What is a key disadvantage of using R-407C compared to R-22?

The correct answer highlights an important characteristic regarding the use of R-407C compared to R-22, specifically concerning temperature glide.

R-407C exhibits a larger temperature glide, which refers to the difference between the evaporating and condensing temperatures. This larger glide can result in performance issues in certain applications, especially those that rely on precise temperature control, as it may lead to less efficient heat transfer and more adjustments needed for optimal system performance. This behavior can complicate system design and operation, particularly in systems originally designed for the fixed temperature characteristics of R-22.

In contrast, R-22 has a lower temperature glide, meaning it can operate more consistently under varying load conditions, which is preferred for many air conditioning applications. The implications of temperature glide become particularly relevant when retrofitting existing systems or when designing systems intended to operate under specific conditions. Understanding these characteristics is crucial for technicians and engineers when selecting refrigerants for specific applications.