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The AC in my 99' Yukon quit working last Jan. Pep Boys recharged it and put a dye in to find leaks. It worked fine all year until last month when I would turn the ac off because the temp dropped outside. In Florida it gets cold one day and it is 85 the next. After cycling the systen on and off a few times it quit working. The pressure was low and I bought a recharge kit. The air was cold for less than one day. Could there be a leak that is triggered when ac button is turned off and on?
 

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Cycling the switch should have no effect on a leak. Every time you turn the engine off, the system equalizes between the high and low sides. It probably just got low enough again for the low pressure switch to shut it down. You can sometimes find the leak by looking at the lines and joints and find where the greasy spot is (if you keep your engine otherwise clean). The oil in the refrigerant grabs dust and leaves a greasy spot at the leak site.
 

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Cycling the switch should have no effect on a leak. Every time you turn the engine off, the system equalizes between the high and low sides. It probably just got low enough again for the low pressure switch to shut it down. You can sometimes find the leak by looking at the lines and joints and find where the greasy spot is (if you keep your engine otherwise clean). The oil in the refrigerant grabs dust and leaves a greasy spot at the leak site.
Good info.
 

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If they put dye in the AC system to look for leaks, you can pull out a black light and start shining it in the engine bay. The dye should be UV reactive, so it should show up with the black light. Hope this helps.
 
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