Why does our porta potty smell like ammonia in the heat?

The ammonia smell is caused by heat accelerating the breakdown of urea in urine. At 110 degrees, the bacteria in the waste become more active and convert urea to ammonia gas much faster than the [deodorizer] can suppress it. The blue liquid you see is still present, but its odor-control capacity is overwhelmed by the rapid chemical reaction in the extreme heat.

It is likely your rental company is using a [formaldehyde-free deodorizer], which is now standard because many wastewater treatment plants restrict formaldehyde. These formulas are effective under normal conditions but can struggle in prolonged, intense heat. Your weekly [service visit] is the industry norm, but Phoenix heat is not normal; it requires a different approach.

To address this with the driver, frame it as a site-specific issue, not a complaint. When he arrives, you could say, 'The heat here is brutal on the units by the end of the week. Is there a stronger summer-grade chemical you can use, or would more frequent service help control the ammonia smell?' This focuses on the environmental challenge and invites a solution. The rental company may recommend a mid-week pump-out or a different chemical blend for high-temperature sites.