Autozone will loan you one, with a deposit on your CC for the full price. When you bring it back, you get a refund.
Wouldn’t be a bad add for the Automotive committee to have a single-stage. They are anywhere from $175-300.
[edit] Also, a nice set of R-134a gauges would be nice.
chuckle “Full vacuum”, eh? I suspect that is for various values of “full”. 
— Zach
HF claims 28+" Hg. I don’t really believe that.
The one I own works as advertised provided it’s hooked up to a compressor capable of sustaining the required supply of air. It quickly and easily draws down to -28psi on the A/C gauge, same as the old electric single-stage I used to use professionally. For occasional use, it’s hard to beat. If you’re going to use it frequently, investing in a good electric unit can help save your air compressor from the not-insignificant load and the rest of the shop from a shortage of compressed air. Hardly seems like a challenge for the new compressor, but if everyone is frivolous…
Many shops have used that for years. Run it a minimum of 3 minutes (was 15
minutes in the old days if you want to wait). The longer the better.
Is any of you master mechanics around DM today that could help me recharge my AC system on my Prelude? I just changed the compressor, dryer, and expansion valve. The Alldata info says the things below, but was stuck on whether for the oil I add up all the figures if I’ve flushed the whole system, or if I just use the 4.5oz that came in the compressor and that’s the total amount the system needs? I’m heading up there now to do some other things, and will bring all my hoses and gauges if anyone is around that could help me. I’ve done it before, but a long time ago. Don’t want to screw it up. I need to evac and leak check also.
Refrigerant capacity: 750 +0/-50 g (26.5 +0/-1.8 oz) = Two cans? or Three?
Condenser 25 ml (0.85 oz)
Evaporator 40 ml (1.35 oz)
Line or Hose 10 ml (0.34 oz)
Receiver/Dryer 10 ml (0.34 oz)
Leakage Repair 25 ml (0.85 oz)
Compressor 130 ml (4.40 oz)
Note: Volume of old compressor should equal oil drain from new compressor, but not more than 50 ml.
Anyone? Bueller? I’m here in the Common area. Any help?
Text me at 8178750663 and I’ll meet you in there is you can help me!!
I have a good vacuum pump that I could loan to DMS…it is currently residing in my storage unit, for use on that odd occasion that I do AC work…I’ll bring it up next time I am up there…is there a process for loaning that item?
Basically here: https://dallasmakerspace.org/wiki/Rules_and_Policies#Loaning_of_Tools_.26_Equipment_To_The_Makerspace
(there’s a small issue with these instruction since Ops split in half, but we’ll fix the instructions “soon”)
Ok, so I am here, and I have brought the pump to put on loan. I have cleaned it up, put a new cord on it, and verified it works. Is there somewhere I should put it? @Brandon_Green
Sometimes, when it has sat for a long period of time, it will seize.
To get it going, just loosen the Phillips head screws on the head and then plug it in and then tighten the screws down. Please take care not to strip the heads. They don’t need a lot of torque.
There needs to be oil in it, and it uses plain air tool oil. Note the level, it doesn’t require much oil:
Never seen a vacuum pump like that before.
I put it next to the tool box. If it ends up being a nuisance, I can put it back in storage after the Summer…
I’m going to use it this weekend to pull down the truck’s system. I’ll report back on functionality.
I connected it to some AC gauges there in the shop and it instantly pulled them down as far as they would go, so I know it is working. Like I said, if you don’t hear it pumping, unplug it, loosen the head screws a little, then plug it in and as it is running you can go ahead and tighten the head screws back down. It was working fine earlier though.
On the shelves above the chemicals would be good, thanks. I need to do some organizing of those shelves soon.
I was in last night and here’s what I have to report:
The pump fired up fine and seemed to pull a vacuum. The “U.S. General” manifold set only registered 14 inHg, but I suspect that is an offset error in the gauge set itself. I did not attempt to use the adjusting screw on the face of the low-pressure gauge. The gauge and hoses seemed to hold a vacuum when the manifold and quick-couplers were closed (approx 5 minutes). We also have a Robinair gauge set, but the black vacuum hose from the pump will not fit on the middle connector of that manifold, so I was unable to test with that.
Unfortunately, I must have a leak somewhere in my AC system. It leaks back up to 1atm slowly. This is not surprising, as I had to replace the compressor (after it seized), accumulator, and condenser coils (highly recommended by everyone as they can’t be properly flushed). I suspect I’ve got a leaky joint, even with the new o-rings. My plan is to pressurize the system with dry Argon, since that’s what I have on hand, and use a combination of soapy water and a stethoscope to find the culprit(s).
Two asides: 1) The snap-ring pliers are in the roller cabinet drawer labelled “zombie defense” … an unlikely place for them, and 2) would Paul be ok with adding a standard flare for a r-134a yellow charge/evac cable to the compressor, in place of the existing black hose?
— Zach
Sorry, I should have posted my thoughts on the pump instead of trusting it to assumptions:
YES, any modifications anyone needs to do to the hose or fittings to make it more usable is perfectly fine with me. I had just bodged that hose up for the connections I had at the time.
As a follow-up to the leak in my AC system: Turns out that I had overtightened the low-pressure cycling switch on the side of the accumulator.
Using my bottle of welding argon and a pressure regulator like this one:
http://www.amazon.com/Uniweld-RHP400-Nitrogen-Regulator-Connection/dp/B008HQ6GXO/ref=sr_1_1
I was able to locate the hiss even without soapy water.
Once replaced, the system held pressure and vacuum without incident and I, once again, have A/C in the truck!
[edit: One might wonder why over-tightening something would make it leak. This happened because the nipple on the accumulator is aluminum and the part of the pressure switch which screws onto it is plastic. Apply too much torque and you get a crack right down the side. Doh!]
