Operation CHARM: Car repair manuals for everyone.
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Performance Test

1. Install manifold gauge set.
2. Run engine and operate air conditioner.
a. Run engine at 2000rpm.
b. Set blower switch at HI, A/C switch ON, temperature control at COOL, and air flow control at vent.
c. Keep all windows and doors open.
3. Position thermometers.
a. Place a dry bulb thermometer in the cool air inlet.
b. Place a psychrometer close to the inlet of the cooling unit.
4. Wait until air conditioning system stabilizes.
a. Check that the reading on the high pressure gauge is 1,373 - 1,520 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 the reading on the dry-bulb thermometer at the air inlet is 25 - 35°C (77 - 95°F).

Relative humidity graph:





5. Check performance of air conditioning system.
a. Calculate the relative humidity from the psychrometric graph 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 inlet, and calculate the difference between the inlet dry-bulb and outlet dry-bulb temperatures.

System performance graph:





c. Check that the difference of the relative humidity and temperature difference is between the two hatched lines.

If the intersection is within the two lines, cooling performance is satisfactory.