Thread: A/C button no longer turns on compressor. Ideas?

You either bite the bullet and buy one, rent one or borrow from an Auto parts store, you know those borrow with your credit card and return or you own it deals.
The best are Oil pumps, dry diaphragm ones don't pump as low a pressure.

I purchased a re-built industrial Plasma machine pump, Oil, I think its about 1 1/2 inch Dia input, from a Semiconductor company I worked at having a clearance sale. All the used ones not re-built were gone, this was left because the lead wasn't wired up. !!!
Wired it up, added lots of reducers and away I go !!!
Had it over 20 yrs !!! makes a really nice sound as it pumps. definitely overkill, but the price was right.

I'll rent one if I can, otherwise I'll buy one. Do I have to buy the two gauge shabang deal too? Or is it possible to just hook up the pump to the line and let it suck away

the gauge set allows you to isolate the vacuum pump with a valve and fill with freon without allowing Air into the system.
You cant just turn off the pump !!!
If you rig it up to do the same thing you can do without the gauge set, but why ?
You need the Hi and Lo reading when you are checking a system that got problems.
Its also helpful when charging to monitor the Hi side to prevent overpressure.
And they are not that bad, from about $40 on sale at Harbor Freight to $60 - $80 at the local Auto parts store.

Went Vacuum pump hunting. All but one of the car stores were wondering why I needed it. Advance Auto sent me to Lowed/Home Depot. While at Lowes the guy said that's only used for car's AC system, check Auto Parts store.

Napa does have them, my store had the 3cfm one for $189, while they are over $200 online here. They didn't have them in stock, so I went to the next location and asked around.

Finally after going to Autozone, Advance Auto Parts, Napa, Lowes, I was about to give up, but then remembered about Car Quest. The guy I worked with knew that the Vacuum pump is for the AC lines. They had them for the wiping $130 for the 3cfm model. It should be here tomorrow, I'll pick it up and post pictures.

Now I tried to find a AC Manifold, Car Quest did have them for $130 but those were too good/professional. I'm gonna see if anyone I know has them, but I think I saw Autozone having a mid core set for $50.

Vacuum pump came in yesterday, I hooked everything up to the AC manifold.

Now I wish I bought the Harbor fright manifold, apparently this $60 autozone one does not show vacuum! The Vacuum pump does have another port, so I could put a gauge on it that would be more accurate.

Anyway I pumped the system for about an hour and a half, I noticed that the vacuum pump would change noises when there is something to pump, and when it just seems like nothing is left.

Refilled it and will take a drive today to see how it does

yes that's right, if the sound changes too quickly you know you have a closed valve somewhere, but i don't think the R134A connections have the issues the R12 ones had.
The vacuum gauge will only tell you rough numbers, either pounds or inches.
The water vapor pressure is much lower than that, so it doesn't matter.
30 minutes is barely enough, and hour is good, anything over that is being safe !!!

It's interesting, it wouldn't do it right of way, but about 5 minutes in. That's after it's been pumping for an hour and a half. Now it would start pumping again because when you disconnect lines it lets some air out/in.

I don't understand, the only part that lets air in is the part to the Freon on a R134A gauge set.
How did you connect the pump? normally you use the line that goes to the freon, but I have used the line to the Hi gauge on an R12 gauge set, that way didn't let any air in from pump to fill.
Since my pump is set up for R-12 I have not had to solve the connections to my R134A gauge set yet.

The instructions read for plugging the pump to the middle line (yellow). The set that I have uses the middle line to pump new freon in, but I checked and it also does suction.

The manifold I have only lets you view the high pressure side, are you supposed to use the vacuum pump on low press and high or just on low? I was under the impression on just low side.

yes that right, the pump normally connects to the yellow, or middle connection.
after you finish pumping shut the valves to the high and low side, then dis-connect from the yellow, connect up the freon, then burp the Air out of the yellow hose with a puff of freon, wear your gloves and goggles, then open the valves and fill the system.
then shut the high side, start the car and complete the fill.
This is how i was shown for an R-12 system when i started !!
R134a is the same, different connections and pressures, and Oil !!
the R134a hoses to the high side and low side are valves and sealed so don't open the valves when the middle port is open.
I keep an empty can on my yellow hose so its sealed.
I have often thought it would be a good idea to add a tee and valves to the middle port so you can vacuum the yellow hose and then shut the vacuum off and open the freon.
So i used the red on my R12 set up for this after pumping both sides, but this is not normal.