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  1. #1
    Join Date
    Jun 2007
    Location
    Upper Alabama
    Posts
    7

    New Goodman heat pump not cooling properly

    I moved into a brand new house recently that has a Goodman heat pump. I'm sorry I don't have the model number with me now, but it is a 3 ton unit, scroll compressor, R22, 1800sf house. It also says it is charged with 188oz of refrigerant, enough for 15' of line. The low/high pressures are listed as 150/300 psi. The unit is running, but the termperature differential between intake and vent is only 12 to 15 degrees. If I set a temperature and leave it alone it can hold that temp, but in the heat of the day it runs almost continuously. I've seen it take two hours to bring the house down 2 degrees in the evening. It didn't heat worth a damn back in March when I moved in either. I've had the installer out to check it and he says the freon level is correct and he can't find a problem. He checked the ductwork to see if there was anything wrong and said it all looked fine. I've called him three times since then and have yet to hear back from him.

    In the mean time I have a 6,000 btu window unit that seems to be doing a better job of cooling the house than the central unit. This just really sounds like low freon to me. The line run looks like it could be 30' and I'm thinking they just hooked everything up and didn't check it out (during the home inspection the unit didn't work - someone had shorted out a wire with a nail. That's now fixed but how could they have checked it out?) I want to check it myself but those pressure readings look awfully high. I don't know anything about heat pumps though - do they seem correct? What else could be causing this? I really want them to fix this because it's under warranty but I'm not sure they know what they are doing.

  2. #2
    Join Date
    Oct 2004
    Posts
    31
    Tell your service person to provide you with his readings. Pressure and temperature. Then come back here and post it. (A good service technicain will always list this information on his service tickets.)

    It's also real handy to have this info available for detemining past operating conditions compared to present.

  3. #3
    Join Date
    Jan 2007
    Posts
    54
    What city are you in, IF by chance you are in Indianapolis I could come by and check for you, There was no info on your profile

  4. #4
    Join Date
    Jan 2006
    Location
    Raleigh, NC
    Posts
    44
    You have not given enough information. Two hours and a two degree drop is sometimes acceptable. Also, it is possible that a 15° difference is not a sign that something is wrong. Low air flow could be the culprit. What you can do is go to the outdoor unit and feel the large refrigerant line to get an ideal of whether it is cold or not. It should be cold to the touch, and will give an indication of cooling or not.

    Tell us outdoor temp, indoor temp, thermostat setting, time of day, etc. To call and pay another HVAC tech may not be a bad ideal. If you are saying that the tech stated that the pressures were 150/300, then that is not good. If you are saying that the unit was not working during the home inspection, then there is no way for it to have been checked out. The home inspector is not the one to check the HVAC system refrigerant pressure. Nor the amp draw. Home inspectors generally do a visual check.

    I would not advise you to check the pressure. You can get frost bite.

  5. #5
    Join Date
    Jun 2007
    Location
    Upper Alabama
    Posts
    7
    Thank you for the offer, but I live in Alabama.

  6. #6
    I can't tell you what's up with your unit but I can tell you this... our 20 year old heat pump (3 ton/1800 sf) is one sick puppy and going to the boneyard next week. Right now, with a good charge in it, the thing will put out 60° at the vent into a 78° house when it's 90° outside. Cycle time is 8 minutes on and 15 minutes off. Pressures are 215/72.

    Tuesday when it was 103°, it was still putting out 63° at the vent when the cycle time was 25 on and 7 off... just before the overload put the compressor on off-duty status for a while.

    Don

    Edit: I also live in Alabama and I'm replacing with a 3 ton Goodman heat pump

  7. #7
    Join Date
    Jun 2007
    Location
    Upper Alabama
    Posts
    7
    I have lived in Mississippi and Alabama all my life and I can't imagine a situation where two degrees in two hours is acceptable. In fact I still have a house in South Mississippi with a 20 year old unit that is on it's last legs and it cools much faster than that. Same square footage, same size unit, more humidity.

    It's possible the filter is really dirty. I plan to pick one up on the way home today and replace it. But if so, wouldn't a dirty air filter restrict the airflow and cause the air to be cooler, not warmer? In fact I may turn the compressor off and let the fan run a while just to make sure it's not freezing up, but there was water dripping out of the drain pipe outside so I don't think that's it. The coils are in the attic so I can't see them.

    The "worst" reading I got was when the temp outside was about 90, the temp inside was 74, thermostat was set to 74, air going into the intake was 72 and air coming out of the vents was 60. Yes, the air going into the intake was cooler than the air around the thermometer - I've checked that several times with the same thermometer - even though the intake is in the ceiling. I can't help but think that's part of the problem though I can't really figure out how.

    The tech did not tell me the readings were 150/300, that's what is written on the side panel on the outside unit. It doesn't give any context to that though (outside temp, inside temp) so I figure it is going by some kind of standard. I haven't seen the actual readings. I'm not sure the tech saw actual pressure readings either - he was using some kind of digital gauge that was showing temperature readings, not pressures. He said it was more accurate but I've never heard of it. Not surprising since it's not my job.

    The home inspector did not check out the A/C, he simply turned it on and it would not work. The HVAC guy came and found the problem and fixed it. Everything seemed fine after that but it was March at the time and nice and cool outside. In fact it was in the 20's at night when I moved in.

    I've worked on A/C's before, both cars and (very limited) home units. I just don't want to work on this one because it's brand new and I have a warranty and I don't think I should have to.

  8. #8
    Join Date
    Apr 2007
    Posts
    6,285
    Quote Originally Posted by ptcooper View Post
    You have not given enough information. Two hours and a two degree drop is sometimes acceptable. Also, it is possible that a 15° difference is not a sign that something is wrong. Low air flow could be the culprit. What you can do is go to the outdoor unit and feel the large refrigerant line to get an ideal of whether it is cold or not. It should be cold to the touch, and will give an indication of cooling or not.

    Tell us outdoor temp, indoor temp, thermostat setting, time of day, etc. To call and pay another HVAC tech may not be a bad ideal. If you are saying that the tech stated that the pressures were 150/300, then that is not good. If you are saying that the unit was not working during the home inspection, then there is no way for it to have been checked out. The home inspector is not the one to check the HVAC system refrigerant pressure. Nor the amp draw. Home inspectors generally do a visual check.

    I would not advise you to check the pressure. You can get frost bite.

    Seems more like it would have to much airflow. On heat pumps in my complex it uses high speed for heating and med speed for cooling maybe it's only on high speed.


    If the line is cold thats a relative term and about completely impossible to back up. You would need to know the exact temps of the line. I suspect that if this poster thinks it's as low as it is. There would be a good chance of it freezing the coil.

  9. #9
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    You said the rating plate showed 150/300. That's not the actual gauge pressures, right? You need PSIG for both high and low, superheat, subcooling and TD across the coil and static pressure would also help. Insufficient information is like asking a doctor what's wrong with you when all he's got to go on is his medical book that says normal humans have a temperature of 98.6.

  10. #10
    Join Date
    Apr 2007
    Posts
    6,285
    Quote Originally Posted by hfkjdsla View Post
    I have lived in Mississippi and Alabama all my life and I can't imagine a situation where two degrees in two hours is acceptable. In fact I still have a house in South Mississippi with a 20 year old unit that is on it's last legs and it cools much faster than that. Same square footage, same size unit, more humidity.
    Relative Humidity is the key to answering this. Not saying that there isn't something wrong with this but a 95ºF with 70% RH and a larger than 25% exchange rate could lend itself to this situation IMO.


    Quote Originally Posted by hfkjdsla View Post
    It's possible the filter is really dirty. I plan to pick one up on the way home today and replace it. But if so, wouldn't a dirty air filter restrict the airflow and cause the air to be cooler, not warmer? In fact I may turn the compressor off and let the fan run a while just to make sure it's not freezing up, but there was water dripping out of the drain pipe outside so I don't think that's it. The coils are in the attic so I can't see them.

    Yes change your filter if you don't know when the last time it was changed. Change it. And yes low air flow leads to higher temp differences.


    Quote Originally Posted by hfkjdsla View Post
    The tech did not tell me the readings were 150/300, that's what is written on the side panel on the outside unit. It doesn't give any context to that though (outside temp, inside temp) so I figure it is going by some kind of standard. I haven't seen the actual readings. I'm not sure the tech saw actual pressure readings either - he was using some kind of digital gauge that was showing temperature readings, not pressures. He said it was more accurate but I've never heard of it. Not surprising since it's not my job.
    That is max test pressures. Pressures vary with load.


    Quote Originally Posted by hfkjdsla View Post
    I've worked on A/C's before, both cars and (very limited) home units. I just don't want to work on this one because it's brand new and I have a warranty and I don't think I should have to.
    As you shouldn't have to although knowing specs about your system will help you in the long run if you have to change companies for any reason.

  11. #11
    Join Date
    Jun 2007
    Location
    Upper Alabama
    Posts
    7
    This is how my old unit is, it is also about 20 years old and needs replacing but it still has a 17 or 18 degree temperature drop, even in 90-95 degree weather. It's working better than my brand new heat pump.

  12. #12
    Join Date
    Jun 2007
    Location
    Upper Alabama
    Posts
    7
    Quote Originally Posted by BigJon3475 View Post
    Relative Humidity is the key to answering this. Not saying that there isn't something wrong with this but a 95ºF with 70% RH and a larger than 25% exchange rate could lend itself to this situation IMO.
    Humidities around here have been very good lately. In fact today it is only 30%. They don't usually get really bad until July or August. I'm going to check temp deltas as soon as I get home. I'll check them before and after I change the filter. I never noted the humidity before but it just hasen't been bad.

  13. #13
    Join Date
    Jun 2007
    Location
    Upper Alabama
    Posts
    7
    No, it's not the actual readings. That's why I was asking about them, they seemed really high. High and low pressures I can probably get. By TD across the coils I assume you mean temperature at the intake and the vent? Done that and can do it again. Do I get the superheat and subcooling temps by just measuring the temps on the high and low pressure lines right by the compressor?

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