Questions and Answers

Toyota Carina A/C Problem? Q. Dear Vincent, I have a 1993 Toyota Carina 2.0 liter 4 cylinder M/T. I have problem with the A/C. The A/C lever temperature control is not function and it seems the compressor is working normal. They cut off itself when cold temperature reached, but in my opinion, it's only compressor cut off based on pressure change and not by temperature control. What should I do?? Regards, Dewanto

A. Before I can attempt to advise you on how to repair a problem, we need to know, first, if there is a problem. To this end we will need to do a Performance Test. This is how to perform the test:

Fig. 8 A/C Performance Chart

Performance Test

NOTE: R-134a systems require the use of special service equipment designed specifically for R-134a systems. R-12 servicing equipment cannot be used on R-134a systems.

1. Connect gauge manifold following manufacturer's instructions. Insert thermometer in the center vent outlet, then determine relative humidity and ambient air temperature by using portable weather station or calling your local weather station.
2. Ensure vehicle is not in direct sunlight, then open hood and front doors. Place temperature control at MAX COOL, press VENT and RECIRCULATE buttons, then switch fan to MAX position.
3. Start engine and operate at 1500 RPM for ten minutes with no driver or passengers in vehicle, then check delivery temperature from thermometer in dash vent and high and low system pressure from A/C gauges.
4. Using appropriate chart, Fig. 8, mark delivery temperature along vertical line, then intake temperature (ambient air temperature) along bottom line.
   
   Fig. 8 A/C Performance Chart

5. Draw line straight up from air temperature to humidity, then mark a point one line above and one line below humidity level (10% above and 10% below humidity level).
6. From each point, draw horizontal line across to delivery temperature. Delivery temperature should fall between the two lines.
7. Complete low and high side pressure tests in same way. Any measurement outside lines may indicate need for further inspection.

Once we have this test results we can determine our next course of action.