First check is to see if pump comes on when car is warming up.
If not , the problem is more likely electrical.
If you have a vac gauge and are a DIYer, there is a simple test you can do to help diagnose the system:
At the air valve between the pump and the engine, there is a small vac line. Take it off the valve and check it for vac as car warms up [ pump only comes on for up to 110 sec. during warm-up].
If it has vac sometime during warm-up, it means the air valve has received the required sig from the ECU and also lets
you know that there is vac and power to the switch over valve [which let vac get to this line]from the engine. This test also tells you that the pump clutch also has power cuz the SOV and pump clutch are wired to the same feed from the ECU..

If no vac at this line , then you may have a broken vac line from the eng [ top,front] to the switch over valve, or no power to the SOV. Start looking..
[the SOV is located between the hose you have the vac gauge on and the eng vac line]

If you do have vac here and the pump is running, then you may have a bad/stuck air valve

A tech can find these as the system is not a complex as it sounds
I can send you a vac diagram that once looked at,the above info falls into place..
email me if needed