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Charge A/C System AGAIN.....I think the compressor may be bad.

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I noticed that my A/C was getting weak again so I checked the pressure. It was down. I added 5 12 oz. cans to get the pressure back up. I had a charge line come loose on me and I lost a good bit before I caught it. I don't think all 5 cans went into the system. With the temp at about 90 degrees outside, I got the low side pressure to about 58 psi and the high side was around 250 psi. I could hear something leaking down at the compressor when I shut the engine down. I think that may be where my leak is. DUH!!! :banghead: I am gonna check the A/C again today and see how it performs. With a fresh charge of R134a, the output temp in the middle A/C outlet was about 60 degrees which is within the specs. that manual calls for. Has anyone replaced an A/C compressor yet? :whistle: Just can't wait to find out what this is gonna cost me. :ahhh:

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Has anyone replaced an A/C compressor yet? :whistle: Just can't wait to find out what this is gonna cost me. :ahhh:

I did a week ago on an F150 where it was a complete PITA to get to. I put new clutch and bearings on it then put it back on. It looks to be 10x easier on a cummins. Just make sure to clean the hell out of where the a/c lines go into the compressor and get it back to torque spec, and not an inch pound less!

I noticed that my A/C was getting weak again so I checked the pressure. It was down. I added 5 12 oz. cans to get the pressure back up.

Five cans may have you way over charged, you can not lower the temp if the pressure is too high, and you are going to slug the hell out of your compressor. Take some of that out. How many ounces does the sticker under the hood call for? You should be running some where between 20 and 30 PSI on the low side. 58 PSI is given you like a 50 degree evaporator temp, way too high. That High side sounds too high as well, it may be causing it to short cycle on the high pressure cut out. http://www.watco.com.mx/HTCPressureTemperatureChart.pdf

I noticed that my A/C was getting weak again so I checked the pressure. It was down. I added 5 12 oz. cans to get the pressure back up. I had a charge line come loose on me and I lost a good bit before I caught it. I don't think all 5 cans went into the system. With the temp at about 90 degrees outside, I got the low side pressure to about 58 psi and the high side was around 250 psi. I could hear something leaking down at the compressor when I shut the engine down. I think that may be where my leak is. DUH!!! :banghead: I am gonna check the A/C again today and see how it performs. With a fresh charge of R134a, the output temp in the middle A/C outlet was about 60 degrees which is within the specs. that manual calls for. Has anyone replaced an A/C compressor yet? :whistle: Just can't wait to find out what this is gonna cost me. :ahhh:

$450 at schucks last I checked. mine seized last year still baking in the cab this year....
  • Author

I went according to the Dodge Service manual on page 24-3. The ambient temp table calls for an output temp in the center panel of 60-70 degrees F. at an ambient temperature of 90 degrees outside temp. Suction (low side) pressure: 50 -60 psi. Discharge (high side) pressure: 215 - 270 psi. When I did the charge, it was 95 degrees ambient temp on the thermometer. So unless the book is wrong, I am well within the parameters of charge pressures. I think I may have let a small bit of air in though. :mad: The system makes a low grumbling sound at first start up, but it cools now. We'll see how long it lasts this time. The reason I used 5 cans is that the charge hose came loose while charging and I did not catch it until the end. I tightened the hell out of the hose connections but apparently not tight enough. :banghead:

  • Owner

I went according to the Dodge Service manual on page 24-3. The ambient temp table calls for an output temp in the center panel of 60-70 degrees F. at an ambient temperature of 90 degrees outside temp.

Suction (low side) pressure: 50 -60 psi.

Discharge (high side) pressure: 215 - 270 psi.

When I did the charge, it was 95 degrees ambient temp on the thermometer. So unless the book is wrong, I am well within the parameters of charge pressures. I think I may have let a small bit of air in though. :mad:The system makes a low grumbling sound at first start up, but it cools now. We'll see how long it lasts this time. The reason I used 5 cans is that the charge hose came loose while charging and I did not catch it until the end. I tightened the hell out of the hose connections but apparently not tight enough. :banghead:

That grumbling noise is too much oil in the system...:rolleyes:

According to Mitchell 1 the total capacity of PAG oil is 6 ozs... Now that being said there is 2 versions of freon out there...

1. Freon 134a.

2. Freon 134a with oil charge.

So now if your system has a slow leak and bled off just the freon (because the oil settle to low points then even can of freon with oil charge will over charge the system with oil...

I too also have a bit of gumble too... (made the same mistake :banghead:)...

Not to see how bad it over charged with oil look at the back of the compressor there a single nipple fitting when the compressor is first fired up and tries to compress the oil it can't so it blows it out the back of the compressor. (Relief valve) I see this on my buddy truck 1992 Dodge... You'll notice a oil dripping off the engine mount...

  • Author

This time I used straight R134a. No oil or anything. I'll put the gauges on it again and double check the pressures. If it seems a little high, I will let some out. Some oil will come out with it.

Pressure is not the most important thing, when I charge systems that are fixed orifice the temp of the suction line is what I go by. Once that contains saturated vapor, it will become cool, and that means the evap is full of liquid refrigerant. You should not have any excess liquid refrigerant returning to the compressor. You best bet, is to take all the freon out, and charge to factory spec. As far as the excess oil goes, now that is another problem. As far as I am concerned they should not even be selling R-134A with oil in it. They compressor calls for a specific quantity, and there is no way to guess the correct amount. Taking the freon out of the high side is the best way to release excess oil.Also over charging tends to fill up the condenser with liquid, guess what, you need the hot gas to release the heat, hence the name condenser, you lose the effective coil area and capacity, condensers should be 2/3 gas and 1/3 liquid. Not to mention excess oil is taking up space in the condenser as well.Guess I am getting carried away with 26 years of refrigeration :smart:

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    • Like 1

    Guess I am getting carried away with 26 years of refrigeration :smart:

    Like hell! Keep going! :cheerleader: Never can learn enough about all this stuff.
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    • Owner

    Pressure is not the most important thing, when I charge systems that are fixed orifice the temp of the suction line is what I go by. Once that contains saturated vapor, it will become cool, and that means the evap is full of liquid refrigerant. You should not have any excess liquid refrigerant returning to the compressor. You best bet, is to take all the freon out, and charge to factory spec. As far as the excess oil goes, now that is another problem. As far as I am concerned they should not even be selling R-134A with oil in it. They compressor calls for a specific quantity, and there is no way to guess the correct amount. Taking the freon out of the high side is the best way to release excess oil. Also over charging tends to fill up the condenser with liquid, guess what, you need the hot gas to release the heat, hence the name condenser, you lose the effective coil area and capacity, condensers should be 2/3 gas and 1/3 liquid. Not to mention excess oil is taking up space in the condenser as well. Guess I am getting carried away with 26 years of refrigeration :smart:

    That's great... Would you mine me put this in the writeup? :shrug:

    That's great... Would you mine me put this in the writeup? :shrug:

    It is all yours Mike, Enjoy :thumb1:
    • Author

    So, if there is too much oil in the system.......what would be the preferred method of purging or removing the oil short of evacuation of the system and starting over? I am thinking draining off some from the high side port. I guess my question would be......would I get the most oil with the system static (shut down) or in full operation? I am thinking that with the A/C system running, I would get the most oil when I purge a little bit off. Is this correct or am I thinking bassackwards? :lol:

    • Owner

    Funny you should mention this I had a long conversation with Pepsi (from over at CF.com) on the phone about this very same problem. He discharge a little bit of freon at a time from the high side while the A/C was running. During this time he kept a IR laser thermometer on the drier and low side pipe watching the temps. During this short little burst of discharge he said that there was huge amount of oil coming out of the high side coating his hand as you see the freon kind of bubble out of it turning to gasous state. Once it got down near 40* he stopped. Now the net result is that he said the grunting noise is nerarly gone when you turn on the A/C for the first time. But the dash temps were about 45*F ... I would personally think of evac the system and then start over from bottom up like Flman suggest then you know exactly how much of each you got oil and freon...

    where can you get a decent set of gauges for a good price. last week i bought the harbor freight and the 2nd use was just checking the dodge. the high side hose's crimp broke @~275psi. the hose's say 500psi on them. wife's uncle(who works on ice machines) told her to get my money back.

    • Author

    I was thinking the oil is not going to come out by evacuating the system is it?

    • Owner

    No... The oil will always settle to thel owest point in the system and stay regardless of the vacuum. So you would have open the system and blow out the evaporator, condenser, and drain the compressor. Might remove the drier can flip it upside down and blow it out... Then put a vacuum on the system and recharger with 6 ozs of oil and then your 3 cans of freon.

    • Author

    where can you get a decent set of gauges for a good price. last week i bought the harbor freight and the 2nd use was just checking the dodge. the high side hose's crimp broke @~275psi. the hose's say 500psi on them. wife's uncle(who works on ice machines) told her to get my money back.

    I'll bet that was fun when the hose crimp let loose! Did you loose a set of draws or did that pants and socks get taken out too? :lol::lmao2::lmao:

    I bought a set of the Harbor Freight cheepees too. I compared them to an old set of Robin Aire, MAC guages I bought when I was working at the John Deere dealership. I couldn't tell the difference in the guages for the most part. The hoses may be a different story. Maybe a better set of hoses would be in order.

    I agree, I would get on the horn to Harbor Freight raising hell about the hose crimp. Make them pony up for a new set or refund.

    ---------- Post added at 04:48 PM ---------- Previous post was at 09:00 AM ----------

    Well, I had about 40 gallons of waste oil to haul to the recyle center and some other junk around the house so I made a 50 mile round trip with the A/C running. It would cool but not real well.

    When I got home I got the gauges out and hooked them up on the truck. The it was 89 degrees and the high side pressure was about 215 with a thermometer reading in the center dash vent of about 62 degrees. I was kinda bummed thinking my leak was much worse than I thought but if figured I would at least try to purge some the excess oil out. The condenser was so so warm.

    With my calibrated fingers, I vented the A/C system is 2.377 2 second bursts by opening the high side valve into the fill hose. To my surprise the A/C high side pressure IMMEDIATELY did the opposite of what I was expecting.......it actually INCREASED. The pressure went gradually from 215 psi to about max of 250 psi. At that point the high side pressure would subtley fluctuate between 240 and 250 psi with the compressor as the compressor cycled on and off. The compressor did not cycle much.

    Upon checking my center dash vent thermometer, I noticed it was now reading a NICE "meatlockerish" 46 degrees. I turned the A/C off for a few minutes to let everything settle and turned it back on and NO grumbling sound. I also noticed that the condenser was not MUCH MUCH warmer....almost hot to the touch.

    I think I may still have a slow leak but at least this should hopefully last me the rest of the summer.

    Thanks for all the tips, comments, and suggestions! :thumbup2:

    Randy, glad it all worked out for you, too much freon and oil is a bad thing, sounds like you got it right this time. :cool:BTW, what is with the cup cake near my screen name? Mike is getting busy again? :hyper:

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