) and in order to put R-134 refrigerant back into an empty system you need to get all the atmospheric moisture out of the lines or it will freeze in them. To do this you pull a vacuum of AT LEAST 29.22in/hg so the water will boil and get sucked out of the system as a vapor. Anything LESS than 29in/hg means the ambient temps have to be above 80F to get water to boil.So you need a vacuum pump. The Harbor Freight units are highly rated and so I look on the HF site.. one of the items was a venturi generated vacuum 'pump' (this is not the vacuum pump I was looking for):
http://www.harborfreight.com/air-vacuum ... 96677.html
So I read the reviews:
"I was able to get it down to -30 with cycle of the air compressor"
"Great easy to use and connect pulled vacuum down to 28" no problem" - this is actually correct, but you will NOT remove moisture from an AC system at 28in/hg
" BROUGHT THE VACUUM DOWN TO 30 FAST"
ad nauseum...
But the winner is:
" It reach -30 but I found a leak in the evaperator [sic]"
So evidently this HF venturi powered vacuum pump can break the laws of physics... it can pull a PERFECT vacuum even with a leak!!! For only $15!!!
Obviously these people are complete morons... and this device will *NEVER* reach 29+ in/hg. But it was funny to read how 'amazing' this thing was... and how stupid these people were.
THIS: http://www.harborfreight.com/25-cfm-vac ... 98076.html is the pump that WILL pull 29.2in/hg
