So I just installed a new vac pump on our06  Beaver, Monterey . My previous thread (a couple of weeks ago) was asking what was wrong in that I only had defrosters working. Most everyone's response was "BAD PUMP". Yep it was. Found one in Grand Rapids, Michigan. Thanks all !!! Now ... next question: with the ignition on and the dash fan off as well as the vent postion knob should the pump be cycling on and off? Or be totally off? Or running all the time? Mine cycles on and off ... on 10 seconds off 1 - 2 seconds. Not having any experience I have no clue which is correct. Seems like cycling will wear the pump off super quick. How bout it experts? Any input? Once again appreciate this web to the MAX. Thanks in advance.

The first thing that comes to mind is, why is the pump cycling. The most probable reason is that the pump turns off when a preset vacuum level is achieved and turns on when the vacuum level falls off. If you remove the vacuum hose from the pump and plug the port (hold your finger over it), and the cycling stops, you have a vacuum leak or no accumulator tank. If it still cycles, the power is being cycled or the pump has an internal circuit to cause it to cycle.

If you have an accumulator tank and the system operates properly (air comes out of the right vents), it would be easier to just rewire the pump to run only when the AC is turned on if you have a slight vacuum leak and can not easily find it.

Gerald

Congratulations on the  fix of the basic problem. When we replaced ours it would only cycle when we first started or changed settings IE AC to Heat. We do have an accumulator tank. The leak can be as easy as one of the vacuum hoses not being fully seated. Ours started cycling and I pulled wet and reseated the hoses and it solved the problem. We have an access panel on the front above the generator which makes it a lot easier to check.