I have reviewed the other pertinent posts concerning the AC blowing through only the defrost....

My system, with or without the AC will blow through the dash vents for about 2 minutes and then default to the defroster. So I am fairly convinced that my problem lies with the pump going out when the bearing in the pump warms up.

My question is...in order to finish troubleshooting the system (to determine if I don't have any other vacuum issues) is it possible to use a hand vacuum pump connected to the vacuum line (disconnected at the vacuum pump)? Is the system designed to hold a vacuum in this fashion?

In addition, is it possible to test the vacuum pump on the engine by connecting a vacuum gauge to the pump while the engine is running? If so, what might I expect for a reading?

Thanks for any help.

 

welcome to FTE.
short answer, yes to both.
disconnect the line from the vacuum pump, and put your hand pump on. draw 20 inches and let it sit. it should hold if all connections are good.
then try switching the heat/AC controls.

as for testing the vacuum pump, put a vacuum gauge directly to the pump and start the engine. you should see at least 20 inches. if not more. .

 

Thanks for the quick response. I will try to get on this during the weekend.

eodtek32