I assume the blower motor is working. Check the vacuum supply line at the firewall, usually on the passenger side. Make sure there is vacuum there. If there is no vacuum there, follow the line back to see where the break is. If there is vacuum there, then move under the dash and look for broken or disconnected vacuum lines.
The parking brake release is also on this vacuum circuit. Does it release properly when the car is placed in gear? If not, concentrate there.
The parking brake release is also on this vacuum circuit. Does it release properly when the car is placed in gear? If not, concentrate there.