[KULTULZ]

IF the vacuum pump is not putting out ... ... all vacuum accessories will not operate properly at high demand throttle position(s). The power brakes (if equipped) will function as it has a vacuum reserve.

You have to check the condition of the hoses (and wiper vacuum motor) as to be able to hold a vacuum signal. That pump senses when manifold vacuum drops and only cuts in at that point (manifold vacuum is routed through the vacuum pump).

As for heat, you must ascertain a proper signal to the control valve. You then check function/coolant passage through that valve. You then confirm the temp control valve at the heater core is adjusted and functioning properly. Check heat at the pressure hose and the return hose. If hot on the supply and cool on the return, you have a blockage (valve - core -trapped air).

All is fully explained in the SHOP MANUAL.

The two-stage pump was an option on lower trim models.