letsbangout
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- Dec 3, 2010
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This is a LONG story, bear with me please. When I bought my truck with 70k original miles, I was told that the AC system had a leak. Little did I know the low-side cuton switch was also bypassed; how dumb. So one night I tried turning on the AC at highway speeds.. the drive belt broke immediately. (FYI, I had no problem driving another 20 miles with no belt; no overheating issues at highway speeds, no excessive battery drain w/ headlights on, etc. It had enough juice that I could drive it another mile to the parts store to fix it the next day).
So the compressor was immediately bad. It might've been leaking before, or been on the way out, but it was definitely gone at this point. So I bought a new Delco compressor, new Orifice Tube, new Accumulator, new set of Manifold hoses, and a new set of condenser tubes (the ones that run from the front and rear evaporators into a Y-pipe and into the condenser), and a new expansion valve for the rear evaporator. It's my understanding that the expansion valve can get clogged if there is any crap passing through it, which is a reasonable expectation when you have catastrophic compressor failure, so I bought a new one sight-unseen. Also you'd have to get into the back to disconnect the expansion valve in order to flush the system anyway, so might as well start from scratch.
I bought 4 cans of 12oz. charge at Advance Auto parts (my calculations tell me I needed exactly 3.66 of those cans for a full charge), and 8 oz of PAG-150 in the bottle. Yesterday I took my truck to a guy who had an extremely reasonable labor rate and had gauges and a vacuum pump, along with all the tools in a hole-in-the-wall shop. That might've been a mistake. I did a lot of reading beforehand of TSBs in Alldata, as well as documents from Delco like this one: http://www.acdelcotechconnect.com/pdf/pi/oil_balance_card.pdf - it called for pouring oil into the accumulator and into the compressor. We did that, but maybe half an ounce into each, because the guy had no measuring cup by which to drain and measure the oil in each component. Of course I didn't know that until we were already into it. He had an oil fill attachment on his gauges (goes in-line with the "new refrigerant can tap" so that refrigerant will push the oil into the low side while charging the system).
Here's my problem: the low and high side gauges never got high enough for my liking. I read in the Haynes AC book that it should read 35 and 238. The readings in 78 degree ambient temps were 25 and 200. Thinking back, perhaps the issue was that the compressor already had oil, and we added the full 8oz can on top of that. So the system could be full of oil and thus can't fully cool, even though it's got the right amount of refrigerant, I think.
So tonight, given that I don't own a set of gauges (going to order a Robinaire gauge and hose set very soon!), I bought one of those Interdynamics "charge cans" with a low-side gauge tonight. I hooked up the gauge only, it read 45 on the low side in 78 degree weather. That's a little high. I figured there was either a blockage somewhere, or a bunch of left-over flush in the system (we only vacuumed it for about 25 minutes, and I really wanted to vacuum it more, as I could still see the mist of the Medium Reducer flushing solution coming out of the vacuum pump even after 25 minutes). So I squeezed off some of the low-side gas onto my finger. For the first 2 seconds, it was gaseous, then it started spraying oil more fervently. I let it spray out for a good 5 or 6 seconds onto my finger to check for the presence of contaminants - I saw none, it was clean as a whistle. But I began to notice just how oily the discharge was. I did it again - for the first 2 seconds it was gaseous, and after that it became gaseous and very oily. I blew some out onto my fan shroud to get a good look at it, and it's slightly green. See the picture attached.
One other thing I should say is that the reason for all of this is that it still doesn't cool as much as I think it should. I'm guessing the air is maybe 60 degrees (haven't measured, it's not cold enough to justify that). It should be absolutely freezing right now! In 80 degree weather, at night with no sun, it should be producing 40 degree air inside the vent. So what's the diagnosis; does anyone think as I do that there might be 9 or 10 ounces of oil in the system? And what should I do, suck some of the oily refrigerant out and recharge with new refrigerant? And if that's the case, how do I know when I've gotten out the right amount of oil? Or maybe I'm completely off-base?
Thanks in advance!
So the compressor was immediately bad. It might've been leaking before, or been on the way out, but it was definitely gone at this point. So I bought a new Delco compressor, new Orifice Tube, new Accumulator, new set of Manifold hoses, and a new set of condenser tubes (the ones that run from the front and rear evaporators into a Y-pipe and into the condenser), and a new expansion valve for the rear evaporator. It's my understanding that the expansion valve can get clogged if there is any crap passing through it, which is a reasonable expectation when you have catastrophic compressor failure, so I bought a new one sight-unseen. Also you'd have to get into the back to disconnect the expansion valve in order to flush the system anyway, so might as well start from scratch.
I bought 4 cans of 12oz. charge at Advance Auto parts (my calculations tell me I needed exactly 3.66 of those cans for a full charge), and 8 oz of PAG-150 in the bottle. Yesterday I took my truck to a guy who had an extremely reasonable labor rate and had gauges and a vacuum pump, along with all the tools in a hole-in-the-wall shop. That might've been a mistake. I did a lot of reading beforehand of TSBs in Alldata, as well as documents from Delco like this one: http://www.acdelcotechconnect.com/pdf/pi/oil_balance_card.pdf - it called for pouring oil into the accumulator and into the compressor. We did that, but maybe half an ounce into each, because the guy had no measuring cup by which to drain and measure the oil in each component. Of course I didn't know that until we were already into it. He had an oil fill attachment on his gauges (goes in-line with the "new refrigerant can tap" so that refrigerant will push the oil into the low side while charging the system).
Here's my problem: the low and high side gauges never got high enough for my liking. I read in the Haynes AC book that it should read 35 and 238. The readings in 78 degree ambient temps were 25 and 200. Thinking back, perhaps the issue was that the compressor already had oil, and we added the full 8oz can on top of that. So the system could be full of oil and thus can't fully cool, even though it's got the right amount of refrigerant, I think.
So tonight, given that I don't own a set of gauges (going to order a Robinaire gauge and hose set very soon!), I bought one of those Interdynamics "charge cans" with a low-side gauge tonight. I hooked up the gauge only, it read 45 on the low side in 78 degree weather. That's a little high. I figured there was either a blockage somewhere, or a bunch of left-over flush in the system (we only vacuumed it for about 25 minutes, and I really wanted to vacuum it more, as I could still see the mist of the Medium Reducer flushing solution coming out of the vacuum pump even after 25 minutes). So I squeezed off some of the low-side gas onto my finger. For the first 2 seconds, it was gaseous, then it started spraying oil more fervently. I let it spray out for a good 5 or 6 seconds onto my finger to check for the presence of contaminants - I saw none, it was clean as a whistle. But I began to notice just how oily the discharge was. I did it again - for the first 2 seconds it was gaseous, and after that it became gaseous and very oily. I blew some out onto my fan shroud to get a good look at it, and it's slightly green. See the picture attached.
One other thing I should say is that the reason for all of this is that it still doesn't cool as much as I think it should. I'm guessing the air is maybe 60 degrees (haven't measured, it's not cold enough to justify that). It should be absolutely freezing right now! In 80 degree weather, at night with no sun, it should be producing 40 degree air inside the vent. So what's the diagnosis; does anyone think as I do that there might be 9 or 10 ounces of oil in the system? And what should I do, suck some of the oily refrigerant out and recharge with new refrigerant? And if that's the case, how do I know when I've gotten out the right amount of oil? Or maybe I'm completely off-base?
Thanks in advance!
