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  1. #1
    Join Date
    Jan 2007
    Location
    Louisiana
    Posts
    68

    Lennox 5 Ton Heat Pump PROBLEMS!!!

    I never claimed to be the best tech. ever but I dont think I am to dumb either. But I have one that is eating me alive. I dont have alot of Lennox experience but I know I dont like them as of now.
    Call started with unit not cooling. Pressures running 200 and 100 ( R-22 ) No sub cooling and 40 degrees Suction SH. Shut Comp. down and no temperature rise on the suction at all. Started comp. again and adjusted on the txv. NO REACTION... Applied real cold temp to bulb and NO REACTION.... I changed the txv but used a kit ( Sporlan). The cage is a 5 ton ( I think that may be an issue on a 5 ton comp.) Started up and it ran the same. Thought then that maybe the comp. was an issue with bleeding pressure releif valve or cracked discharge line internal. Changed the Comp. and still having problems. I do have a little better pressures at 175 and 85 ( 72 Ambient ). 10-14 Suction SH with 10 Subcooling. The suction pressure is still to high. The reversing valve has a 4 degree rise on the suction lines with NO PRESSURE RISE. I was always told there should be no rise at all but 4 degrees dont seem like it would cause this high of suction pressures. 74 degree inlet air and 65 outlet air. 72 degree ambient. Sweat line stops at comp. Rated at 20 amps drawing 14.
    This is a system with 2 TXV's and the one check valve at the cooling txv. Even went as far as to pinch the check valve off thinking it was bleeding through.
    Any questions you have, just ask. I have no pride left, Just need help!!!!!

    Thanks in advance,
    Mike
    The Impossible is possible around here.... It just cost a little more.

  2. #2
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    442
    Quote Originally Posted by Big Mike View Post
    I never claimed to be the best tech. ever but I dont think I am to dumb either. But I have one that is eating me alive. I dont have alot of Lennox experience but I know I dont like them as of now.
    Call started with unit not cooling. Pressures running 200 and 100 ( R-22 ) No sub cooling and 40 degrees Suction SH. Shut Comp. down and no temperature rise on the suction at all. Started comp. again and adjusted on the txv. NO REACTION... Applied real cold temp to bulb and NO REACTION.... I changed the txv but used a kit ( Sporlan). The cage is a 5 ton ( I think that may be an issue on a 5 ton comp.) Started up and it ran the same. Thought then that maybe the comp. was an issue with bleeding pressure releif valve or cracked discharge line internal. Changed the Comp. and still having problems. I do have a little better pressures at 175 and 85 ( 72 Ambient ). 10-14 Suction SH with 10 Subcooling. The suction pressure is still to high. The reversing valve has a 4 degree rise on the suction lines with NO PRESSURE RISE. I was always told there should be no rise at all but 4 degrees dont seem like it would cause this high of suction pressures. 74 degree inlet air and 65 outlet air. 72 degree ambient. Sweat line stops at comp. Rated at 20 amps drawing 14.
    This is a system with 2 TXV's and the one check valve at the cooling txv. Even went as far as to pinch the check valve off thinking it was bleeding through.
    Any questions you have, just ask. I have no pride left, Just need help!!!!!

    Thanks in advance,
    Mike
    Whats the dry bulb and wet bulb in the conditioned space?

    Also double check your charge against the charging chart in the unit.

    One other thing is take the old filter drier you took out when you changed the compressor and cut it open (lengthwise if possible) and make sure there is nothing odd there. If the old filter drier was a inline, do cut it open and make sure all the desicant is still in it.

    All else fails, change the reversing valve might be something internal to the valve that has failed and causing some hot gas to leak by.

  3. #3
    Join Date
    Jul 2007
    Location
    south bay california
    Posts
    132
    if that reversing valve is bleeding through, you could pick up the temp rise, and you would see that suction prsr build up consistenly across both places you measure it.
    A low split is usually consistant with a high fan speed, and can drop suction line temp and prsr by passing less air across a coil.
    heat pumps are a pin in the ass, but with the detailed info you provided, my only two conclusions are too fast of a fan, or a bad reversing valve.
    I wish i had a great way to tell if the rv was fully engaged. I have heard of older systems having wax in the refrig oil, and this was known to build up in places like the metering device and reversing valve causing improper opening and closing.
    good luck

  4. #4
    Join Date
    Jan 2007
    Location
    Louisiana
    Posts
    68
    Thanks Aircooled, I picked up a replacement rv today and will probably replace it tonight. I had 4 degrees rise on my suction line through the valve and seems like any HP class I can remember said there should be NO rise on the valve. I have never been a parts changer but this one has given me a complex. I also picked up a 3 ton cage for that expansion valve and will put it in also. I will let you know what I find.
    The Impossible is possible around here.... It just cost a little more.

  5. #5
    Join Date
    Apr 2001
    Posts
    669
    Sometimes a faulty reversing valve on a heat pump can be difficult to diagnose. I believe this service call will be a valuable experience that will make you a better service tech for the future.

    Jabs

  6. #6
    Join Date
    Jan 2007
    Location
    Louisiana
    Posts
    68
    These are the ones that stick in your throat for a long time. Just dont look like 4 degrees would cause that much pressure rise. Soon as the sun gets off that roof I am going back for more!!! One of those things that eat at ya till you figure it out.

    Thanks
    Mike
    The Impossible is possible around here.... It just cost a little more.

  7. #7
    Join Date
    Jul 2007
    Location
    south bay california
    Posts
    132
    so how did this ever turn out? Any luck with the changes?

  8. #8
    Join Date
    Jan 2007
    Location
    Louisiana
    Posts
    68
    Sorry I didnt let yall know how it went. Rain held me up but I replaced the RV and placed a 3 ton cage in the TXV............. Still the same thing. 165 Head and 100 suction. I did have a little control out of the TXV now that the 3 ton cage was in place. The new RV had a 4 degree rise on it also so I would say that is normal!!! I looked back to the check valve that I called my self pinching off. I had a 90 degree liquid line and at the bottom of the check valve ( checked side ) I had 86 degrees. Same as the other night. I figured as with the RV that was just heat transfering in the copper. A quater inch lower from that temp. measurement was 82 degrees and a little lower than that was 76 degrees all the way down to the suction header to where the temp was the same as leaving the TXV. I figured I had nothing else to lose as I was already in my pocket pretty DEEP!!!!!!! SO I replaced the check valve and now the unit runs fine!!!
    This is one that I know I learned from. I know alot of people would not post this as they would be afraid of being labled a parts changer. I hope this information will stick in your minds like it is burned in mine. Sharing info like this I hope will help us all. The suggestions that some of you mad were greatly appreciated. Having a site like this is helpful as somtimes calling tech support with some of these companies is a joke.

    Thanks Again
    Mike ( the parts changer )
    The Impossible is possible around here.... It just cost a little more.

  9. #9
    Join Date
    Feb 2004
    Posts
    43

    Wink

    sounds like bad vales to me 100# suction, wow . whats the outside air, and return temp. replace the system.....

  10. #10
    Join Date
    Apr 2001
    Posts
    669
    Quote Originally Posted by Big Mike View Post
    This is one that I know I learned from. I know alot of people would not post this as they would be afraid of being labled a parts changer.

    Hey Big Mike,
    ........alot of people would never have the opportunity to run in to this type of problem and gain the valuable exprience. That type of problem is how the really good field service technicinas become really good field service technicinas.



    Jabs

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