Is It Too Cold Outside to Run My AC?

early spring

An interesting question, asked and answered on The Wall:

Hi All,

I’m new here and hope that you can help me with some questions.

I just had a Heil H4A836GKD / FVM4X4800A (3 ton) installed in my home at the very end of March. A couple of weeks ago it was fairly warm for April in New England and our inside house temp was about 75 degrees. Outside temp was about 63-65 degrees maybe slightly lower. Because my wife has bad allergies and I was anxious to try out our new AC I decided to turn it on. It came on for about three minutes, and then it turned off for about two minutes, and then it came back on for about five seconds. This cycle of off for about two minutes and on for five  seconds continued. I had my AC on, but my house was getting warmer. I went on the Internet and what I read made it sound like it was cycling and that it was best for me to turn it off and call the company who installed the unit. So I turned it off and called the installer on Monday (this all happened Friday evening. It was by no means an emergency so I waited until Monday to call). 

We were told they could come out in a week and a half to test it – this was a little annoying considering we had paid good money for this and the first time we go to use it it did not work – but it is not the heat of the summer yet so I can be patient. They were supposed to come yesterday but they called and said it will be too cool for them to test because it is setup to not operate below a certain outside temperature (it was only about 60 degrees for a high yesterday, maybe not even quite that high). 

Here is where I am running into a wall. They either would not, or could not, provide me with the temperature below which the unit will not operate. They then proceeded to tell me the day I tried to run the unit that it was probably too cool outside, and that is why it would not run properly. Is 60* too cool for my AC to run? 

Can anybody provide me with the temperature at which my AC will not run because it is too cool outside? And is it possible to lower this cut-off temperature if necessary? I ask because this could potentially be a problem for us because on sunny days our house can run 10 to 15 degrees hotter inside than outside and simply opening windows will not bring the inside temperature down to the outside temperature. Also, as I said, my wife has bad allergies, and one of the reasons we purchased the system was to try to keep the windows closed, more often so we can ease her suffering. So it is conceivable that on a very sunny, 70-degree day, it could be 85 inside the house (that would be extreme but not beyond the realm of possibility). If we cannot run this AC at 65 degrees outside, we could potentially have a system that does not fully meet our needs. 

I have tried to find documentation for this system that would provide this information but have I have been unsuccessful. 

I called yesterday and asked to speak to the owner of the business because his assistant initially called to reschedule because it was going to be too cool yesterday. They wanted to reschedule for tomorrow, which seemed silly because tomorrow's high looks to be very similar to yesterday’s high temp. I can’t keep rearranging my work schedule so I can be at home, only to have them continually reschedule because it is too cool out. I just wanted to know when and how this would be fixed. 

During our conversation, he mentioned that the units are often shipped to them undercharged, and that it may need to be charged. They were unable to determine if it was adequately charged at the time of installation, due the low outside temperature (again it was March). He stated that when we get a day “warm enough” (I’m still unclear what warm enough equates to in degrees Fahrenheit) they could come and evaluate the system and charge it if needed, and this would most likely take care of the problem. 

Does that sound reasonable? 

I got the feeling he just wanted me off the phone, and I don’t know if I should believe what he was telling me. 

I want to believe him. He came very highly recommended, and on the day of the install everything went very well, and his crew was very professional. 

So at this point I am just trying to educate myself as much as I can because he seemed unwilling to help educate me with regard to exactly how the system should work and what my expectations should be. 

I am still hopeful that it will all be taken care of fairly easily but I want to be as educated as I can just in case he is feeding me a line of BS. 

Thanks in advance for your help.


Paul Fredricks comments:

I think 65° is the lowest. When you say it turns on then turns off, then turns on, are you talking about just the outdoor unit, or the whole system? I suppose if the charge is low, or if it's cool out, the outdoor unit could cycle on pressure, but the indoor fan should stay on the whole time. If the indoor fan is cycling on and off like that, something else is going on.

Of course, I don't know what system you have or how it's wired, just my two cents.

I'd wait till it warmed up, like 70° to be safe. Then see what they find.

Ken answers:

Just the outside unit. Thanks for the reply. I am referring to the outside unit. The inside fan runs continuously. We have it set to run all the time. If we turn it off it turns off - no problem with the inside fan.

Icesailer jumps in:

"I" Think:

I think that the installer is a moron.

If the installation has been paid for (and even if it isn't), the installer should have run, not walked, to the job to check it out. Even if it was too cool outside. And I don't see that THAT was a problem. Just showing up and looking at the installation will make the customer feel like someone cares. Obviously, this installer doesn't care a lot because now that "I" know that the owner will post questions on The Wall, shows me that he knows just a little bit more than your average Ranger.

The fact that the installer suggested that sometimes, the units aren't charged enough from the factory and may need more liquid, WTF? They always need more liquid. That's what the gauges are for. Was it even filled upon install?

Because the company owner couldn't be bothered, he now has an upset customer. If the owner calls someone else and there is a problem, he won't be covered.

The customer wouldn't be posting here if the owner had taken the time to go by and put in an appearance. A good customer relations practice.

Don's thoughts:

Charging ac:

Well to be fair to my HVAC brother, personally I like to see more of a load when dialing in an AC unit. What I mean by load is higher outdoor- and indoor-ambient temps.

The reason why one does not like to charge with low loads are the refrigerant does not have enough heat to boil off the liquid to a gas, and the coil become flooded, sending liquid back to the compressor that could damage the compressor over time.and the possibility of the unit freezing up. Also many times you will find that on the charging chart, with low ambient temps, that the manufacturer does not list what the superheat and sub-cool temps should be.

The bottom line is that most units now come with TXV that maintain evaporator superheat, and one could also weigh in the charge for the customer that has to have it now.

Again, I prefer to wait until there is a greater load placed on the AC because I would like to see all the numbers with a wet coil verses a dry coil.I also like how much easier it is to dial one in with a load verses no load.

Empire says:

50 degrees F and above, I have no problems with it running or charging it. Below that temperature, it will need some kind of low-ambient control to keep head pressures up. Even when checking at 50* or 55*, the pressures across the board will be lower than desired, but the load should satisfy relatively quickly. If you are trying to keep your house below 70* when cool outside, you will have problems. Your HVAC guy should be able to help with the on off that you hear.

Ken again:

Thanks. While I agree the installer could have handled the situation better I am also glad to hear there may be merit to his explanations. He also should have done a better job setting my expectations. In no way did he ever indicate that they may have to come back and charge the system on or before the day of the install. This only came about after I called saying it did not work. They showed me how to operate the thermostat, and told me that if some rooms were too cold and some not cool enough that I should call and they would come and re-balance the system. This certainly left me with the impression that when I turned it on it would work without having to have them come out and add charge to the system.

Also with regard to the thermostat, the person who explained it to me did not fully understand its capabilities. He explained it as a 5-2 thermostat. The box indicated it was 5-1-1 which was preferable because our Saturday and Sunday schedules are very different, and we could befit from a 5-1-1. He stated that it was 5-2 and thought we would need a different thermostat for 5-1-1. He did not know why the box listed it as 5-2 or 5-1-1. Luckily, the electrician left the box and the installation guide (and not just the user's guide, which makes no mention of changing any of the settings via the service mode), which explained how to go into the service mode and program it to go into 5-1-1 mode. If I had not seen the box, I would have never known it was capable of 5-1-1. It was not the electrician who explained the thermostat operation. He had already left. I'm sure he would have known how to change the mode from 5-2 to 5-1-1.

Bottom line is I am relieved that this will probably be resolved with a visit after it warms up. The owner needs to do a better job educating and setting expectations for his customers, and do a better job educating his employees with regard to the operation of the equipment. I will provide him with that feedback in hopes that he will listen and do a better job going forward.

I don't want to make it sound all bad - there were many positives with my experience but of course it is the negatives that the customer tends to remember. I just hope he will take my feedback and use it to improve customer relations. But I can also say that I will not be referring any of my friends to him for future business.

Thanks to everybody here for your feedback. I has helped put me at ease. Much appreciated.

Techman's thoughts:

A simple explanation at the end of the install would have eliminated this minor problem, that being that we may have to come back in warmer weather to start and check the operation of the system. Now, that being said, the regular/normal/typical home AC is NOT designed/installed to operate when outdoor temperatures are lower than 65-70*. But they can be, if proper "low ambient" controls are added. Commercial applications of your unit have them installed so their AC can run properly in any ambient temp. Most manufacturers of residential AC put in only enough freon for "about" 25' of copper tubing. Longer distances need more freon to be added. Your system is a 13-SEER, and most 13-SEER units do not have a low-pressure safety control that is factory installed, but something is causing your unit to short-cycle, so maybe Heil does have that safety control. I will check that out.

Now, as to your wife's allergies. What was put into the AC system to relieve her discomfort? A super-good air filtration device or a UV light? The normal one-inch-thick air filters do a lousy job of cleaning the air of allergens. Keep us up to date on your situation. Now, if there was no conversation about your needing to run the AC when the indoor temps get warm, then I would give the AC guy some slack. But,when you called for service, I think someone should have responded IF you said "We need our AC on due to my wife's allergies." Then, the representative of the company should have told you about the extra/chargeable controls, AND then sent a technician to solve the problem. We have a couple of customers a year that want what you want. NO PROBLEM!

Ken again:

So it finally got warm enough for the installing company to come out and check out my system. It seems it is a faulty TX valve. It has to be ordered. It should be here next week.

It makes me feel a little better with regard to the owner basically telling me to clam down because it was most likely just too cool outside - WRONG it was (is) broken. Don't treat me like a child just fix it.

I'll let you all know when it is finally fixed.



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