the pump itself works. i disconnected it and wired it to battery. it does not work when i set my heat on. this makes it cold in traffic. is that the only function of this pump or is it supposed to run any other time? the car has electronic heater and a/c controller.

 

I am not sure what you mean. are you talking about the heater box? all other systems work fine. when the car idles in traffic the heat drops off. it comes back immediately when the throttle is pressed. the flow of air inside the car and switching from cooling with a/c to heating, defrost-defog ect. work o.k. i thought that the secondary water pump was supposed to move water through the core at idle. checking around i found the info on the servo housing and will inspect it today.