When faced with a "no cooling" complaint, what method can a technician use to pressurize the system?

When a technician is faced with a "no cooling" complaint, it is often essential to pressurize the system for diagnostic purposes. Using an inert gas, like nitrogen, is a safe and effective method for pressurizing the system. Inert gases do not react chemically with the system components and help avoid complications that could arise from using refrigerants.

Using an inert gas allows technicians to identify leaks without introducing refrigerants that could deplete the ozone layer or contribute to global warming. Additionally, it enables the technician to safely test the system at pressures above the normal operating range without risking damage to the components. This method is especially important in HVAC systems where the presence of refrigerant oils and other materials could react adversely if subjected to high pressure with certain other gases.

The other options, including using R22 refrigerant or a high-pressure refrigerant, could cause issues related to system integrity, environmental regulations, or safety. R22, in particular, is an ozone-depleting substance, and using it for pressurization without intention to recharge the system would be against environmental regulations. Therefore, resorting to an inert gas is the correct and responsible choice for safely diagnosing a system with cooling issues.