You can leave that Robinair pump running all night if you want; I have one just like it. Just make sure it is properly filled with new dry oil for the best pump performance. Cheers, Jim

neophyte question again:

"new dry oil" - you mean change the oil before each use? do I use the same oil that I run in my ac system? I use 134a so it would be the syntetic oil, right?

No, one uses mechanical vacuum pump oil; the new pump will come with a sealed bottle sufficient for the first fill. If the pump sits for more than a couple of weeks (here in dry New Mexico) or has done more than two A/C systems I change to new oil. It is easy to do on the pump you listed as it has a integral drain. The problem is the oil picks up water and that limits how low a vacuum the pump can achieve. The oil is relatively cheap and you can buy it from the places that sell the A/C servicing vacuum pumps.

OK, got it. Thanks guys. Need to buy spare oil and better gauges.

Replacement vacuum pump oil:

http://www.toolsource.com/ost/product.asp?sourceid=&dept%5Fid=500&pf%5Fid=59302& mscssid=8F36QS6G42EX9JSP0GWUUSWAMCUJ9DC7

[QUOTE]Originally posted by rusnak
Kuehl, thank you for the advice. 3 hours though? Won't my residential hobbyist type of pump overheat? What if it turns off to protect itself, do I try to shut the valves and then re-start the evacuation?

Well if you don't trust your pump then don't trust your pump. Heck, if you are concerned about leaving it running then just invite the gals over for a few hands of gin, or glasses, or whatever and babysit the pump. My concern with pumps is more related to temperature and oil viscosity.
Leave a pump running outside in the sun on a warm day and you'll figure it out.

You can evacuate for less time if you wish, however our experience tells us 3 hours (running).

There are a few good brands out there, SPX RockinRobinair is one. And there is a lot of inexpensive "stuff" being imported from various countries that have yet to have to deal with customer returns. I purchased a Robin a few years ago over the counter from our local supply shop and it started getting noisy after 4 hours. They replaced it, no questions asked after I let them listen to on the speaker phone; swapped it out the same day, so I have no problem spending a few extra dollars for an item with a warranty. I would not suggest Walmart, at least not yet.


Also, I thought I'd clarify for those running R-12 that the pressures for 134a are significantly higher, which is why most people upgrade their pump to an ND, Seiko, or other rotary pump when they switch to 134a.

Yes and no. Pressures, we already know about, are higher with a stock system, especially if you overcharge using small cans rather than using P&T's. Most of us replace the old Yorks because either:
A) they vibrate too much
B) the service valves leak
C) they weigh too much, take up too much room
D) not economical to rebuild
E) less efficient than new styles
F) attaching R134a charge port adapters to them is not fun any more.
G) should I stop here?

[QUOTE]Originally posted by kuehl

Quote:

Originally posted by rusnak Kuehl, thank you for the advice. 3 hours though? Won't my residential hobbyist type of pump overheat? What if it turns off to protect itself, do I try to shut the valves and then re-start the evacuation? Well if you don't trust your pump then don't trust your pump. Heck, if you are concerned about leaving it running then just invite the gals over for a few hands of gin, or glasses, or whatever and babysit the pump. My concern with pumps is more related to temperature and oil viscosity. Leave a pump running outside in the sun on a warm day and you'll figure it out. You can evacuate for less time if you wish, however our experience tells us 3 hours (running). There are a few good brands out there, SPX RockinRobinair is one. And there is a lot of inexpensive "stuff" being imported from various countries that have yet to have to deal with customer returns. I purchased a Robin a few years ago over the counter from our local supply shop and it started getting noisy after 4 hours. They replaced it, no questions asked after I let them listen to on the speaker phone; swapped it out the same day, so I have no problem spending a few extra dollars for an item with a warranty. I would not suggest Walmart, at least not yet. Also, I thought I'd clarify for those running R-12 that the pressures for 134a are significantly higher, which is why most people upgrade their pump to an ND, Seiko, or other rotary pump when they switch to 134a. Yes and no. Pressures, we already know about, are higher with a stock system, especially if you overcharge using small cans rather than using P&T's. Most of us replace the old Yorks because either: A) they vibrate too much B) the service valves leak C) they weigh too much, take up too much room D) not economical to rebuild E) less efficient than new styles F) attaching R134a charge port adapters to them is not fun any more. G) should I stop here?

You must be a joy to deal with as a vendor. Or as a customer. I wouldn't really know.

I really don't see anything wrong with the OPINIONS he stated.

If that response wasn't intended to be sarcastic...... never mind

Rus, may have a point. However I think if everyone simply posted answers on the forum, such as "Yes" or "No" it would get boring. On the otherhand Pelican would save on storage space and bandwidth.