Hey all! I recently came across a simple but effective way of looking at A/C refrigerant flow, I shared this on LinkedIn and figured I'd share it here also. I typically struggle with trying to remember the state of refrigerant as it passes through the system. When is it a liquid or a gas? When is it high-pressure or low-pressure? What about temperature??? I have found that the simplest method to remember is by drawing two perpendicular lines on a piece of paper to make a cross or 'plus' symbol. At the top of the vertical line draw a compressor. At the bottom of the vertical line draw a TXV or Orifice Tube (restriction device). At the far left of the horizontal line draw a condenser, and at the far right of the horizontal line draw an evaporator. The horizontal line represents the state of the refrigerant—the refrigerant above this line is in a gas state, refrigerant below is a liquid. The vertical line represents the pressure of the refrigerant—the refrigerant to the left of this line is high pressure, the refrigerant to the right is low pressure. To my brain, this is the simplest way to remember the state of refrigerant as it passes through the A/C system. The compressor takes low-pressure gas and compresses it into a high-pressure gas. As it goes through the condenser, the refrigerant loses heat and condenses into a high-pressure liquid. The restriction device (TXV or Orifice Tube) causes the pressure of the refrigerant to drop so that it enters the evaporator as a low-pressure liquid. As it passes through the evaporator, the refrigerant absorbs heat from the cabin and evaporates from a liquid to a gas. This low-pressure gas then flows back into the compressor, and the cycle starts all over again. Hope you found this as helpful as I did!