My rooftop A/C (have 1 since I'm 30 amps) has worked great and it still cools but when I start it there's a horrible smell. It doesn't smell like mildew it smells like chemicals coming in to the R/V. I've been full-time for 1.5 years and this just started. I can't use the A/C because I feel like I'm breathing in poison. Think it's just that the A/C needs a good cleaning up there?