AC freezing up from being set too low?

[Hobby_Man22]

I had the ac set to 71 and according to my fieldpiece temp meter it was keeping the shop at 69.5-70.0 degrees the entire time. The ac pretty much ran the entire time while it was 95 outside. It turned off a couple times though and when it turned off I could hear what sounded like a bunch of water flowing into the drain pan. I went up there to see and the coil was dripping slightly, but there wasn't really enough water in the pan for it to even make it to the secondary drain. The water was draining out of the drain pipe so I don't understand. The system is new and just had the charge level checked a month ago so it's not low on freon. Thought maybe since it was running for 3hrs straight it was freezing up.

 

[rlitman]

At those outside temperatures, it should not be freezing up from just setting it too low.

Testing charge a month ago is NOT confirmation that it is not low now. However, I would start with the basics. Check the filter and if the filter is clean check the evaporator coil. Low flow over the evaporator (could also be a blower issue) can cause freezing.

 

[slow]

running 3 hours straight will pull out a lot of humidity, 71 set temp in 95 degree weather and running all of the time, sounds like expected operation. like the other poster asked, how is the airflow, I have had issues with freezing due to airflow restriction

 

[Hobby_Man22]

At those outside temperatures, it should not be freezing up from just setting it too low.

Testing charge a month ago is NOT confirmation that it is not low now. However, I would start with the basics. Check the filter and if the filter is clean check the evaporator coil. Low flow over the evaporator (could also be a blower issue) can cause freezing.

True but it was installed back in November and when they checked a month ago it still had a full charge.

 

[Hobby_Man22]

Everything was running fine, air coming out of the vents etc. First time I had it set that low for that long though. Was kind of doing a shakedown to see how it would perform. Usually if I show up in the afternoon it will never get that low or it will be evening time and cooled off outside by the time it gets to that temp if I turn it down in the afternoon.

 

[Hobby_Man22]

Line might have a clog in it I guess. I blew it out with compressed air. Probably should have done the part with the little gooseneck also and not the one ahead of it, but it was flowing water so I left it alone.

 

[Hobby_Man22]

Do you think it might just be sweating? Or creating more condensation than can flow out of the drain?

 

[Gizzi]

At those temps and set points your coil shouldn't be freezing. Check filter and air flow. If those check out good, I would suspect a charge issue.

 

[theoldwizard1]

Line freeze ups are common when the charge is low.

 

[Hobby_Man22]

Maybe it needs more vents. It has 6 vents on a 5 ton system. 32' of 18" spiral ductwork. They blow good you can feel it across the shop.

 

[Hobby_Man22]

Actually the last 10ft goes down to like 12"

 

[Yankeefarmer]

I had the ac set to 71 and according to my fieldpiece temp meter it was keeping the shop at 69.5-70.0 degrees the entire time. The ac pretty much ran the entire time while it was 95 outside. It turned off a couple times though and when it turned off I could hear what sounded like a bunch of water flowing into the drain pan. I went up there to see and the coil was dripping slightly, but there wasn't really enough water in the pan for it to even make it to the secondary drain. The water was draining out of the drain pipe so I don't understand. The system is new and just had the charge level checked a month ago so it's not low on freon. Thought maybe since it was running for 3hrs straight it was freezing up.

After reading this over and over, I don’t see where you are having any problems. Is it possible you are just hearing water running into the drain because it’s quiet when the system shuts off?

 

[Wrench97]

Condensate is normal, the more humid it is outside the more you are going to get in the drain line
If you are using one of those thick high merv number filters stop the system will run better on the low merv # filters like a merv 4.

 

[metlmunchr]

Is the drain line trapped where it exits the unit? If not, then the unit will hold water in the drain pan to a depth equal to the negative pressure in the unit. You've said before that this is a heat pump system, and they are typically draw thru units so the coil and drain pan are on the negative pressure side of the fan. Additional restriction on the entering side, like a high merv filter for example, will cause the water level in the pan to stay deeper while the unit is in operation. Once the fan shuts off, all the condensate held in the pan drains out. A trap in the drain line stops this from happening.

 

[Showkey]

If the evaporator coil is freezing ( frozen) the building will stop cooling ( aka getting warm).

The AC system should be pulling gallons of water per day out of the air.

Sounds like your system is working…….as long as the water is draining.

 

[The Cobbler]

OP needs to clarify what he's getting at ,IMO.
the title asks if AC freezes if set to low, but no where in the post does he say there's ice on anything, and his indoor temp is cod. if it was freezing, as mentioned , it would not cool

 

[Hobby_Man22]

It's working. I guess the primary drain just has a small clogg in it then. It's not supposed to drain into the secondary drain Pan.

 

[Hobby_Man22]

I'm not talking about the condenser pan I'm talking about the pan under the entire unit.

 

[rlitman]

It's working. I guess the primary drain just has a small clogg in it then. It's not supposed to drain into the secondary drain Pan.

They usually get a buildup of algae in the trap over time. Blow it out, and add pan tables to the internal pan to prevent the algae.

 

[Hobby_Man22]

The water was flowing when I looked into the pipe. I'll blow it out though.

 

[Hobby_Man22]

They usually get a buildup of algae in the trap over time. Blow it out, and add pan tables to the internal pan to prevent the algae.

When you say trap are you saying that part of the pipe with the dip? So that's the part that keeps the water from draining after shut off?

 

[Git]

Is the drain line trapped where it exits the unit? If not, then the unit will hold water in the drain pan to a depth equal to the negative pressure in the unit.

That was my thought also

When you say trap are you saying that part of the pipe with the dip? So that's the part that keeps the water from draining after shut off?

- this video explains it pretty well

 

[rlitman]

When you say trap are you saying that part of the pipe with the dip? So that's the part that keeps the water from draining after shut off?

Yes. It's a drain trap. Got a picture of your setup?

The trap in the video above is a REALLY nice one that's super easy to service. Being clear is good visually to see if it is clogged, but clear also lets light in, which can lead to algae growth, so that part's a double edged sword. But having a T on both ends of the trap that allows you to easily snake it is what makes that one easy to work on. Many are missing this detail, which is why I'm asking if you have a picture of yours.

 

[BillK]

Everything was running fine, air coming out of the vents etc. First time I had it set that low for that long though. Was kind of doing a shakedown to see how it would perform. Usually if I show up in the afternoon it will never get that low or it will be evening time and cooled off outside by the time it gets to that temp if I turn it down in the afternoon.

I dont know your entire setup or how often you are in your shop but I have learned over the years that it is actually less expensive to just leave the thermostat set at around 75 degrees and let it run 24/7 If you turn it off when you leave then everything in the shop including the floor slab starts to warm up. Then when you turn the AC back on it has to run forever too cool everything back down. Same goes with the heat in the winter.

Personally I would feel frozen at 71 degrees. It has been in the mid to high 90's here for the last week or so and I have the AC at the shop set at 75 and it is perfectly comfortable.

 

[Showkey]

Hobby man ……how much is electric bill per month ?

 

[Terry D]

So you are saying that you did not actually see anything freezing up. You are just seeing a lot of water coming out when it shuts off. It sounds like this is the first season for this unit running in the summer. Your drain would not be clogged up already, unless of course it was not installed correctly. It sounds like they installed a trap. The purpose of the trap is to isolate the air flow inside your evaporator from the air outside the unit. It there was no trap, it would want to **** air in through the drain, and then you pan would not drain right and over flow. Having more water coming out of that drain when the unit shuts off is ok. The main thing is that the pan is not over flowing. You live in a high humidity area, there is going to be a lot of water coming out. Are you leaving this unit on all the time or just when you are out there. Keep it set at 75 or 76 all the time, then you could bump it down if you want when you go out there. If you are not seeing any ice, there probably is nothing wrong with the charge or air flow. If it is cooling the building down to where you have it set at, I don't see anything wrong. A properly sized unit will actually run for longer periods of time during the heat of the day to remove humidity, you want that, if it cycled a lot, it would not properly remove the humidity and always feel clammy in there.

 

[Wrench97]

So you are saying that you did not actually see anything freezing up. You are just seeing a lot of water coming out when it shuts off. It sounds like this is the first season for this unit running in the summer. Your drain would not be clogged up already, unless of course it was not installed correctly. It sounds like they installed a trap. The purpose of the trap is to isolate the air flow inside your evaporator from the air outside the unit. It there was no trap, it would want to **** air in through the drain, and then you pan would not drain right and over flow. Having more water coming out of that drain when the unit shuts off is ok. The main thing is that the pan is not over flowing. You live in a high humidity area, there is going to be a lot of water coming out. Are you leaving this unit on all the time or just when you are out there. Keep it set at 75 or 76 all the time, then you could bump it down if you want when you go out there. If you are not seeing any ice, there probably is nothing wrong with the charge or air flow. If it is cooling the building down to where you have it set at, I don't see anything wrong. A properly sized unit will actually run for longer periods of time during the heat of the day to remove humidity, you want that, if it cycled a lot, it would not properly remove the humidity and always feel clammy in there.

I think he is saying he has water in the pan under the unit(I.E. the condensate line is plugged or the unit is leaking)

I'm not talking about the condenser pan I'm talking about the pan under the entire unit.

 

[Hobby_Man22]

Hobby man ……how much is electric bill per month ?

Just got the bill. $41.60 I just run it when I'm inside.

 

[Hobby_Man22]

I run a dehimidifier when I shut the ac off otherwise their would be 85 percent humidity inside and would probably have moisture dripping from the ceiling.

 

[Hobby_Man22]

I still think the secondary drain pan should br dry. It has a float switch that shuts the unit off when it gets too high.

 

[Wrench97]

I still think the secondary drain pan should br dry. It has a float switch that shuts the unit off when it gets too high.

Yes it should be dry, it is there as a back up so leaking condensate does not damage interior finishes.

 

[Git]

Did you ever verify that you have a proper trap in your primary drain line that would prevent the condensate from being sucked back in when the ac is running instead of allowing it to drain out?

 

[u3b3rg33k]

I had the ac set to 71 and according to my fieldpiece temp meter it was keeping the shop at 69.5-70.0 degrees the entire time. The ac pretty much ran the entire time while it was 95 outside. It turned off a couple times though and when it turned off I could hear what sounded like a bunch of water flowing into the drain pan. I went up there to see and the coil was dripping slightly, but there wasn't really enough water in the pan for it to even make it to the secondary drain. The water was draining out of the drain pipe so I don't understand. The system is new and just had the charge level checked a month ago so it's not low on freon. Thought maybe since it was running for 3hrs straight it was freezing up.

are you sure you're not hearing the refrigerant flowing/boiling off? that can sound like water.

 

[Hobby_Man22]

Did you ever verify that you have a proper trap in your primary drain line that would prevent the condensate from being sucked back in when the ac is running instead of allowing it to drain out?

It does. It's has that little low spot with a 6" stand pipe that's also capped off. Also has another standpipe about 6 inches down the line. And that one is open. It also has a shut off valve I guess to aid in blowing out any clogs.

 

[Wrench97]

The shut valve is a bit odd, do you see a steady drip out side from the end of the line?

 

[Terry D]

OP, can you post some pictures of the condensate drain. Has this unit been running all season and just started giving you problems now.
Are you saying you have water in your safety pan, plus there is water coming out of the drain. Which drain are you talking about.

 

[Hobby_Man22]

OP, can you post some pictures of the condensate drain. Has this unit been running all season and just started giving you problems now.
Are you saying you have water in your safety pan, plus there is water coming out of the drain. Which drain are you talking about.

Yes water in the safety pan and the coming out of the main drain which of course is normal. The safety pan has a drain too. The pan barely has enough water to reach the drain, so it's not like I have an inch of water in the pan. I'll post some pics.

 

[Terry D]

Yes water in the safety pan and the coming out of the main drain which of course is normal. The safety pan has a drain too. The pan barely has enough water to reach the drain, so it's not like I have an inch of water in the pan. I'll post some pics.

How long has this system been in service, all season or just a month ago. why was the charge checked a month ago. You could have too much air flow across your evaporator causing it to not drain properly. I would call back who ever installed it

 

[Hobby_Man22]

I'll blow out the trap and see what happens. I blew out the other drain further down, but I guess I need to blow out that goose neck thing too. I saw water flowing in the pipe after that so I thought it was fixed, but I guess not.

 

[Hobby_Man22]

How long has this system been in service, all season or just a month ago. why was the charge checked a month ago. You could have too much air flow across your evaporator causing it to not drain properly. I would call back who ever installed it

All season.