The Harbor Freight Pittsburgh is a 3 CFM Two Stage HVAC Vacuum Pump.
It is rated to pull a vacuum to 22.5 microns.
It will work with most any refrigerant, R134A and R12/R22.
Vacuum pumps are often are high priced units and can cost upwards of $500-$1000 dollars.
At less than $200 dollars this unit from Harbor Freight makes it more affordable for home DIY or part time HVAC technicians.
It could also be used on a vehicles cooling system but I only used it with a home air conditioning unit.
There is a sight window to see the oil level.
This is a nice feature since you will be able to see when the oil has become too dirty and needs changes, and also as to not overfill it.
The drain plug for the oil is underneath.
The motor has a fan behind a shroud that helps keep it cool.
Testing the unit it pulled a 3 ton split system down in roughly 45 minutes.
My final thoughts on this HVAC vacuum pump is it worked and it worked great.
I had no problem evacuating the system, it pulled it down the unit I tested it on relatively quickly.
I let this sit there and run for a good hour since it was a system broken open because they stole the copper from it.
I did pull it for an hour, I had no problems with it maintained its vacuum throughout the entire time.
It seems to start a little noisy and I think they mentioned it in the manual and after a couple minutes after it draws down it quiets up.
It is quiet now and running which is great.
I would recommend it for those working on there own systems and need a cheap unit to work with.
It could be used in a professional setting or as a backup although there are better units although more costly.
I am still testing the unit out and will update if anything changes.
As always be sure to read the reviews on forums or elsewhere to be sure a unit is a good fit for you.