View Full Version : a/c lines freezing up???
ive got central heating and air in my home. I noticed the other day that my tile was cold to the touch and sweating.. i went outside and the line going into the a/c was coated with ice!! i shut the a/c off and let it thaw. what ive noticed is that the indoor and outdoor units wont shut off together, one will keep running(thus freezing the line) what could be my problem? is it a switch of some kind or regulator? thanks, i just wanted to know if i could fix it , or at least know what the hvac guy is talking about,
i did a search and it sounds like a defective contactor.. how much do these run and can i do it myself?
Most often freezing of an A/C unit is due to not enough return air. Having said that - you could have a faulty freeze detector (not a technical term).
rabadger
05-19-2005, 03:41 PM
Is this a new home? How old is the unit. Has it been runing ok in the last few years?
Is the filter clean?
not a new home, unit is probably 20 yrs old, filter is changed regularly,it has been running fine,
I would start by checking the charge of the coolant.. if it's low I would consider replacing the unit. The old freon coolant is illegal to use now.
roger g
05-19-2005, 08:28 PM
What you mean "my tile was cold". Tile ????
As Rich said, frozen lines are usually due to poor return air flow. A dirty filter is only one cause. Dirt on the underside of you "A" coil. Dirt that got past your filter may have plugged your"A" coil (the cold thing in your furnace). Your blower fins could be so dirty they don't move enough air. Maybe the motor is moving too slow especially if it is belt driven. Make sure all your vents are clear.
roger
yes my TILE, on the floor because the line from my indoor unit to the outdoor unit runs under my tile and it froze causing very cold tile..
Sparks
05-20-2005, 06:15 AM
Is it just the line that's freezing or is it the indoor coil as well? Being that you need a License to play around with refrigerants and the fact that it can be dangerous, I recommend you call a service contractor if you're having problems.
rabadger
05-20-2005, 06:42 AM
Is this the fist time you have used it this year?
it did it last year as well at the end of a/c season
rabadger
05-20-2005, 10:27 AM
sounds like a possible internal refrigeration problem, or air flow problem. not a mechanical or electrical one in the condensing unit.
Call a service tech.
Sparks
05-20-2005, 10:30 AM
Well then I might be inclined to think it's due to operating the ac in a low ambient temperature, maybe. If you're running the a/c all night or whenever it gets cooler this may be the problem. This happens all the time with commercial units when the tenants just let the ac run all night cause they're not paying the bill and then the unit freezes up and they have no cooling when they come in the next morning. This is one of the reasons economizers are installed. When humidity and temperature levels are lower outside than they are inside the compressors stop and the economizer dampers open allowing outside air into the building rather than conditioned air.. Saves money and prevents freezing problems. If this is the case, stop doing this because liquid refrigerant will be allowed into the suction side of compressor leading to it's eventual demise. I don't know, of course, if this is your problem but just mentioning it because I've seen this a lot. There are head pressure controllers that can be purchased and installed to remedy this as well if needed.
no i dont let it run all the time ,,normaly it is set at 77 degrees and it does fine,, but when my mother in law comes down from new york and sets the temp at 68-70 degrees seems thats when it does it..??
rabadger
05-20-2005, 11:03 AM
Then don't let her do it. You are cooling off so much the unit is freezing because there is not enough heat and humidity in the air over the indoor coil for all the refrigerant to boil off. If you continue to let it happen the refrigerant in the large copper line that is causing the freezing will get back to the compressor and you will damage the valves. Then its new unit time. Get someone to wire in a remote duct stat so she can play with the thermostat and nothing happens. Or have a freeze stat put on the unit so it shuts down before freezing. That way she will not destroy the compressor.
People do that because they don't understand the refreigeration cycle and have gone most of their life with oversized units intalled their homes. An AC should only be able to pull a 20 degree temp difference from the outside temp to the inside temp and if it is not warm and humid in the home they will freeze up fast in mild weather. When the return air temp and humidity level reaches a certain point the A/C is freezing.
You will have to explane to her that the thermostat must be left alone.
GOOD LUCK!
Sparks
05-20-2005, 03:08 PM
Well said Rabadger, 20 degree temp. differential between outside and inside is the limit. Remember, it's not just the sensible heat (temperature) but also the latent heat (humidity) that counts. Humidity removal is the key, tell her to keep her hands off the stat, unless you got money to burn for a new compressor when it slugs with liquid refrigerant due to unrealistic user expectations.
well its doing it again and my mother in law is not here. it was set a t 78 degrees and froze up and stopped cooling... what the heck???? im calling a specialist. i let you know....
well i got a tech to come look at it and he had to pry the contact points loose with a screw driver. He replaced the contactor and its been doing good, but it still gets a little freezing at the outdoor unit...he says my evap coil may be dirty.. its doing ok now though.. he wanted 599 to clean coil. i dont think so.
rabadger
06-17-2005, 10:44 PM
600.00 TO CLEAN A COIL! Thats all day at 75.00 an hour. It should only take a max of 4 hours even if you had to pump the unit down and pull the coil. Is the filter clean? Is the blower dirty?
new filter, blower has a little bit of sut on it, one other thing the water drain was clogged BADD. I used the shop vac and sucked a bunch of gunk out and it drains good now.. seems to be working fine now with the new contactor, just a little haze of frost on the outdoor unit pipes. go figure.
rabadger
06-20-2005, 06:13 PM
If you had enough dirt off the coil to plug a 3/4" drain the coil must be dirty enough to freeze up.
Some how you have to make sure the coil and blower are good and clean before proceding.
how do i get to the coil to clean it?
rabadger
06-21-2005, 02:51 PM
If you do not see a removable panel to get to the indoor coil for cleaning you will have to call a qualified contractor.
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