all the frag. The interior of the compressor is spotless clean; no black powder and the bearings are spinning nice and smooth. The only particulate in the compressor is shards of material that can be picked out with tweezers. It seems to indicate that there was already oil pooling in the compressor or the valve is failing and allowing liquid back into the compressor chamber? Not sure how liquid would be present immediately in a system that has been resting for 8 hours. The pressure relief is still intact.
I will have to purchase new hoses and post the pressures. The gauges are fine, it's just that the hoses are about 4 years old and I don't trust the seals any more. I'm getting paranoid. :-)
I'm afraid the gauges won't show anything since the compressor isn't really turning when it squeals. Once it spins up it seems to work fine. It cycles about 30s on and 8-10s off with the engine at 2500rpm.
So, as predicted, it's squealing again.
I put the gauges on it and ran it with the following results.
The 400 was the peak running it at about 2000 rpm. It usually hovered around 380. The closer it got to 400 I could hear the belt starting to slip and squeak. The high side is too high if you follow the 180 + ambient formula. Expansion valve? That's a lot of new valves doing exactly the same thing. Overcharging could be suspect, but I only put in 21.2oz out of two 12oz cans and there is a little left in the second can. The max it can take is 23oz so 24oz minus a few tenths to purge the line with each can and it couldn't be much more than .5-.6 oz over if my scales were inaccurate.
Yeah, that high side pressure is sky high....WAY too high. I'd definitely spray the condenser with water to see if the high side drops like a rock to see if there's a heat transfer or cooling fan issue, but it's unlikely that's issue as you've replaced the condenser several times it sounds like. I don't suppose the TXV is installed backwards is it (in the rare case that it's actually possible to do so)? If it was, I'd think the low side would go into vacuum coupled with the sky high high side pressures.
Finally, are you absolutely certain the evaporator is clear? Did you remove the evaporator to flush it? If you just poured in the flush and blew it out briefly with an air gun, that's nowhere near enough to do much good, especially if it remained in the vehicle while doing so. It sounds like that's one item that has remained a constant in all the work you've done thus far as well.
Edited: Tue July 01, 2014 at 2:43 PM by webbch
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