A/C question
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
All I can say is my Harbor Freight pump is the only thing I've ever bought there that I didn't use once and throw away. Pulls to 28 with ease on both my gage sets. I do have a 5 hp, 30 gallon tank and I'm **** enough to let my own stuff sit overnight to make sure it's tight. Most of the cheapo hoses I've bought fare much worse and start leaking after a single job. If Central Coaster hadn't supplied his own hoses when I did his car, it would never have gotten done.
Drifting
Joined: Nov 2003
Posts: 1,634
Likes: 4
From: Northern NJ
St. Jude Donor '04 & '05
All I can say is my Harbor Freight pump is the only thing I've ever bought there that I didn't use once and throw away. Pulls to 28 with ease on both my gage sets. I do have a 5 hp, 30 gallon tank and I'm **** enough to let my own stuff sit overnight to make sure it's tight. Most of the cheapo hoses I've bought fare much worse and start leaking after a single job. If Central Coaster hadn't supplied his own hoses when I did his car, it would never have gotten done.
I obviously can't say how well yours works but as far as mine goes on three different gauges I couldn't get more than 26 inHG from it also using a 5HP, 30 gallon air compressor. And the only way I could get it to 26inHG was to exceed the 90psi max recommended input. However the converted ac compressor pulled right down to 28+ inHG no problem. So either my gauges are pretty close, or my homemade compressor/pump pulls a perfect 30inHG. (not likely)
And for reference I'm less than 500ft above sea level.FWIW I was on the fence for awhile about if I should use the HF pump (at 26inHG) or find something else. The following article is what made the decision for me.
http://www.aircondition.com/tech/que...C-Vacuum-Pumps
Whatever way JamesRS goes and however he gets there, I wish him lots of luck.
Drifting
Joined: Nov 2003
Posts: 1,634
Likes: 4
From: Northern NJ
St. Jude Donor '04 & '05
I would have never thought about using the engine as a vacuum pump. And that's after using my old vacuum/fuel pump gauge as one of the references when measuring the HF and homemade converted compressor pumps too. 
Whatever works, works. There are usually many ways to get to the same end result. JamesRS, my offer for the pump still stands if you want it.
Thread Starter
Corvette Enthusiast
Joined: Oct 2003
Posts: 523
Likes: 139
From: La Quinta CA
Sorry for the delay in the reply guys. Thanks for the instruction on what I needed to do. While I was replacing some vacuum lines and generally just doing some PM work on the engine compartment I found that a vacuum operated coolant controlling switch of some sort was being obstructed by some of the under hood hoses. As soon as I moved the hoses and replaced the engine vacuum check valve the amount of cool air coming out of the dash vents changed significantly. I think the heater vents were being held partially open. In any case, the air coming out of the vents now is pretty cold and the pressure on the low side is about 30. (I forget what the high side was) I'm going to keep and eye on it, but for now I don't think I'll need the vacuum pump. Thank you for the generous off though. That was very nice. And thank all you guys for the great advice.
