Q: What is the importance of proper operation of the compressor clutch in the air conditioning system on Nissan Quest?A: Proper operation of the A/C clutch is essential to the function of the air conditioning system. If your system doesn't seem to get cold, first check the clutch operation. With the engine warmed up, set the air conditioning temperature selector on the coldest setting and the fan on high. Open the doors to make sure the air conditioning system doesn't cycle off as soon as it cools the passenger compartment down. Have an assistant switch the air conditioning On while you observe the front of the compressor. The clutch will make an audible click and the center of the clutch should rotate. If it doesn't, shut the engine off and disconnect the A/C system pressure switch. Bridge the terminals of the connector with a jumper wire and turn the air conditioning On again. If it works now, the system pressure is too high or too low. Have your system tested by a dealer service department or air conditioning shop. If the clutch still didn't operate, check the appropriate fuses. Inspect the number 13 and 29 fuses in the interior fuse panel. Remove the A/C clutch relay from the engine compartment relay panel and test it. With the relay out and the ignition On, check for battery power at two of the relay terminals. There should be battery power with the key On, at the terminals for the relay control and power circuits. Using a jumper wire, connect the terminals in the relay box from the relay power circuit to the terminal that leads to the A/C clutch. Listen for the clutch to click as you make the connection. If the clutch doesn't respond, disconnect the clutch connector at the compressor and check for battery voltage at the A/C clutch connector. Check for continuity to ground on the black wire terminal of the A/C clutch connector. If power and ground are available and the clutch doesn't operate when connected, the A/C clutch is defective. If the A/C clutch, relay, and related circuits are good and the system is fully charged with refrigerant and the compressor does not operate under normal conditions, have the PCM and related circuits checked by a dealer service department or other properly equipped repair facility.