Performance Test
1. Install manifold gauge set.a. Close the HI and LO hand valves.
b. Connect the red charging hose to the discharge service valve of the compressor.
c. Connect the blue charging hose to the suction service valve of the compressor.
2. Run engine and operate air conditioner.
a. Run the engine at 2,000 rpm.
b. Set the blower switch at HI, temperature level at COOL, and air flow control level up.
c. Keep all windows and doors open.
3. Position thermometers.
a. Place a dry bulb thermometer in the cool air outlet.
b. Place a psychrometer close to the inlet of the cooling unit.
4. Wait until air conditioning system stabilizes.
a. Check that reading on high pressure gauge is 1373 - 1520 kPa (199 - 220 psi).
If the reading is too high, pour water on the condenser. If the reading is too low, cover the front of the condenser.
b. Check that reading on dry bulb thermometer at the air inlet is 25 - 35°C (77 - 95°F).
5. Check performance of air conditioning system
a. Calculate the relative humidity from the psychrometric chart by comparing the wet and dry bulb readings of the psychrometer at the air inlet.
b. Measure the dry bulb temperature at the cool air outlet, and calculate the difference between the inlet dry bulb and outlet dry bulb temperatures.
How to read the graph:
After measuring the temperatures of wet- and dry.bulb thermometers at the evaporator air inlet, relative humidity (%) can be obtained.
Example: Supposing dry and wet bulb temperatures at evaporator air inlet are 25°C and 19.5°C respectively, the point of intersection of the dotted lines in the graph is 60%.
c. Check that the crossing point of the relative humidity and temperature difference is between the two hatched lines.
How to get relative humidity: Measure temperatures of dry and wet bulb thermometers at air inlet (evaporator inlet), and bring them into mutual relation on the chart to find the intersection which is relative humidity.
For example, if dry-bulb temperature is 90°F, and wet-bulb temperature is 78°F, the relative humidity is 60%.
If the crossing point is within the two lines, the cooling performance is satisfactory.