A/C pipes keep freezing

16 years ago

Here's my story:

Moved into a duplex about 2 months ago. When we first moved in the A/C didn't work at all, the unit wouldn't even come on. My landlords "A/C guy" is just someone who lives in the neighborhood. He came by and said the entire unit was blown. Fan motor, capacitor, everything. Took a few days but the landlord bought a brand new unit and got the guy to put it in (not replacing anything in the ceiling, just the unit outside). It worked well for 2 days, then just started blowing hot air. Checked the pipes outside and they were hot. A/C guy came back out and found that the people who had lived there before me installed their own thermostat and wired it wrong, so it was telling the unit to blow hot instead of cold. He rewired it and things were good for about a week. Came home one day and its 90 degrees in the house. Go outside to look at the unit and the bigger of the two pipes was covered in at least an inch of ice. While it's fozen, no air comes out of the vents inside the house, but I can still hear the ceiling fan running. Guy came back out and checked the coolant levels and checked for leaks, level was good and no leaks. I checked the filter inside the house and it was a little dirty so we blamed it on that and I bought a replacement. Turned the unit on heat to melt the ice and let it sit off for a while. After that it worked fine....for 3 days. Came home, same thing. House it hot, big pipe is frozen, no air coming through the vents. Called A/C guy back out, he "went into the attic and checked the coil" and said it was ok. Turned heat on, unfroze pipes, all was well for 3 more days. This is where I am now.

So:

Big pipe freezes

No air from vents

Fan in ceiling still runs

Filter is clean

Coolant levels are good and no leaks

This leads me to 1 conclusion. It's gotta be something in the attic. I've never been up there and honestly wouldn't know what i'm looking for. I've been in attics before (wired and entire house) but have no experience with central AC.

Any suggestions?

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Comments (4)

tigerdunes
16 years ago
teh

obviously, you need a true AC/HVAC certified tech. since outside condenser is brand new, leaks and/or low refrigerant have to first be eliminated as the cause. I don't believe you will get satisfactory help from neighborhood AC guy. ask your landlord to send another person. and while I know people do it all the time, it is always the best policy to replace both the outside and inside unit at the same time so you will have a matched system. and btw, there are proper methods for checking and locating leaks. is new unit R-22 frig or R-410a? was the lineset replaced or the old one reused? if old one reused, was it cleaned before the recharge? propablt not. sounds like a rental hack job.

IMO
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bf-tx
16 years ago
Agreed.

A unit doesnt run then not run, then suddenly have a mis-wired stat.
Inexperienced installer with no doubt bad install is grasping for explanations
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vstech
16 years ago
heh. I like that it worked fine for 2 days, then the thermostat was telling the unit to run heat... amazing morphing tstat!
there are two things that will cause ice in a running a/c system. airflow and freon charge. if the fan cuts out during the day, then comes back on, you can freeze up the coil and then the fan blowing will do no good. are you SURE he is not putting freon in when he checks the system?
another odd possibility is there could be debris in the lineset that flow normally when you shut down the system to melt the ice, then flow over to the flow control and cause a blockage. if you are SURE he is not putting in freon, and you are SURE the blower is turning 100% of the time the system is running, it could be debris.
another possibility occured to me... is the outdoor system larger than the indoor system... I mean are they mismatched tonnage units? if the flow control device is undersized for the outdoor unit this could happen too. but the pressures would be waaaay off during charging, so only an idiot would not notice it during the installation... plus most outdoor units come with the proper drill size orifice to install in the coil... assuming the same brand coils are used.
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johnsteve_2008
16 years ago
Everybody should service our A/C at least once in 3 months.If they do this cooling will be good and life our A/C also good.
===================================================

john

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