Air Conditioning Vacuum Pump



Every time you use your air conditioning vacuum pump, do yourself a favor and change the oil.


I mention this first off because I've known a lot of technicians who don't change vacuum pump oil until it turns a dark color.


The frame of mind seems to be "Never mind what the owner's manual says, it's still pulling down to 29 Hg, so why change the oil?"


For those who might not know, the oil not only lubricates the pump; it also absorbs contaminants removed from the system.


If you have a good set of gauges that aren't leaking, you can use them with your air conditioning vacuum pump to evacuate systems that are 5 tons and smaller.


On larger systems, use copper tubing and isolation valves, directly off the vacuum pump, and don't use a manifold gauge set.


Attatch a micron gauge to the system, again with copper tubing and an isolation valve.


On larger systems, if you use a high capacity air conditioning vacuum pump, you'll need 3/8, 1/2, or 5/8 hoses, with the same size fittings on the system and the vacuum pump.


A high capacity vacuum pump simply won't pull its full capacity through 1/4" hoses, schrader valves, and fittings.


If you don't have a high capacity vacuum pump, setting up two or more vacuum pumps at different access fittings around the system will speed up the evacuation process.


Remember: vacuum to 500 microns.

If your air conditioning vacuum pump won't pull down to 500 microns, get one that will.

If the system won't pull down to 500 microns, you have a leak, or a lot of moisture in the system.


Oil turning milky white is a sure sign of water in the system.


Repair the leaks, and find the water and moisture and drain it out of the system.


You can also use an air conditioning vacuum pump to drain oil from large compressors and systems.


Hook a hose up from the liquid access port on a recovery tank to the oil drain port, and hook the vacuum pump up to the vapor port.

The vacuum pump will pump the can into a vacuum, and the oil in the system will be pulled into the can.

Since the vapor port is above the top level of the can, oil won't be drawn into the pump.


I hope these tips will help your air conditioning vacuum pump last a long time, and will help save you some time on repairs.

And please, feel free to contact us with any specific HVAC questions you might have, including questions about air conditioning on Guam, or refrigeration on Guam.

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