Question about Heating & Cooling

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Check cooling coil(in door unit)if there ice buil up then feel air vent if no air mean your fin block aready need to clean / air vent ok meant there have a leak .you need r22 test gauge and hose,reamer,tube cutter and flaring kit. 1)check suction pressure(big tube at out door unit) remove 2 way cap and 3 way cap valve then connect blue hose at service port 3 way valve (port locate at left or right depent on manufacturer) you will get pressure about 40-45 psi(air cond is running) then use a allen key(hexagonal wrench) to close 2 way valve(small tube or gas discharge side) wait 1-2 minute then close 3 way valve (suction tube or big tube) IMMEDIATELY SHUT OFF AIRCOND AND PLUG OUT POWER CORD (you need 2 person one at in door unit and the other at out door unit). this method is to keep remaining gas inside the compresser.Then leak check ,open 2 way valve about 90 degree hold it for 10 minute then close it .MEASURE THE PRESSURE keeep it for 5-10 minute. If the pressure indicate not same during the first time measured it meant there have a leakage, for air cond 1- 5 year the leakage will happen at the copper tubing connection and improper flaring .Then U need to clean in door and out door unit ,used a spanner or wrench to losen the copper FLARE NUT at out door unit and in door unit( inside insulation) then use pvc tape to cover all copper pipe/tube hole to prevent dirt go inside tube/pipe. Then lift up out door unit and used coil cleanner ditergent wait 5 minute then flush with water. Remove indoor front panel then disconnect out door unit cable at front panel in door unit then lift up indoor unit to disangage the hook and pull out the indoor unit, then clean the cooling coil ,cover electrical part with plastic .last step u need to cut (used cooper cutter)the copper pipe/tube FLARE NUT connection low side(big tube) and high side(small tube) in door connection and out door connection .Then u need to remove the burr from cut edge using reamer make sure metal powder not goes in Then make a flare after inserting FLARE NUT onto the copper pipes Then U can install back the unit check the low side pressure if the pressure 55-67 psi no need to charge

Posted on Mar 23, 2010

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  • shahraimi Mar 23, 2010

    then check gas leakage using same method that already explain.suction pressure 55-67 psi in running mode and set to lowest temp(16 degree celcius) If not u need r22 gas tank, connect yellow hose to r22 tank and middle connection at test gauge .Then fully open tank valve and crack open blue stem at test gauge (DO NOT exceed 100 psi to prevent flooding the compresser) for 30 second to 1 minute then close it, measure the pressure for 1-3 minute.Repeat this step until u get 67psi in running aircond or u can feel suction pipe/tube cool.If your unit alreday empty u need r22 lubrication and weigth scale put r22 gas tank on scale and read at out door unit tag how weight recomended by manufacturer ,Then u need to fill yellow hose with r22 lubrication about 5-10 mililiter .Then repeat charge method that alredy explain and measure the weight of the gas and done

  • shahraimi Mar 23, 2010

    What is "Super heat"?

    You will hear and see this term all the time in reference to refrigeration. Simply put it is the difference between the temperature of a vapor line in relation to the temperature scale on a pressure gauge for a particular refrigerant or how much liquid is feeding the evaporator in relation to how fast it is being boiled off. for example (R22) if the suction gauge reads 70 psig then the evaporating temperature is 41 degrees but if the tubing is 51 degrees then you have 10 degrees of Superheat. A typical range for residential air conditioning is 8-18 degrees with some error based on extreme conditions. Once you understand Superheat you can diagnose obvious problems. For example a system that is under charged or has a stuck (closed) metering device will have high super heat (over 20 degrees) at the compressor and a system that is grossly overcharged or has a dirty indoor coil will have very low Superheat about 3-7 degrees with low suction pressure and the suction line will be very cold. It is ok and quite normal for the Superheat to change dynamically while the system is running, you will have to interpret what you are seeing.

    What is "Sub cooling"?

    Sub-cooling is similar to Superheat but happens in the condensing portion. Refrigerant when condensing will happen at a particular temperature which is very close to the temperature scale corresponding to head pressure for a given refrigerant. After the refrigerant is condensed it will try to assume ambient temperature but will never reach it. The difference between liquid line temperature and condensing saturation temperature is Sub-cooling and is a very good indication of "refrigerant level", but only when proper Superheat is indicated or you could have a misleading indication. Typically 20 degrees of Sub-cooling is desirable and the closer the liquid line temperature is to ambient the better (indicating an efficient system). Checking Subcooling in the heat mode of a heat pump has to be done carefully because you have influence of the space between the indoor coil and the point of measurement. For best heating you will want most of the refrigerant to be condensing in indoor coil without backing it up with refrigerant.

    As a general rule Subcooling = Refrigerant charge quantity, Superheat = Refrigerant cycle performance. Check both!!!

  • shahraimi Mar 23, 2010

    u need to purge air inside piping/tubing by using leakage check method but just used service port no need to used test gauge crack open 2 way valve for 10 second then close it then push the pin(same like tyre pin) at service port 3 way valve for 3 second repeat this three times also u need to purge all air inside test gauge and hose


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Hook up your gauges to the unit charge to proper super heat and sub cooling Or to that data plate specs. oh ya purge all of your hoses of air I call somebody with a license and have it properly serviced. Tom

Posted on Jul 03, 2009


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