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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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A/C internal unit freezing?
Hi,
One of those small wall mounted Season A/C units suffering lots of ice formation upon the heat exchanger matrix. The diagnosis is that the system needs to have the gas topped up. Being as I am the type of character who likes to understand the logic behind the diagnosis, rather than just accept it... Why does the ice form if the gas is low? My problem with the diagnosis is that if the gas were low, then surely the chilling effect on the internal matrix would generally be poorer. -- -- Regards, Harry (M1BYT) (L) http://www.ukradioamateur.org |
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In article ,
Harry Bloomfield writes: Hi, One of those small wall mounted Season A/C units suffering lots of ice formation upon the heat exchanger matrix. The diagnosis is that the system needs to have the gas topped up. Sounds like BS to me. It should have a temperature sensor on the heat exchanger to detect freezing, which should switch it off. Cause might be airflow blocked, or operating it when air temperature is well below its designed min operating temperature. -- Andrew Gabriel |
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Andrew Gabriel explained on 07/02/2005 :
In article , Harry Bloomfield writes: Hi, One of those small wall mounted Season A/C units suffering lots of ice formation upon the heat exchanger matrix. The diagnosis is that the system needs to have the gas topped up. Sounds like BS to me. ...and me too. It should have a temperature sensor on the heat exchanger to detect freezing, which should switch it off. Cause might be airflow blocked, or operating it when air temperature is well below its designed min operating temperature. They do sound like more logical reasons, thanks.. -- -- Regards, Harry (M1BYT) (L) http://www.ukradioamateur.org |
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"Harry Bloomfield" wrote in message ... Hi, One of those small wall mounted Season A/C units suffering lots of ice formation upon the heat exchanger matrix. The diagnosis is that the system needs to have the gas topped up. Being as I am the type of character who likes to understand the logic behind the diagnosis, rather than just accept it... Why does the ice form if the gas is low? My problem with the diagnosis is that if the gas were low, then surely the chilling effect on the internal matrix would generally be poorer. -- -- Regards, Harry (M1BYT) (L) http://www.ukradioamateur.org The temp drop is caused by expansion of pressurised gas into a lower pressure area through a fixed or sometimes (rarely) variable tiny hole. If the pressure after the hole is lower than it should be (due to low gas) then the expansion rate is higher and the temperature lower and the evaporator freezes. This is easy to prove by overfilling a system, whereby it ceases to work, since the high and low pressures are the same. Cheaper units do not have a sensor to detect ice build-up. Get an engineer to put the gauges on and the problem is very obvious. Or buy your own gauges and a bottle and fill it yourself. (read a book on safe procedures first.) mrcheerful |
#5
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mrcheerful
. brought next idea : Get an engineer to put the gauges on and the problem is very obvious. Or buy your own gauges and a bottle and fill it yourself. (read a book on safe procedures first.) Thanks for the explanation as to how, that does seem to hang together now. No need for me to worry about fixing it, a specilist engineer will attend to it. I just wanted to understand why it should happen and confirm we had the correct diagnosis. -- -- Regards, Harry (M1BYT) (L) http://www.ukradioamateur.org |
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