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Vacuum Pump Connection

txhughes1 on Sun March 16, 2008 11:28 PM User is offline

Year: 1993
Make: GMC
Model: 1500
Engine Size: 5.7
Refrigerant Type: R-12
Ambient Temp: 60
Pressure Low: 0
Pressure High: 0
Country of Origin: United States

I'm preparing to replace the compressor on my truck. I did similar job on another vehicle about two years ago so I have most of the tools I will need. I got my vacuum pump and gauges out to dust off and test. I can't figure out how to connect the gauges to the vacuum pump. The yellow hose from the gauges has a valve at the end that connects to the pump. The connection on the pump does not depress the valve stem so no vacuum is pulled. How do I connect hose from gauges to the pump?

Vacuum pump is a Mastercool Economy 1.5 CFM Single Stage from ackits.com. Gauge set is Mastercool R134a Professional from local parts store.

I hope that's enough info for someone to help.

Cussboy on Mon March 17, 2008 9:42 AM User is offline

Gauge set, assuming the original hose colors are correct:

Close all gauge valves. Low side (blue hose) to low side of GMC. High side (red) to high side of GMC; you'll need an adapter fitting for the smaller high side fitting - there are two kinds (I have both), one for GM and some imports, other for Ford and my old Mazda truck, and they look pretty similar. Connect vacuum hose from middle of gauge set to vacuum pump. Open vlaves, turn on vacuum pump. After pulling good vacuum 1/2 to one hout, shut off valves, check vacuum for 15 minutes to assess whether there is leakage. If OK, attach R-12 source to yellow hose, bleed a tiny amount of refrigerant out of the yellow hose, then open up the Low Side valve, and the vacuum should draw in enough refrigerant where you can then start the engine and use the compressor to pull in the remainder - Keep the high side valve closed. By this time you can assess the refrigerant pressures; this should be done with the valves closed so no refrigerant is actually entering while you take your reading.

TRB on Mon March 17, 2008 5:19 PM User is offlineView users profile

Did you even try and pull a vacuum before thinking it would not work?

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Contact: ACKits.com

Chick on Mon March 17, 2008 5:43 PM User is offlineView users profile

If you have a 93 Gm you will "most likely" need the 91 to 93 GM high side adaptor because the shrader valve is recessed. I have seen some that were not, but most I see are, easy to check, if the shrader valve is not visable, you need that adaptor..Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Chick on Mon March 17, 2008 5:45 PM User is offlineView users profile

Opps, it's the number "J" part number 90339 and Tim, (ackits.com) either has them in stock, or can get it for you.

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

TRB on Mon March 17, 2008 5:58 PM User is offlineView users profile

I just used a hose R134a hose from our Mastercool Professional gauge sets. Attached the end with depressor to a Mastercool pump without depressor and vacuum was pulled.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

txhughes1 on Mon March 17, 2008 10:47 PM User is offline

Thanks for all the quick replies. I was able to pull a vacuum this evening. It was just extreme user error after not using the equipment for two years. I probably should have just let it go last night and tried again this evening. Anyway, thanks for the replies.

Edited: Mon March 17, 2008 at 10:51 PM by txhughes1

TRB on Mon March 17, 2008 11:59 PM User is offlineView users profile

Forum is here to bounce questions off us. So feel free to post up anytime!

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

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