My AC Guy Says My System Is “Low on Freon” but Can’t Find a Leak
Your AC guy says your system is low on refrigerant, but they can’t find a leak.
Can that happen?
Absolutely.
Finding that a system is undercharged and finding where the refrigerant escaped are two different things.
First: Is It Actually Low?
Before hunting for a leak, we’d want to establish that the system really is undercharged.
That means looking at the whole refrigeration picture—not one pressure on a gauge.
Depending on the system, we’re looking at things like:
- superheat
- subcooling
- suction and liquid pressures
- indoor and outdoor temperatures
- airflow
- manufacturer charging specifications
If those measurements support an undercharge, then we have another question:
Where did it go?
Why Can’t They Find the Leak?
Because refrigerant leaks can be jerks.
Some are enormous.
Pressurize the system and the leak detector practically finds it from the driveway.
Others are extremely small.
They may be hidden:
Inside an evaporator coil.
Inside a condenser coil.
Underground.
Inside a wall.
In a building chase.
At a fitting that’s difficult to access.
And some leaks occur slowly enough that finding the exact location can take considerably more work.
So:
“I couldn’t find the leak today.”
doesn’t automatically mean your technician doesn’t know what they’re doing.
Sometimes the leak genuinely isn’t obvious.
What Happens Next?
That depends on how significant the refrigerant loss is and what we’ve already tested.
We may need to:
- perform a more extensive electronic leak search
- use bubble solution at suspected areas
- pressure test with nitrogen
- isolate sections of the refrigeration system
- monitor pressure over time
We’ve had systems where we separately isolated the condenser, evaporator and refrigerant lines before finally proving which section was leaking.
Sometimes troubleshooting takes longer than we’d like.
Unfortunately, refrigerant leaks don’t care about our schedule.
Could It Have Been Undercharged From the Beginning?
Yes.
That’s another possibility.
If the system has never been properly charged, somebody may discover an undercharge without there necessarily being an active leak.
That’s why history matters.
But if the system previously had the correct charge and now it’s significantly low?
That refrigerant went somewhere.
The Klein Answer
Your technician can legitimately determine that an AC appears undercharged without immediately finding the leak.
That doesn’t make the refrigerant loss normal.
It means the diagnosis isn’t finished yet.
If it’s a significant or recurring loss, keep looking.
Because sometimes the leak is sitting right in front of us.
And sometimes it’s seven stories down a building shaft on a Monday afternoon.
Ask us how we know.