Coolant Vacuum Switch Cold Closed (CVSCC) Valve Test

Coolant Vacuum Switch Cold Closed (CVSCC):

ON VEHICLE TEST

1. Check vacuum hoses for correct routing and valve installation. The bottom port is where the source vacuum connects, and the top port connects to the air switch/relief valve.
2. Check engine coolant level.
3. With the valve installed, disconnect molded connector from valve and connect a 1/8" vacuum hose to bottom port of valve.
4. With the radiator top tank warm, about 75°F, blow through the hose.
5. If it is not possible to blow through the hose, replace the valve.
6. Start engine and allow to warm to normal operating temperature. Connect a hand operated vacuum pump to bottom port of valve and apply 10 inches Hg vacuum to the valve. If vacuum drops more than 1 inch in 15 seconds, replace the valve.

BENCH TEST

1. Remove the valve from the vehicle and place the threads in a bowl of ice water that is less than 40°F.
2. Attach a hand-operated vacuum pump to the bottom nipple of the valve.
3. Apply at least 10 inches Hg of vacuum, and make sure that the signal does not drop more than 1 inch in one minute. If the switch cannot hold this vacuum for one minute, then the valve is defective and needs to be replaced.