testing AC in winter?

[Andrew W. Hinz]

I have heard that there is a way to test the AC in the winter without risking damage to the compressor. Has anyone heard of this or know how to do it? Thanks.

[Tim C. Howell]

Not me Andy. I do not test them in the cold weather. It is different than a heat pump, but I'm not sure how it is different. sorry, not much help

[Andrew W. Hinz]

When temps are below 60, I don't test them and mark it in my report. However, I was on one of these free conference calls with Mike Crow and he briefly mentioned something about this and it sparked my interest.

[David A. Andersen]

Yes there is.

Are you EPA certified to handle ozone depleting agents?

You need to access the refrigerant circuits on the equipment to do this.

[Andrew W. Hinz]

Wow. No, I'm certified in a number of things, but ozone depleting agents is not one of them. Sounds like for the average home inspector, the AC is off limits come winter time.

[Larry J. Michael]

Never and most HVAC techs won't do it either.

[Wayne B. Wilson]

Originally Posted by dandersen

Yes there is.

Are you EPA certified to handle ozone depleting agents?

You need to access the refrigerant circuits on the equipment to do this.

LOL i do have that one, mine was good international actually . i have had it in 1996 i think, ill have to find it

[Eldon E. Holliday, Jr.]

Someone please post this restriction of no test below 60 degrees from a manufacturer. A/C units run with outside temps below 60 all the time. This rule only relates to units with no power supply within the last 24 hours and temps below 60 degress within the last 24 hours.

[ROBERT W. NEWLAND, JR.]

I don't but I always think of a family get together at thanksgiving with everyone in the kitchen cooking and someones says, "it's hot, turn the air on". Never heard anyone say, "wait! What's the outside temperature?!" You would think there would be some kind of cautions in the owners operating manual but I haven't seen one. Still I don't test.

[David A. Andersen]

Besides Tim, we all live in the tropics in comparison to many!

For those that do "turn on", what/how do you evaluate the test?

[gkay]

Originally Posted by eholliday

Someone please post this restriction of no test below 60 degrees from a manufacturer. A/C units run with outside temps below 60 all the time. This rule only relates to units with no power supply within the last 24 hours and temps below 60 degress within the last 24 hours.

It is not that you can’t run them it is more that you are operating them outside the normal design parameters. Typically (if you use your head) there is no need for air conditioning if outdoor ambient is below 70. (78 by my personal comfort zone not taking into account Relative Humidity) and I personally won’t evaluate them as a Home Inspector below 75 F outdoor and a minimum of 75 F indoor because you need the indoor heat loads, the main reason we all have air conditioning.
Many air conditioners are equipped with factory installed low ambient controls to prevent operation in low temperatures while with others it is an advisable option.
So if the a/c doesn’t start are you going to determine that the low ambient control is stopping it or are you going to bypass this control to determine if the a/c is operating satisfactory? Or are you going to assume that it is not responding to the thermostat and recommend further evaluation? Or are you going to say it is operating ok based on what,,,delta T?
Yes air conditioners do run at temperatures below 60 with the proper accessories and depending on humidity they will utilize an economizer section for “free” cool air or the use of a head pressure controls to maintain reasonable operating pressures.
You are correct, the manufacturer does not say NOT to run below 60 BUT the references and tables given by the manufacturers to trouble shoot and diagnose is typically limited to a temperature range of 60 degrees F to 115 degrees F. Any adjustment of refrigerant outside this range is not recommended. Furthermore manufacturers recommend that operation below 60 F only with the use of appropriate accessories.
Now given that, even if you have a heat pump (which does run in low ambient) that requires a refrigerant adjustment, a tech may ESTIMATE an adjustment of the refrigerant charge based on temperatures, pressures, installation and operating characteristics of that particular unit BUT the corrected charge should be re evaluated under normal air conditioning operating conditions typically 85 to 115 outdoor air.
If you need residential air conditioning temperatures below 60 it’s called a walk in cooler, refrigerator or freezer. If you have an indoor load that requires air conditioning in a home when outdoor conditions are 60 or less open a window.

Note temperature ranges on tables below. I don;t think the tables stuck to this.

[staylor5]

When an ac is installed, the outside temp needs to be above 65 degrees in order to calibrate it with the proper head pressure. maybe that has something to do with it.

[Eldon E. Holliday, Jr.]

Robert you give a perfect example, often times in my area the overnight temp could be below 60 and easily be in the 70-80 during the day. Steven I agree that a minimum temp is needed during installation. Now to Gordons post what if you decided not to test the unit because the outside temp ws 72 degrees, after closing the buyer finds the compressor is locked. What facts will you base the 75 degree min. temp on.
I would like for someone to post something from the manf. stating do not test below a certain temp.

[Richard W. Washington]

An HVAC tech. told me that that the oil in the condensing unit cannot circulate properly when the outside temp is below 60 degrees.

[Mark E. Northrup]

Originally Posted by rwashington

An HVAC tech. told me that that the oil in the condensing unit cannot circulate properly when the outside temp is below 60 degrees.

that is what i have heard that the compressor may overheat becuase of the oil is not circulating or not there.
Mark