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  1. #1
    Join Date
    Jul 2008
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    Question How long for refrigerant to cool down?

    I'm a noob to this forum, so go easy on me.


    I have a Comfortmaker 2-ton unit for my upstairs. The compressor went out yesterday and I had it replaced today.

    My question is this: once the unit is recharged with refrigerant, how long should it take for the unit to cool the refrigerant down and start cooling the house down any appreciable amount?

    Thanks for your help!

    Matt

  2. #2
    Join Date
    Mar 2006
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    254
    Wasn't the tech there to make sure all things checked out normal?

    If he did, it depends on what ambient inside temp there is when starting AC.

    Your return duct is returning inside hot air as well as everything inside your house
    being "hot" right now.

  3. #3
    Join Date
    Jul 2008
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    Yes, he was there, and everything checked out ok after he installed it and recharged the system. I just wanted to know how long it should reasonably take for the refrigerant line to get cold when recharged with warm refrigerant. The refrigerant has to get cold prior to cooling the house down, correct?

  4. #4
    Join Date
    Mar 2006
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    254
    You should start feeling cool air pretty quickly now. Are you concerned you are not feeling cool air after 5-7 minutes? Everything is heated up after for the time being, ductwork, drywall, sticks of furniture...everything. Give it some time.

  5. #5
    Join Date
    Jul 2008
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    No, I'm concerned that the refrigerant line from the outside unit to the air handler in the attic is not getting very cold yet.

    Prior to the compressor failure, the refrigerant line would be very cold to the touch and have a lot of condensation on it. It has been on for approximately 2 hours since the tech left, and it's still only cool to the touch at this point.

    I realize the air in the house will take some time as it heated up all day, but the refrigerant should be getting cool by now, right?

  6. #6
    Join Date
    Dec 2007
    Location
    Ohio
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    2,876
    Quote Originally Posted by chewreck View Post
    No, I'm concerned that the refrigerant line from the outside unit to the air handler in the attic is not getting very cold yet.

    Prior to the compressor failure, the refrigerant line would be very cold to the touch and have a lot of condensation on it. It has been on for approximately 2 hours since the tech left, and it's still only cool to the touch at this point.

    I realize the air in the house will take some time as it heated up all day, but the refrigerant should be getting cool by now, right?
    Forget about that line and tell me how cold the air is coming out of your registers. How long has the unit been running....how much has the temperature dropped since then??
    I need a new signature.....

  7. #7
    Join Date
    Jul 2008
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    Quote Originally Posted by I_bend_metal View Post
    Forget about that line and tell me how cold the air is coming out of your registers. How long has the unit been running....how much has the temperature dropped since then??
    The unit has been running for approximately 2.5 hours now, and it has dropped the inside air temperature 2 degrees. I don't have a thermometer to measure the register temperature.

  8. #8
    Join Date
    Dec 2007
    Location
    Ohio
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    2,876
    What is the temperature outside approximately? What does your thermostat say the indoor temperature is?
    I need a new signature.....

  9. #9
    Join Date
    Dec 2007
    Location
    Ohio
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    ....and what part of the country are you in?
    I need a new signature.....

  10. #10
    Join Date
    Jul 2008
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    8
    Quote Originally Posted by I_bend_metal View Post
    ....and what part of the country are you in?
    I'm in Greenville, SC. The outside temperature is approximately 87 degrees (has been over 90 all day).

    The indoor temperature was 80 when he turned on the recharged unit around 6pm tonight. It's now 8:41pm and it is 78 degrees.

  11. #11
    Join Date
    Mar 2006
    Posts
    254
    88 is trying to make the same point I did.

    It's perfectly normal for a house that's heated up (drywall, ducts and all) to get the temp down...even 2 degrees over 2 hours!

    Tomorrow, if you are still in doubt, drop by your local Radio Shack and buy one of those cheap indoor/outdoor digital thermometers (like I have) and use the probe to check the temp coming out of your register. After an hour of two, it should be 17-20 degrees below that particular rooms ambient temperature.

    That's all I can suggest. Go from there.
    Even my small condo takes awhile for my AC to cool down my condo. The AC is busy trying to cool down everything that has heated up. That means everything from the drywall to your pots and pans.

  12. #12
    Join Date
    Dec 2007
    Location
    Ohio
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    2,876
    Actually with those temperatures, that line should be sweating. You have a large load of heat you are trying to remove from that house. While Caslon is right about it taking some time to do this....you should be falling a little faster than you are. I would have that installer back ASAP and have him set up the unit properly. Sounds to me like he has it undercharged.

    Do you know if he used nitrogen to pressure check that system after the compressor install? Did he use a micron gauge when he pulled his vacuum? Did he check super heat and sub cool when properly charging the unit?
    I need a new signature.....

  13. #13
    Join Date
    Jul 2008
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    8
    Quote Originally Posted by I_bend_metal View Post
    Actually with those temperatures, that line should be sweating. You have a large load of heat you are trying to remove from that house. While Caslon is right about it taking some time to do this....you should be falling a little faster than you are. I would have that installer back ASAP and have him set up the unit properly. Sounds to me like he has it undercharged.

    Do you know if he used nitrogen to pressure check that system after the compressor install? Did he use a micron gauge when he pulled his vacuum? Did he check super heat and sub cool when properly charging the unit?
    I know that he used nitrogen and did a pressure check at 150 psi and then charged the refrigerant. I would've thought the line would be sweating at this point as well, and that was the point of my original question. I realize the house is hot and will take time to cool down, but I thought the refrigerant line would be sweating by now.

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