The cooler weather is upon us.  For many of us that is reason to celebrate.  But, for many home buyers, there’s this awkward moment that arises in the inspection process in the fall and winter.  Here’s an example of how it often plays out.

Imagine it’s a lovely day.  Today’s high is going to be 72-degrees.  It’s absolutely perfect and everyone’s feeling the love of fall.  Then the inspector is going through the inspection review and gets to the A/C and furnace conversation.  At this point the inspector shares that they are not able to test the A/C because it was too cold last night.  This, understandably, creates some stress and anxiety for the seller because that’s a large ticket item and now we can’t test it.  Why can’t the inspector test the A/C on such a nice day?

Let’s start by explaining a little about how air conditioners work.  This won’t go too deep–stick with me. 

Air conditioners have a refrigerant in them to help it create cool air.  This refrigerant goes through the condensing unit as a gas and in the process it transfers the heat from the gas into the air through the coils. When an air compressor is working on a warm day you can feel the heat coming out above the fan on the outdoor compressor.  This process of the gas under pressure and transferring heat cools the gas down.  In the gas state, it can go through the system to create the cool air generating the cold air into your vents–usually between 52-57 degrees.

Here’s the reason the A/C can’t be tested when the temperature is below 60 degrees overnight.  In cold weather the refrigerant is no longer in a gas state.  It becomes a liquid.  When the A/C is run while the refrigerant is in this liquid state it can put strain on the system and then clog it.  Once the machine attempts to force the liquid into the system it can cause damage.

The general rule of thumb is that an A/C system should not be used when the outdoor temperature has been below 60 degrees in the past 24 hours.  The conversion from liquid back to gas needs enough heat and time.  It could be 72 degrees this afternoon, but the temperature from the previous night could still put the unit at risk of harm because the refrigerant has not become a gas yet.

There are some A/C professionals that may do more invasive inspections than a home inspector.  But, most A/C technicians simply have limitations to what they can do with a system in colder whether.

During this time of the year, agents will usually get a document from the seller that verifies the operation of the system when they last used it.  While we would love to be able to get more information on the system, there is simply not a viable way to do so in colder temperatures.