A/C Vacuum 6.2 Diesel

[sonicbluezx3]

Long story short, my truck was originally a 4.3L V6 with no A/C. It currently has a 6.2L diesel and all of the plumbing and the heater box and controls have been added in order to have A/C. However, I need vacuum. There is a vacuum pump, but I'm not sure how to connect the vacuum from the pump to the controls. Help?

 

[sonicbluezx3]

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=CRB220016_0351819304 This is the vacuum pump I have. I assume that I need to just attach the vacuum line from inside the cab to the L shaped tube that has a cap. Is this correct? I'm going to need some sort of reducer I believe to connect it. Guessing that the vacuum pump is meant for more than just A/C controls (transmission, etc.)

 

[chengny]

Vacuum:

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Electrical;

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Vacuum pump function on diesels:

Since the air crossover and intake manifold in a diesel engine is unrestricted (unlike a gasoline engine which has throttle plates creating a venturi effect) there is no vacuum source. To provide vacuum, a vacuum pump is mounted in the location occupied by the distributor in a gasoline engine. This pump supplies vacuum for the EGR valve system, air conditioning servos, the cruise control servos, and the transmission vacuum modulator, where required.The pump is a diaphragm type pump which needs no maintenance. It is driven by a drive gear on its lower end which meshes with gear teeth on the end of the engine camshaft.

 

[sonicbluezx3]

Hmm, it shows a vacuum tank on there. Is that the little black circular box? I'll have to find one I guess if that's the case. Any idea where it is supposed to be located?

And thanks for the diagrams btw. Very helpful.

 

[chengny]

Hmm, it shows a vacuum tank on there. Is that the little black circular box? I'll have to find one I guess if that's the case. Any idea where it is supposed to be located?

And thanks for the diagrams btw. Very helpful.

No, no - that vacuum reservoir is specific to gasoline engines only - see the note for item #46.

You are correct in that the vacuum used to operate the HVAC in a diesel truck is provided by the vacuum pump.

I just posted that diagram in case you needed to look at the under dash hoses, sorry!

Connect the hose that would normally attach to the vac chamber to the vacuum pump. Just think of the vacuum chamber as the vac pump. And there wll be no connection to engine vacuum (because there is none).

 

[sonicbluezx3]

Oh I didn't realize that. Thanks for clearing that up.

Thanks for the diagram, it does help. I've got to figure out where the vacuum line that conencts to the pump is and pull it through the firewall and then get some sort of splitter for the vacuum pump since right now it's just got a large connector on it. I guess it normally has a tee with 3 or 4 different connections for transmission, etc.