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Mysterious freon leak in 2007 Honda Civic

The freon keeps mysteriously leaking from my car. I have had the car checked 3 times from two different shops. One was a local place that I know is very honest, the other was the Honda dealer. Both put dye in and ran a check for leaks and found nothing. After the freon is replaced the a/c works for 2-4 weeks then stops and blows hot air. Any ideas on what could be happening?

You have used two different shops. Was either one a Radiator-AC shop? Most of the time it is not hard to find, but on occasion it takes someone with experience and the right tools.

Take the vehicle back so they can look for traces of dye. The dye usually show right after it is put into the system, two weeks if a normal amount of time to recheck for dye on the system components.

Sometimes when using only a dye they can make a mistake and overlook the schrader valve they used to inject it. That is, when they see dye around the valve it’s easy to assume it got there when they originally injected the dye. A sniffer or perhaps a sound detector could come in handy for this.

Thanks I will have them check the Schrader valve. Neither of the shops were radiator-ac shop, I don’t even know how to find one of those. I did take the car back after two weeks and still no leak was found. Thanks for the suggestions

Is they can’t find the dye on any of the external parts, it usually points to a bad evaporator, or expansion valve which is hidden in the dash.