Quote:
The instructions also say to bring the system down to 28 or 29" Hg with a recovery system before using the pump and to run it 10 min...
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| Harbor Freight electric vacuum pumps? https://slantsix.org/forum/viewtopic.php?t=33206 |
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| Author: | KBB_of_TMC [ Wed Jan 07, 2009 10:27 am ] |
| Post subject: | Harbor Freight electric vacuum pumps? |
Does anyone have any experience with the new Harbor Freight 1.2 cfm (98074-1VGA) or 2.5 cfm (98076-4VGA) electric vacuum pumps for evacuating a Mopar A/C system? Thx |
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| Author: | SlantSixDan [ Wed Jan 07, 2009 10:48 am ] |
| Post subject: | |
If you want to use it once or twice and then throw it away when it breaks, it might get the job done for you — that's the kind of low-quality Chinese dreck Harbor Freight sells; that's why their prices are low. If you're not interested in the hassles of poor quality, you can probably get much better bang for your buck by shopping for a used high-quality pump in good condition. They're really all over the place. A constant stream of them flows across eBay, and you can probably find them locally at used-tool places or perhaps on Craigslist. If you do buy anything electrically-operated from Harbor Freight, use it with great care and keep a close eye on it at all times when it's plugged in. The low-bid Chinese factories where HF source their stuff are also the source of most of the counterfeit UL (and other safety approval) labels. Remember the car fires caused by their fuses that didn't. |
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| Author: | emsvitil [ Wed Jan 07, 2009 4:46 pm ] |
| Post subject: | |
If you have an air compressor, get the venturi vacuum pump.... No moving parts to break..... |
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| Author: | Charrlie_S [ Wed Jan 07, 2009 7:18 pm ] |
| Post subject: | |
Quote: If you have an air compressor, get the venturi vacuum pump....
and not enough vacuum to bother with.
No moving parts to break..... |
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| Author: | KBB_of_TMC [ Thu Jan 08, 2009 9:39 am ] |
| Post subject: | |
Thanks for the advice; I'll certainly keep the fire hazard in mind. I had purchased a venture vacuum pump, but heard that they produce a rather poor final vacuum (0.5"Hg) (and I don't have a big enough air compressor). I only intend to use it a very few times, and HF advertises a very good final (25umHg) vacuum. I used to do a lot of high (<1E-6 torr) vacuum work years ago, and my experience with well used vacuum pumps has not been very good, as they were pretty cruddy inside and didn't produce nearly their rated vacuum (sometimes by a factor of 25X). My system probably has a fair amount of water vapor in it after so long and and I'd like to avoid any oil backstreaming - is there an inexpensive trap out you could recommend, or isn't it an issue in AC systems? Thanks Again. |
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| Author: | emsvitil [ Thu Jan 08, 2009 2:31 pm ] |
| Post subject: | |
According to my gauge set, I got down to 30" with a venturi vacuum. Ran it about an hour to make sure all the water got out. |
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| Author: | Charrlie_S [ Thu Jan 08, 2009 7:36 pm ] |
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I will not get into any arguments about this. I will post my thought's once for anyone to consider. A Venturi vacuum pump cannot, by its very nature, pull much more then 25 inches of vacuum. The amount of vacuum necessary to remove the moisture from a A/C system is more then 29 inches (depending on ambient temp.). The only way to acuratly measure more then 29 inches of vacuum, is with a micron gauge. Most every mechanical A/C vacuum/pressure gauge, will be off by 1 to 2 inches of vacuum, even a new quality gauge. |
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| Author: | Bren67Cuda904 [ Thu Jan 08, 2009 8:20 pm ] |
| Post subject: | |
Quote: I will not get into any arguments about this. I will post my thought's once for anyone to consider.
TrueDat
A Venturi vacuum pump cannot, by its very nature, pull much more then 25 inches of vacuum. The amount of vacuum necessary to remove the moisture from a A/C system is more then 29 inches (depending on ambient temp.). The only way to acuratly measure more then 29 inches of vacuum, is with a micron gauge. Most every mechanical A/C vacuum/pressure gauge, will be off by 1 to 2 inches of vacuum, even a new quality gauge. |
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| Author: | KBB_of_TMC [ Fri Jan 09, 2009 9:34 am ] |
| Post subject: | |
I decided I felt lucky and bought the HF 1.2 cfm pump for $70 on sale. It looks to have only single stage (so 25 um Hg may be optimistic, but I don't have anything to measure vacuum well anyway). It says it has a 1yr warranty, but the guy at HF told me it was only 90 days and wanted to sell me an extended warranty. The instructions also say to bring the system down to 28 or 29" Hg with a recovery system before using the pump and to run it 10 min... (they don't say what happens if you run it more than 10 min or start from atm). I'll give it a try in the spring; with a little luck it'll work well enough. |
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| Author: | SlantSixDan [ Fri Jan 09, 2009 10:42 am ] |
| Post subject: | |
Quote: The instructions also say to bring the system down to 28 or 29" Hg with a recovery system before using the pump and to run it 10 min...
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