To charge refrigerant gas in a split AC unit, first ensure the system is off and locate the service valves on the outdoor unit. Connect a refrigerant gauge manifold to the low-pressure side, then attach the refrigerant canister to the high-pressure side. Open the service valves and allow refrigerant to flow into the system, monitoring the gauges to maintain the proper pressure levels. Once the desired charge is achieved, close the valves, disconnect the gauges, and run the system to check for proper operation.
Suction pressure
Pressure gauges. In a home or car AC there is small pipe and a large pipe going to the compressor unit outside or in the engine compartment. The large pipe should be cold and "sweating" ( dripping water).
replacement is cheap. unplug the fans with the ac on, or block the condenser. Have gauges connected to monitor the pressure. It should trip before it reaches 400
The high pressure side.
With AC pressure gauges and manifold assembly. This is best done by a professional.
A pressure switch a valve that shuts off the unit when the pressure is to low or to high
Low pressure for R 410 is 118 psi
The low pressure (vacuum) side.
To know when an air conditioning unit (non-window unit) needs to be charged (needs freon), it will not cool properly or you can test it with the appropriate gauges (see related link below).
unless you are quialfied to do this, call a repair man,the GAS in a/c units are under HIGH pressure, 350 lbs or more.and you have to have a set of gauges to set it right, theres a high side and a low side,
The pressure of an AC unit on a 90 degree day can vary depending on factors such as the specific unit, its operating conditions, and any potential issues with the system. Generally, the pressure in an AC unit would typically be higher on a hot day due to increased demand for cooling, but it would be best to consult with a professional HVAC technician for an accurate assessment.