Why do I have oily film on windows no leaks anywhere and when I turn on max ac it blows warm air. Do I have air pocket, bad thermostat,or is it heater core
Sounds like a Freon Leak (freon has compressor oil mixed with it) or a coolant lead in the heater core. If it's a freon leak than it won't be long before the compressor fails to come on due to the freon pressure switch sensing low freon
Tom is right. Freon leaks come quick, and you would have likely seem the cloud. My bet....is a seep in the heater core, and as it warms and turns to steam it vaporizes on the windshield. Betting you soon find the right front carpet wet,,,or a drip behind the right front tire on the ground.
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