Originally Posted by George

BTW, there is no single "magic temperature" for the AC to be "within spec" The repair manual test specifies the following:

(Repair Manual, page 55-4)

1. Cowl Inlet temperature (that's OAT) must be between 25C and 30C (That's 77F to 86F)

2. The technician must determine relative humidity by using a wet/dry bulb thermometer at the air inlet and consulting a psychrometric chart. Relative humidity must be between 30% and 70%

3. The vehicle must be stopped, in the shade, the door fully open, the AC switch on, engine at 2000RPM, inlet switch to outside air, outlet switch to face outlets only, temperature on max cold, blower on high, and high side pressure gauge at 1.5MPa.

4. The correct difference between the inlet and outlet temperatures is found by consulting another chart in the manual:
At 30% relative humidity, the difference between inlet and outlet temperature should be 19.5C to 25C. (35.1-45F)
At 40% relative humidity, the difference between inlet and outlet temperature should be 18C to 22,5C. (32.4-40.5F)-
At 50% relative humidity, the difference between inlet and outlet temperature should be 16C to 21.5C. (28.8-38.7F)
At 60% relative humidity, the difference between inlet and outlet temperature should be 14C to 19.5C. (25.2-35.1F)
At 70% relative humidity, the difference between inlet and outlet temperature should be 12C to 18C. (21.6-32.4F)


So, let's say that it's 80 degrees outside and the humidity is 40% The temperature difference is 32.4-40.5F, so the AC is OK if the outlet temperature is somewhere between 39.5F and 47.6F.

As you can see, the system cannot even be tested unless the outside temperature is between 77F and 86F. One also wonders if there are any Toyota technicians outside of Japan who can actually perform the psychrometric determination of relative humidity _and_ who have the equipment and motivation to do so.