Dash air vent parts

Furnace, air conditioning, thermostats, distribution.
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Svaughan
Posts: 2
Joined: Fri Sep 11, 2020 3:45 pm

Dash air vent parts

Post by Svaughan »

1999 safari Sahara 3126b, the dash air distribution doesn’t change where the air is coming out of - default defrost. I have found the vacuum pump behind the dash and the softball sized reserve unit. When I apply 12v (hotwire it) to the vacuum pump it runs, and i can see the vacuum actuator move when i change the control at the ac control and the air then changes to the correct outputs. There is, what appears to be a vacuum limit switch (copper colored unit) right next to the vacuum pump and has the electrical connector and vacuum line to it. The pump appears to work fine when but I don’t think the limit switch is working.
I have attached a picture of the pump, switch and reserve.
A: is there a way to test the limit switch? Is it worth the work?
B; does anyone know the part # for the limit switch?
C: is the limit switch really my problem?

Thank you
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Vacpumpandswitch.jpg
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Stevieray
1999 Safari Sahara 3126B

stuplich@ymail.com
Posts: 1047
Joined: Mon Oct 28, 2019 8:51 am

Re: Dash air vent parts

Post by stuplich@ymail.com »

Stevieray
This replacement vacuum pump has a built in switch:

Dorman number 904-214: https://tinyurl.com/uvmkrf9t
Mel
'96 Sahara 3530, mine since '01
250 hp 3126 Cat, MD3060 Allison

Svaughan
Posts: 2
Joined: Fri Sep 11, 2020 3:45 pm

Re: Dash air vent parts

Post by Svaughan »

Excellent, thank you
Stevieray
1999 Safari Sahara 3126B

TDJohn
Posts: 267
Joined: Sun Oct 27, 2019 11:34 pm

Re: Dash air vent parts

Post by TDJohn »

Svaughan wrote:
Mon May 17, 2021 7:46 pm
1999 safari Sahara 3126b, the dash air distribution doesn’t change where the air is coming out of - default defrost. I have found the vacuum pump behind the dash and the softball sized reserve unit. When I apply 12v (hotwire it) to the vacuum pump it runs, and i can see the vacuum actuator move when i change the control at the ac control and the air then changes to the correct outputs. There is, what appears to be a vacuum limit switch (copper colored unit) right next to the vacuum pump and has the electrical connector and vacuum line to it. The pump appears to work fine when but I don’t think the limit switch is working.
I have attached a picture of the pump, switch and reserve.
A: is there a way to test the limit switch? Is it worth the work?
B; does anyone know the part # for the limit switch?
C: is the limit switch really my problem?

Thank you
The switch can be tested by unplugging the vacuum line from the ball and plugging it. The switch should run for a very short moment and shut off. Often times the reason the pump does not shut off is because there is a vacuum leak somewhere in the system and the small pump does not have the volume to keep up and build enough vacuum to shut off. This situation often leads to the pump burning up, as it is not designed for 100% duty cycle.
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.

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