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Thread: Air Conditioning

  1. #1
    Senior Member DonTom's Avatar
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    Air Conditioning

    I know very little about A/C systems. However, I have replaced a few A/C hoses and a condenser before and recharged the systems up and all was fine (for many years after ) in several of my vehicles in the past.

    But now, I have a different problem . . .

    In my 99 Jeep Cherokee, 5.2L, the A/C crapped out today while I was using it. Started to blow warm air, while just before it was cold and I didn't touch a thing when this happened. The car was driven in the 90 degree F for an hour when this happened in a second from cold to hot air blowing.

    So when I got the Jeep home, I check the stuff I know how to check. Voltage at the compressor is okay, and I can hear it engage and disengage as I connect and disconnect the voltage.

    Then I check the pressure at the low port and it is in the RED, almost pinned, way too much pressure, with the A/C set to the max, blowing warm air. Since it's not working at all, I figure I cannot screw anything up, and I have plenty of R134A around, so I released the stuff with a small screwdriver in the low side valve. But this stuff was warm! But it was also green in color. The A/C oil perhaps? Anyway, I drained it all out and refilled it with a large can of R134A w/oil to the proper pressure to see what happens. Still, all A/C pipes are warm, blowing warm air.

    What could be the problem? Did my a/c compressor crap out or something like that?

    How do I test this stuff to see what the problem is?

    -Don- Reno, NV

  2. #2
    Administrator Ken's Avatar
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    Could it be a blocked expansion valve, Don? Mind you, I don't think that would explain the odd color unless an internal seal has blown. To me it does sound like the compressor has failed in some way. You have power, the clutch seems to be engaging, you have fresh oil and refridgerant, I think it has to be something internal to the system.

    Ken.

    This link might help.

    http://www.jeepforum.com/forum/f11/a...83/index2.html
    Last edited by Ken; 06-25-2014 at 04:37 AM. Reason: Link added.
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  3. #3
    Senior Member DonTom's Avatar
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    Thanks for the info!

    But I am not sure where to look for the expansion valve. Never dealt with one before. I searched it on the web and see what it looks like, but I don't recognize it. I also checked some prices. The compressor costs a lot less than I expected, about $200.00 or so. I might just start replacing stuff until it works. The expansion valve is very cheap too.

    -Don- Reno, NV

  4. #4
    Administrator Ken's Avatar
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    Quote Originally Posted by DonTom View Post
    Thanks for the info!

    But I am not sure where to look for the expansion valve. Never dealt with one before. I searched it on the web and see what it looks like, but I don't recognize it. I also checked some prices. The compressor costs a lot less than I expected, about $200.00 or so. I might just start replacing stuff until it works. The expansion valve is very cheap too.

    -Don- Reno, NV
    I must admit, Don, that when it comes to A/C I shrug my shoulders and let my dealer sort it out. Come to think of it, although I will do quite a bit on the 'bike I seem to let the dealer do most things on the car. Modern engines are marvels of engineering but they do nothing for me. Give me an old Ford Capri or a Mini Cooper and I would be in there with my sleeves rolled up.

    Ken.
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  5. #5
    Administrator Ken's Avatar
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    The easy way to find out if your expansion valve is working properly is to put a set of gauges on the system. If the valve has failed or is not working properly you will experience very high pressure on the high side of the system. I can not give you actual numbers because the pressure varies with the amount of refrigerant in the system and the outside temperature. Also the liquid line coming from the condensor going to the expansion block will be extremly hot and the suction line will be warm not cold. Hope this helps

    Found the above but can't find out where valve is although, if your car has one it might well be on the bulkhead (firewall?).

    Ken.

    P.S. If your system uses R134A, I have found a reference to the R134A systems having a 'Fixed Orifice' instead of an 'Expansion valve'. The Fixed orifice looks like a fat part of the line just before it goes into the evaporator coil.
    Last edited by Ken; 06-25-2014 at 03:17 PM. Reason: Extra info.
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    The orifice tube may be clogged with lint, which comes from the desiccant bag in the receiver/dryer disassembling itself, something that happens normally with age.
    You may have to obtain a special puller to remove the orifice tube, usually located at the liquid fitting at the evaporator, as Ken said.
    Sometimes you can get a piece of it with a needle nose vise-grip, but often enough the piece is all you get.
    The orifice tube is just pushed into the fitting, but the o-ring(s) on its outside diameter can hold it pretty tight.
    If you can get it out, just backflush its screen, clean the orifice with a pipe cleaner, etc.
    Oil the o-ring on reassembly.

    Odd colors in the refrigerant could be anti-leak goo and/or fluorescent dye that's added to top-up cans to help in detecting leaks.

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    If you do find lint, it's time to replace the receivar/dryer; you can't just bake it dry again.

  8. #8
    Senior Member DonTom's Avatar
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    I am beginning to think it might be best if I take it to somebody who knows what they are doing. There are several shops that deal with auto A/C in this area.

    If I decide to do such, I will post here what they did to fix it.


    -Don- Reno, NV

  9. #9
    Senior Member DonTom's Avatar
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    Ken,

    Even though I have some older vehicles (96 is the oldest), they all use R134A. R12 was for even older vehicles, at least here in the USA.

    -Don-

  10. #10
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    If you want to DIY, you really should buy an orifice tube puller, a set of gauges, a serious vacuum pump, a gallon of flushing solvent, a pint of compressor oil, a good temperature gauge, and a book to read so you don't hurt yourself. As a DIYer, at least you aren't forced to buy a recycling machine, but it's still a lot of money for stuff you won't need often enough to objectively justify it.

  11. #11
    Senior Member DonTom's Avatar
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    I already have some of the A/C repair stuff but that I have never used . Still new in the box. I have the set of gauges, a vacuum pump (but I don't know how "serious" this stuff is, as it all came from HFT). Perhaps what I need most is the book. Or just drive the thing down to an A/C repair place and give it to somebody who knows what he's doing. I think that is the option that makes the most sense to me.

    I own many vehicles so there is no hurry. I just purchased a new house here in Reno that has been keeping me very busy lately, but we're just about done moving stuff in and such. I am going to keep all three homes (and not rent any). I can use the five garages (3 +2) here in Reno. The new house is on the very top of a hill with a great night view of the Reno casinos as well as the mountains. I will have internet, telephone and installed there today and alarm tomorrow.

    -Don- Reno, NV

  12. #12
    Senior Member DonTom's Avatar
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    I just today got around to taking my 97 Jeep Grand Cherokee Lardo (5.2L) in to have the A/C looked at. My first guess was correct, they replaced the compressor for a little over $700.00. It was 90 F when I picked it up, so I gave it a good test on the way home. It works very well.

    -Don- Reno, NV

  13. #13
    Senior Member DonTom's Avatar
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    Today, I have a new problem with this 97 Jeep (5.2L). Seems I have a coolant leak after I stop the engine. Had the A/C on today as it was hot here today, in the 90's F. But when I stopped, I noticed a fairly bad coolant leak dead center under the very front of the radiator. Too far forward to be the water pump, too center to be a loose hose, so I guess I have a leaky radiator. I cannot see the exact spot because of the A/C thingie in the way.

    But the strange thing is that the coolant recovery tank level is normal. Looks like it leaked out about a gallon of green coolant when I parked and shut off the engine. The temp gauge showed normal (200F).

    -Don- Reno, NV

  14. #14
    Administrator Ken's Avatar
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    Hi, Don.

    If you had the A/C running then the 'liquid' could very probably just be the melting ice that can form round the A/C unit. This has been quite normal on all my cars with A/C. If it is coolant it will have a slightly sweet taste, if it is melting ice it will be tasteless. Also, put some white kitchen paper under the leak and positively check the color is definitely the same as your coolant. If it is condensate it will be colorless. If you had lost as much coolant as your post suggests I would have expected the recovery tank to be empty. To be sure, check the levels again and go for a run without putting the air conditioning on and see if it still occurs

    Ken.
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  15. #15
    Senior Member DonTom's Avatar
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    Quote Originally Posted by Ken View Post
    Hi, Don.

    If you had the A/C running then the 'liquid' could very probably just be the melting ice that can form round the A/C unit. This has been quite normal on all my cars with A/C. If it is coolant it will have a slightly sweet taste, if it is melting ice it will be tasteless. Also, put some white kitchen paper under the leak and positively check the color is definitely the same as your coolant. If it is condensate it will be colorless. If you had lost as much coolant as your post suggests I would have expected the recovery tank to be empty. To be sure, check the levels again and go for a run without putting the air conditioning on and see if it still occurs

    Ken.
    I know about ice melting from the evaporator that forms on A/C units. That would be clear water and usually less than a cup or so. This stuff I am leaking is quite a bit of green stuff. Perhaps pressure too low from leak to fill recovery tank? Or perhaps because it was very hot when I checked the level? Now that it's cool, (I just woke up) I will check it again and see the differences. And will go for another test ride, keeping a better eye on it. But I am pretty sure I have a radiator leak, and a fairly bad one.

    -Don- Reno, NV

  16. #16
    Administrator Ken's Avatar
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    Quote Originally Posted by DonTom View Post
    ............ This stuff I am leaking is quite a bit of green stuff. Perhaps pressure too low from leak to fill recovery tank? Or perhaps because it was very hot when I checked the level? Now that it's cool, (I just woke up) I will check it again and see the differences. And will go for another test ride, keeping a better eye on it. But I am pretty sure I have a radiator leak, and a fairly bad one.



    -Don- Reno, NV
    Fingers crossed that it turns out to be something simple but, from what you say, it does seem like a radiator problem. Thinking about what I said earlier, the recovery tank should, normally, empty somewhat as the engine cools - if there is no vacuum being created, as the coolant loses temperature, then it will stay full so it looks like there was no low pressure being created as the engine cooled down, indicating an air leak. Hopefully it might be a radiator header or pan seam leak - fairly easily fixed, rather than the core. (I guess you automatically checked that the pressure cap was OK.)

    It seems odd though that the temperature, when you stopped, was around normal unless the failure had only just occurred - I have had that happen once when I lost a fan blade which took out the bottom of the rad. The engine dumped all its water and the temp sensor was just picking up conducted heat from the head, initially I saw a tempersature drop then it seemed to return to normal, increasing slowly. I thought I had just lost the fan belt and carried on the last few miles home - I discovered the real extent of the damage the next day. Thanks to my (then) standard mix of Duckhams Q20/50 and STP the engine suffered no damage.

    Keep us posted.

    Ken.
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  17. #17
    Senior Member grouch's Avatar
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    Don't be in a hurry to condemn the radiator. It's possible you have a leak, in which case it will still cool, until the coolant gets too low. The first thing I would check would be the hoses. Granted, the newer plastic/aluminum radiators do tend to lose seams on the tanks. I'd check to make sure you don't just have a bad hose. I replace hoses every 7-10 years. They can look good and be rotten inside.
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  18. #18
    Senior Member DonTom's Avatar
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    I have a guess WRT what happened. I drove the Jeep for about 40 miles today and yesterday, in the heat, with the A/C on, and it did not leak a single drop. Remember, the coolant level was normal AFTER the leak, when checked in the morning with a cold engine.

    I am thinking that perhaps the A/C repair place filled the recovery bottle way too high and it might have leaked out the recovery hose. I tried to follow that hose, and it looks like it could be going to where I saw the leak. It was kinda hard to follow and I didn't put much effort into it, because it no longer leaks a drop and has normal radiator and coolant bottle level and I never added any. But the recovery hose does go in the general direction of where I saw it leak from.

    So my guess is that the coolant was probably low when I brought it into the A/C repair place and they noticed and (over)filled it. Since it was very hot that day and I did a lot of slow driving, it probably way overfilled the recovery tank even more so when I stopped (from the pressure building, with no circulation).

    I cannot think of anything else that can add up.

    So it seems it was nothing. I hope.

    -Don- Reno, NV

  19. #19
    Administrator Ken's Avatar
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    That all adds up to me, Don. Let's hope that all is now well with no more problems.

    Ken.
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  20. #20
    Senior Member DonTom's Avatar
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    Quote Originally Posted by Ken View Post
    That all adds up to me, Don. Let's hope that all is now well with no more problems.

    Ken.
    Well, it leaks again (after I stop the warm engine) and now the coolant level is low, so it looks like I have a real problem that is intermittent. It seems to be leaking on the front side of the radiator where it cannot be seen because of the A/C condenser in the way.

    I guess I will have to change the radiator. AFAIK, it's been in there since new in 1997. But I am almost tempted to try a quick-fix. What are the opinions here on radiator fix in a bottle? I assume won't be good so I should just fix it right.

    I guess this job I will do myself. But I am more and more tempted to pay somebody else to do the job as I get older.

    BTW, is the stock radiator in this 97 Jeep a single row, double or triple? Can I tell by looking at it? Seems all there are available.

    -Don- Reno, NV
    Last edited by DonTom; 08-28-2014 at 03:25 PM.

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