Required Tools and Preparation
📌 Essential tools include a vacuum pump (check oil level between min/max marks), a pressure gauge manifold, an 11mm flat wrench to decompress the service valve stem, a refrigeration wrench/adjustable wrench, and a flathead screwdriver for zero adjustment.
⚙️ The manifold features a blue low-pressure (BP) gauge and a red high-pressure (HP) gauge; zeroing is crucial due to vibration sensitivity.
🧤 Technicians must wear gloves as the refrigerant side is very hot (HP) or very cold (BP), posing a burn risk, and must use safety glasses.

Procedure for Manometer Installation
🔌 Connect the HP flexible hose (red) to the HP service valve on the liquid receiver, ensuring the service valve stem is in the rear/closed position before opening the pressure port.
🌬️ Connect the BP flexible hose (blue) to the BP service valve, confirming its service valve is also in the rear/closed position before opening its pressure port.
💧 Use the yellow flexible hose connected to the vacuum pump to evacuate the air/moisture from the connected HP and BP hoses; stop vacuuming when both HP and BP gauges reach -1 bar.

Releasing Refrigerant and Post-Installation Checks
🔧 After evacuating the hoses, close the shut-off valve on the yellow hose *before* turning off the vacuum pump, and then close the HP and BP valves on the manifold.
💨 To release refrigerant, first slightly unscrew the service valve stem (presta-stud) with the 11mm wrench, then use the ratchet wrench (clockwise) to open the service valve stem, checking for pressure rise on the BP side.
🛑 Repeat the stem release process for the HP side, ensuring the presta-stud is re-tightened afterward, signifying the end of the installation setup.

Procedure for Manometer Removal (After System Run)
🥶 Begin removal by closing the HP service valve and decompressing its stem, then close the liquid receiver valve to stop refrigerant flow to the evaporator.
💨 Open the BP shut-off valve on the manifold; the compressor will begin sucking the refrigerant out of the HP side and the flexible hoses.
📉 Continue forcing the BP stem open until the BP and HP gauges reach 0 bar, then return the BP service valve stem to the rear/closed position.

Key Points & Insights
➡️ Organize the workstation well, as there are many sequential manipulation steps required for safe hookup.
➡️ Always re-tighten the presta-studs immediately after opening or closing service valves to ensure seals are maintained.
➡️ Failure to close the HP and BP manifold valves after vacuuming can lead to HP liquid entering the compressor, which is very dangerous.
➡️ When removing hoses, use the compressor to suck the remaining refrigerant out of the hoses until the gauges read 0 bar before disconnecting completely.

📸 Video summarized with SummaryTube.com on Dec 04, 2025, 19:59 UTC