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Old 06-25-2022, 05:54 PM   #1
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Does anyone know what this part is?

We have a 2005 Safari Gazelle 40' diesel pusher. The pictures show a part that is located above the slide out Generator compartment on the backside of the coach dashboard. Was wondering if anybody recognizes what it might be?
Seems to be making a humming noise and trying to find a place that works on RV's in our area is no easy task. Would appreciate any info if you know what it is.
Thank you
Linda F.
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Old 06-25-2022, 05:59 PM   #2
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Vacuum pump.
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Old 06-25-2022, 06:02 PM   #3
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My bet is itís a vacuum pump.
Looks like vacuum hoses connected to the top and side?
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Old 06-25-2022, 06:18 PM   #4
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Most heater controls operate on vacuum and with diesels not having a throttle plate, plus the engine being far from the heater,, they install small pumps to create the vacuum.
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Old 06-26-2022, 09:24 AM   #5
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Welcome to iRV2.

The vacuum pump should stop building vacuum , in the system after 30/45 sec. then only cycle again , after dash HVAC system is used to change modes .

If your pump is running continually , you're probably having trouble with dash mode controls ( slow mode changes) and you'll have to go through the system investigating for leaks .

The round plastic ball , ( left side , first photo) is a vacuum reservoir , and the first place the lines from the pump go, after that the lines run through the fire wall to the HVAC control head .

Evans , is one supplier of dash HVAC systems for motor homes, that use vacuum controls , here's a diagram of their vacuum system .
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Old 06-26-2022, 09:43 AM   #6
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Dried out cracked or split lines are usual suspect. Old vacuum balls often had cone shaped barbs ,those would often split the hoses at connections. Remove the line is it making vacuum. Plug the line ,I don't know if there is a vacuum switch that only runs pump when vacuum is too low. So it may turn off when vacuum makes switch. I don't think those pumps are really continuous duty. If running all the time driving it will probably die early.
For those that don't have a motor driven pump. Many have vacuum inductor/inducer/venturi mostly called vacuum generator that use air from compressor to produce vacuum as well. They are just rectangular cube shaped ,no motor has DOT air line to it. There's also 12v wires to it but It's solenoid/switched portion . Vacuum generators are not nearly as efficient a pump but as long there are no major leaks the MH compressor has plenty of air to go around.
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Old 06-26-2022, 10:26 PM   #7
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Originally Posted by Grtdnm View Post
Seems to be making a humming noise
Linda F.
You might want to remove both of those wire connectors, clean contacts with some 180/220 grit sand paper or 0000 steel wool, apply a dab of dielectric grease and reconnect. Bad or corroded contacts may be producing low voltage and causing humming.
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Old 06-28-2022, 09:58 PM   #8
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Thank you so much for the detailed information, gives us a few things to check out. Appreciate it
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