65 degree rule for R-410A central AC units?

I’ve been contacted by a Client about a home warranty claim on a central AC unit that did not start when they moved into a house I inspected this winter, and could not run it because it was too cold during the inspection (mid 40s F, well below 65F), which I of course explained in the report.

That house had a unit with freon refrigerant, and I’m familiar with the reasoning why not to run such units below 65F/18C, but this got me to wondering if the same applies for R-410A units, so I’ll know by this fall? I did a search and could not find anything.

FYI, the company is denying the claim because the unit did not run for my Clients. So even if something runs fine during the inspection it still might not be covered. Perhaps if my clients said it was running fine, and crapped out, it might have been covered. Always read the terms, warranty companies are very clever at disclaiming everything. Another reason I don’t get involved with home warranties in my inspection business.

I recently couldn’t run the furnace because it was 93 I the house. Thermostat only went up to 88.

Who provided the warranty? The agent?

Unless the SOP changes, would it matter?

Perhaps it may be time to revise the SOP ***if ***they’re outdated regarding this matter. Things change.

R-410A is a different refrigerant. It stands to reason it might not behave quite the same.

I’m hoping someone has technical insight into the matter.

#1 how you know it had “Freon” refrigerant?

#2 insurance company is not responsible for pre-existing conditions.

Your inability to operate the equipment at 40° screwed your client over.

#3 the reason you can’t find anything on operating R-410A below 65° is there is no such rule.

It makes no difference what type of refrigerant you have. It’s all about the equipment that it’s in.

I know you don’t want to hear it, but there’s no reason why you could not have operated the thermostat at 40°F. At least you could have gotten your client insurance coverage because it operated before they purchase the house.

The problem with the unit as it does not turn on. You did not turn it on, so no one knows.

Good job!


Joshua, Unless the SOP changes, would it matter?

What SOP says you will not operate an air conditioner at 40°F? It only says that you cannot do anything that will potentially damage the equipment. Well, turning on a light switch or flushing a toilet could potentially damage the equipment! So what’s the purpose of us being out there?

What if the deal falls through and the owner has an AC unit that no longer works? Who would they blame if it was turned on when it shouldn’t be according to the SOP? I’m far from a SOP wuss, but in this case the SOP makes sense for a very typical mid 2000s AC unit to which the question itself did not apply.

This from your own web site, danderson:
It is my recommendation that if you live in a cold climate and you are quite sure that the equipment was shut down for the winter and hasn’t been started recently, that you do not run the equipment until things warm up. Just because the temperature falls from 70° to 60° overnight and the temperature has not risen back above 60° for 24 hours does not create the situation we are talking about here. Refrigerant to oil migration does not occur in a matter of hours.

The inspection was done at about the time of the high temperature for the day. In the mid 40s.

This reminds me why I don’t log in here often. Can’t even get a straight answer to a question without people spewing their insecurities all over.

You can run it.

OK, so a R-410A split-system compression unit is OK to run under any conditions, rlewis5?

I do!
I’m in Florida.

I’m in Michigan, where it gets, way, way colder. Have done inspections when it barely got above 0F, including unheated buildings, which had electricity, but the gas turned off. How cold do you run them to in Florida, rlewis5? Quite a different ballgame here.

So, let’s say I’m doing an inspection on a house that has a typical split-system AC unit with freon refrigerant in 40some degree weather, bring a space heater, and heat the area of the unit and refrigerant line. How long I have to heat the area to 65F to run an AC unit with a great degree of defensible certainty it wouldn’t cause damage that could come back on me if a deal falls through and an AC unit that previously ran does not? Or would it just be foolish to do such a thing? Agents here know AC units are not to be run when it’s below 65 and as been for some time. Any insight from fellow northerners?

#1 40° is not cold.

#2 all you have to do is heat the bottom of the compressor, nothing else.

#3 there is a difference between “testing” and “operating”.

#4 you’re sitting here arguing, but you can’t even answer your own question. Obviously, you don’t know what you’re talking about or you wouldn’t have asked. A refrigerant is a refrigerant. All refrigerant has an affinity for oil.

The only reason that I am a home inspector today is because real estate agents in my area needed to know if air conditioners would run when they sold the property so they didn’t have to buy their clients new air conditioners. Home inspectors refused to start the equipment below 65°F. I have been starting air-conditioners in every climate zone in the world for 30 years and I have yet to have a compressor failure occur.

Again, there’s a difference between running and testing. Yes you will blow the oil out of the compressor when the unit is been sitting around in below freezing temperatures for extended periods of time. But seeing you are not “running” the equipment out of oil for any extended period of time, it will all come back to the compressor when it is turned on again once the weather warms up. The refrigerant system of an air conditioner is saturated in oil anytime it operates. Do you start your truck when it’s freezing in the great White North? If you do, you are running your engine without oil for a short period of time. Do you have an oil heater in your truck? About 90% of all air-conditioners out there have one. Maybe you should be more concerned about your truck!

Operating an air conditioner for extended periods of time in low temperatures outdoors lowers the suction pressure to a velocity where the oil will not return to the compressor and will run dry. Also, under low ambient conditions “indoors” does not provide sufficient load to change refrigerant from a liquid to a 100% vapor.

Nobody is telling you to analyze the performance of the HVAC system. They simply are asking you to turn it on and see if it responds (just like a lightbulb). If you do, then your client won’t get screwed by the insurance company!

This is simply my point, you screwed your client because of your SOP. Live with it. I would rather blow up a week compressor that was about to fail anyway before they close escrow.

It’s a judgment call. Unfortunately that requires some common sense.

Your post lacks sufficient information. You said it was 40°F. You didn’t say how long. You didn’t say what the nighttime temperatures were. You didn’t tell us the indoor air temperature from the heater being on before you tried to test it. You didn’t tell us of the compressor had a crankcase heater (you can see it without taking anything apart).

You do not get much useful info running a Heat Pump/AC when ambient is in the 40’s.

(unit went on, did it get cold??? who knows it was already cold everywhere else :p)

Warranty companies have some of the most Consumer Complaints of anyone, not my problem.

Like Brian said …

Frank …

410 is a blend and has to run longer to allow blends to mix, etc BUT your SoP would not be different on testing. You either DO or YOU decide to DO NOT test below 60 degrees.

I’ve charged units in March when the temp was 40 degrees one day / 60 the next. Its done all the time BUT …

At 40 degrees you do not get a very accurate heat load (plus if it was 40 degrees when you were there it may have been below freezing the early am) … NOT unusual to get 11-12 degrees TD and as a NON hvac technician WHAT do you tell your client then. AND eventually you’ll run one at 40 degrees AND a day or 4 later it craps out AND the Realtor, home owner, or hvac tech will be quite willing to throw you under the Bus. OR they’ll call another home inspector who follows the SoP to the “T” and he will be quite willing to SHOW everyone where the SoP says …

25 years ago lets say we used compressors with internal reed valves AND they most often had crankcase heaters around the compressors AND we were worried about sending COLD freon with oil in it back down the Suction Line into the compressor AND damaging the valves (blown compressor) … So we said DO NOT run the AC when temp is BELOW 60 degrees.

Then came scroll compressors AND its not that type issue anymore … BUT

Bottom Line PICK what you gonna DO and Then Do It.

BY the way … 1 other thing. In your report you told them that due to cold temperatures you could not properly run or test the AC unit AND therefore you knew NOTHING about its condition AND you recommended them having a competent HVAC contractor evaluate and check it prior to close. THEY then voluntarily chose to ignore YOUR advice AND you are sorry for THEM, but it AIN’t your problem. You can advise them to go at the seller for FAILING to disclose his/her non working AC unit.

I was waiting for this…

There is only a handful of you out there that can do a heating/cooling performance check of a running HVAC Unit.

Taking a Delta-T is not a performance test. It is not required of HI’s. What “IS” Required is **If it turns on with normal operating controls!

**That’s it. You are not qualified to do anything more.

In this case if you turned it on, you would have saved the client $$$.

Warranty: you don’t need a Home Inspection if you have a BS Home Warranty or By-Back now do you? Wrong!

And for the record, yes you can do a performance test of HVAC cooling in the winter. You just need to know how and have a proper Certification to work in HVAC. But this is not the point.

The point is; Will this thing turn on?

Personally I don’t give a crap if you run them or not. But I’m not going to sit silently by and listen to you ***** about your clients complaints and how worthless a warranty is (even though they are). If you want to run with the “Old Wives Tale” of the 65F thing, then just suck it up when your client gets pissed.

Your HI Report gave the Warranty Company it’s way out. And it is Legitimate.

Not picking on you Dan but this is for everyone!

Home inspectors cannot operate HVAC equipment below 65°F. What you are going to recommend further evaluation by a competent HVAC contractor evaluate it?

Somebody please explain how the HVAC contractor evaluates its operation when you can’t started when below 65°F?!

Delay closing till summer?

How should we as HI’s do it David?

#1 if you know nothing about HVAC then you should stick with the cold weather (65°F is not cold weather) scenario.

#2 if you took NACHI training courses on HVAC, you should visually inspect the equipment, considering its age, type of equipment, is there a crankcase heater, is it a scroll compressor or a reciprocal, what has the temperature been like in the previous 48 hours, is the house occupied or vacant. If the equipment is not a total catastrophe (which requires replacement anyway), operate in the heating mode and increase the temperature within the building to provide a moderate heat load. Then turn on and verify that the compressor and fans operate. Turn it off.

#3 during the summer months if you really want to get fancy and become worthy of being called a “certified home inspector”, you can conduct a heating/cooling performance analysis with just your hand. The temperature receptors in your hand are actually more sensitive than the most expensive thermal imaging camera. You can very easily determine temperature differential by simply “laying hands on the equipment”.

Listen to the airflow entering the return register.

Put your hand in the airflow of the supply register.

Feel the suction refrigerant line at the outdoor unit or compressor.

Feel the liquid line leaving the outdoor condensing unit or at the metering device inside the unit (do not touch the discharge line of the compressor). Too hot to touch is a dirty condenser coil (even if it looks clean). If the outdoor ambient is below 95°F optimally you should not feel any significant temperature rise above your hand temperature (97°).

Put your hand in the airflow of the condenser (outdoor unit) fan, it should be not too hot and not too cool (normally a 30° temperature rise above ambient). Too hot is a dirty coil (even if it looks clean). Too cool has to do with refrigerant issues which you should have detected at the refrigerant lines.

If you have an electric or heat pump unit you can test the electric heaters by turning them on (emergency heat switch), and observing the increase in speed at the electric meter.

Heat pump in the heating mode: feel the suction refrigerant line (the big one), the warmer the outdoor air temperature, the hotter the line should feel (above 32°F ambient).

Observe any signs of oil leaks or staining. Listen for any unusual sounds or vibrations.

In five minutes, your done!

There obviously will be times when you cannot be comfortable with performing all of these procedures but at least you gave it a try.