1970 L46 with AC Heater vacuum control troubleshooting

[William H.]

I have a 1970 L46 with AC and have a slow leak in the AC/Heater vacuum control system. I am assuming the entire system should hold vacuum or else the vacuum tank would bleed out completely. Since I may not be able to get to the problem source, has anyone installed a check valve to remedy? Thanks for your suggestions.

Bill

[Terry M.]

Re: 1970 L46 with AC Heater vacuum control troubleshooting

I have a 1970 L46 with AC and have a slow leak in the AC/Heater vacuum control system. I am assuming the entire system should hold vacuum or else the vacuum tank would bleed out completely. Since I may not be able to get to the problem source, has anyone installed a check valve to remedy? Thanks for your suggestions.

Bill

Years ago I was told, on the QT, one of our members installed a solenoid in the heater control circuit. This solenoid (it was a FORD product, of all things) was installed under the center console in the area of the heater controls. When the ignition was on the vacuum was open; with ignition off the vacuum was closed. The idea was to minimize leaks through the heater controls so the car could pass PV.

[William H.]

Re: 1970 L46 with AC Heater vacuum control troubleshooting

If a C3 sits for a few days or longer, will it hold vacuum in the tank or eventually bleed out?

[Terry M.]

Re: 1970 L46 with AC Heater vacuum control troubleshooting

If a C3 sits for a few days or longer, will it hold vacuum in the tank or eventually bleed out?

The vacuum will eventually bleed out. Most of us would be ecstatic if the system held vacuum over night. If my memory is right the PV standard is 3 to 5 minutes.