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AC Compressor Noise when engaged (video) - Is my compressor going out?

('06-'08) 
7K views 6 replies 3 participants last post by  klevin99 
#1 · (Edited)
Just bought this 08 Sports XT last week. AC isn't blowing cold and compressor initially didn't turn on. Added r134a, and now it does, but with a weird ratcheting/scratching sort of noise. My brother said it sounded like the buzzing from high-voltage power lines. It only happens when the compressor kicks in. I know the compressors do make a noise like this when they're on but all the ones I've heard are MUCH quieter. According to the previous owner, "the AC was blowing cold in August. [he] hasn't used it in a while". I'm guessing the compressor was sitting motionless without oil for so long that the internal piston may be going bad. Do I need a new compressor? Should I run it like this for an extended period of time?
Also, the belt is fraying, but I've already bought a replacement.



More detailed info:
Hey all, just bought an 08 Sports XT last week. Went to go use the AC a few days ago and noticed the compressor didn't turn on when I pushed the button. Called my mechanic, he said the system could be empty and to buy a recharge bottle. I bought a bottle and started to fill it up, sure enough when pressure was added to the system again it kicked back in, albeit with a weird ratcheting, scratching sound. I filled it up to the recommended pressure but noticed it wasn't blowing that cold. Tired, I called it quits for the night.
The next morning I went outside to test it. Turned the AC on and the compressor didn't turn on... hmm. I connected the bottle and noticed the pressure was low. Added a tiny bit more r134a and the compressor kicked back in. When I was filling I noticed that every time the needle would land on the recommended pressure and then fall off when I released the fill lever. There must be a leak somewhere.
 
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#2 ·
get to an AC shop. They should have leak testing equipment you can't afford. Leak could be compressor, condenser, hoses, hose connectors and so forth. Solve that problem first unless they say the compressor is toast from the get-go.

The reason it would not turn on is that there's a pressure switch in the coolant circuit that shuts off juice to the clutch when the pressure is low.

Keep in mind too that the compressor needs lube. Recharging protocols discuss adding oil, either premix or separately, as well as coolant. The oil essentially dissolves in the coolant, so leaks can bleed lubricant out too. That could be the reason for your noise.
 
#3 ·
That equipment is more affordable than you think :D but also requires a license. Regardless... it was at the shop when you posted yesterday, and they told me I need a new compressor. The compressor leaked and basically hasn't been turned on in 6 months. The recharging bottles also have oil in them but it can only do so much when the internals have sat unused for so long.
 
#4 ·
I'm absolutely amazed your mechanic recommended you adding an over the counter can, those things are the devil. The primary issue is as you noted they add oil in addition to coolant. Not to forget the other various additives that are commonly found that play havoc with other parts of the system "leak sealers", etc. There are many cases where the system oil level is just fine, there is no golden ratio of pre-mix to add - its all dependent on the location and type of leak. In many cases with leaks, all that needs to be replaced is the coolant itself (which is available without oil). The issue is, when you start adding too much oil, you displace coolant and it turns into a vicious cycle.

The proper procedure would have been to add a dye to the system and top off with straight coolant and then used a UV light to diagnose and repair the leak after evacuation. Or ideally just top the system off until the compressor activates, and then use a leak sniffer (they're actually pretty cheap and require no license).

Well, at least you're fixed - although I would seriously question the route used to get there....
 
#5 ·
My mechanic actually told me AC is the one area he doesn't have a lot of experience in, and he also doesn't have a license for it which is why I took it to another shop for an actual diagnosis. However, before I took it to a different shop he told me the reasons the compressor didn't kick on in the first place and that the main reason is that the system could be completely empty. So I went with that and bought a bottle.
Turns out it leaking from the fitting that attaches directly to the compressor, as well as the fitting near the radiator.

So I guess my next question is, when I replace the compressor and O-rings, what should I use to fill the system up?
 
#6 ·
Since you had a bad compressor, it's a little bit more involved then just slapping a new one on there, especially if you want to get a good life out of the new one (and be reliable).

Steps to take:
Remove old compressor, old TXV, and old dryer - get replacements for all of these.
Flush the lines using a flushing kit (pretty cheap).
Install new compressor, TXV and dryer.
Reference the FSM for proper amount of PAG (oil) to add for a complete fill since you're flushing the system.
Service the oil, draw a vacuum for a minimum of an hour or so to ensure no leaks remain, then have the system serviced with the FSM specified weight of R134 for a complete fill (it is available without added oil).

Or do the replacement and flushing yourself and have a shop do the servicing...
 
#7 ·
If you want a compressor that will last a while, and a system that will work, even in hot weather, have a pro do it, at least the charging. As others have said, you need special equipment like a vacuum pump, and probably better guages than you're willing to buy. Not to mention the risk of working on a high pressure system when you don't know exactly what you're doing.

Do it yourself charging is not worth the risk, IMHO.
 
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