Coolant Vacuum Switch Cold Open (CVSCO) Test

1. Check vacuum hoses for correct routing and installation.
2. With valve installed, disconnect molded connector from valve. Connect a 1/8 inch inside diameter hose to bottom port of valve.
3. With radiator top tank warm (no warmer than 75° F), blow through hose. If it is not possible to blow through hose, replace valve.
4. Operate engine until normal operating temperature is obtained.
5. Connect a suitable vacuum pump and gauge No. C-4207 or equivalent, to bottom port of valve. Apply 10 inches Hg vacuum to the valve. If vacuum level drops more than one inch in 15 seconds, replace valve.