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  1. #1

    Whistling/Whining Noise From Cold Line Central A/C


    With Summer fast approaching I've turned my A/C on a few times and noticed this piercing whistling/whining noise from my A/C. When I first turn on the unit there is no noise but after about 1.5/2 minutes the noise kicks in. When I switch the A/C off the noise stops immediately. The noise appears to become more apparent the cooler the outside temperature is. The noise happens at both the condenser and evaporator side. I asked this question elsewhere and was told to block the condenser fan for five minutes to see if the noise changed. I have done this twice so far and each time after a few minutes the noise goes away just about completely. As you would imagine after unblocking the condenser the noise comes back after a few minutes. I was told this means the low refrigerant. If that is the case would that also mean I have a leak? If that's also the case would would be the next step? Have a tech refill and run some leak stopper product? The unit (Heil) looks ancient and if I were to guess I would say it's from the 80's. I can't find the model or anything on Google. Thanks for the help.

  2. #2
    Update: Today we hit a max temp of 90F outside and the A/C couldn't get the temp in the house down past 78F. Does this coincide with low refrigerant as well? I thought the lines/evaporator freeze too under low levels or is that not the case if the level isn't super low? The pump for the water has been going so I don't think the evap is frozen. Thanks.

  3. #3
    Join Date
    Aug 2003
    Fort Worth, TX
    DO NOT allow the leak stop product to be used, even if your equipment is older than the universe. The service tech who ultimately will need to remove refrigerant from your system when it dies will hate every last drop of that leak stop as it fouls his recovery machine.

    You probably have a leak, and it may be in the evaporator. Current R22 refrigerant prices do not make "gas and go" a cheap alternative to fixing leaks anymore, but a leaking evaporator is a losing proposition to leak fix when it is old. You may have to bite the bullet for new equipment.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.

    A building is NOT beautiful unless it is also comfortable.

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