Don't forget to cover up your heater vents with a screen mesh. If you don't, those pesky mud dobbers and wasps will clogg up the whole works. This also applies to most of your other vent openings that make dandy insect condos. If you're having trouble keeping your trailer cool, you might try adding window awnings, or at least tinting the windows. Inexpensive solar tinting for the inside of your RV can help keep it cooler in the summer. Easily attached, it can reduce the cool loss through the windows substantially. The more direct sunlight shining through the windows, the harder it'll be to keep cool. You can even draw the shades. Has your A/C been freezing up? No, it's probably NOT low on freon. Your filter is probably clogged up! If your condenser or evaporator can't breathe it will freeze. Don't just peg the thermostat to the lowest position and leave it there all the time. The A/C has to "cycle" on and off or it'll freeze up. If it does freeze, turn the thermostat back 'till the compressor shuts off but the fan keeps runnin'. That'll thaw it out.