How To Vacuum AC System The Right Way

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To keep your AC unit running correctly, you must vacuum the refrigerant lines. If you have just installed your AC unit for the first time or have reinstalled it, it is important to vacuum the lines. 

There is already refrigerant in your lines. If this refrigerant combines with moisture, the moisture will freeze and clog the lines. Vacuuming the lines removes the moisture in your AC unit. 

“Pulling a vacuum” means removing contaminants like dirt, water, and air from your air conditioning system. For this to occur, you must lower the system’s pressure to reduce the water’s boiling point. This allows vaporization to occur.

Once vaporization can occur, it is easier to eliminate the harmful substances in your refrigerant lines. You want your AC system to be as clean as possible to operate at its best.

Is it Necessary to Pull a Vacuum on AC System?

Vacuuming your air conditioning system is necessary to remove air and moisture from your lines. If there is moisture in your refrigerant lines, it will not only cause your AC not to work as well as it could, but it could also cause your AC system to freeze. 

If your AC system freezes, this may lead to long-term damage. That’s why it is essential to vacuum your lines. It will save you money in the long run.

The main benefit of pulling a vacuum on your AC system is that it allows your system to run efficiently. This will save you money on repairs in the future.

What Happens if you don’t Vacuum your AC?

If you don’t vacuum your AC system, it will not work at its maximum performance. Vacuuming the AC lines removes moisture. Leaving the moisture can cause problems later on. 

If you don’t correctly vacuum your AC, it can cause more problems than just low efficiency. Problems include corrosion, mechanical breakdown, line restrictions, and system failure. 

How Often should you Vacuum your AC System?

You should vacuum your AC system after you install it for the first time. You should also vacuum your AC system anytime you reinstall it. 

Over time, air from the outside atmosphere will enter your AC system. This air has certain components, like oxygen and nitrogen, that you do not want in your system. Therefore, you will want to vacuum your AC system to remove this air.

Ideally, to keep your AC running at its best, you should vacuum it once or twice a year. A good way to remember to do this is to vacuum your lines before you change the filter.

How Long Should you Vacuum your AC system?

Allow the vacuum pump to run for at least a half-hour. It could take up to forty-five minutes. Watch the gauge until the vacuum level displays 29 Hg. This will ensure that the vacuum has removed all the excess moisture.

How to Vacuum Home AC System

1. Turn off your AC unit. 

2. Remove service valve caps. The service valve caps are gold-colored. You can find them where the refrigerant lines enter the condensing unit on the backside of your system.

3. Using refrigerant manifold gauge hoses, thread each service valve line onto its hose by turning them clockwise. 

4. Make sure the vacuum pump has enough oil by checking the sight glass. Add more oil if the sight glass shows the oil is not at the fill line. The oil is necessary to remove contaminants in your lines and stop the pump from overheating.

5. Prepare your vacuum pump next to your AC unit on a flat surface. 

6. Thread the center hose onto the vacuum pump’s intake valve. Turn the pump on.

7. The manifold gauge valves should be in the “open” position. The vacuum should be removing the air and moisture in your AC lines. As the vacuum is pumping, keep an eye on the left gauge readout. Once it reaches 29 Hg, shut off the pump and close the manifold valves.

8. After twenty minutes of the vacuum pump being turned off, the readout should still say 29 Hg. If it does, there are no leaks.

9. Disconnect the vacuum pump from the AC unit. Remove the refrigerant manifold gauge. If there are no leaks detected, you can add refrigerant or freon into the system.

10. Turn on your AC unit. 

Does Vacuuming AC Remove Oil?

No. Vacuuming AC does not remove oil. It only removes air and moisture.

If you see oily spots in your AC hose, this can indicate a refrigerant leak. A refrigerant leak detector can help you verify a leak in your hose.

To remove excess oil from your AC system, you will need to flush the system. To do this, you must first disassemble your system. After you disassemble your system, you can drain the compressor by putting it upside down for a few hours.

Reassemble your AC system and replace any parts that need to be replaced. After you fix the leak and flush the system, you must replace the oil that was lost. Too much oil can affect the heat exchange, not enough oil causes problems in lubrication.

Recharge your AC unit and see if it is performing more efficiently.

Can a Vacuum Leak Cause AC not to Work?

If you have used a vacuum to try to remove the air and moisture from your refrigerant lines to help your AC run more efficiently, but it did not work, you may have more severe AC problems than you thought.

Don’t worry just yet. It could also be a simpler, less expensive problem. For example, it may be that you just didn’t let the vacuum run as long as it needed to. The problem could also be a refrigerant leak.

If you do not have a refrigerant leak and the vacuum is still not fixing the problem, it is time to start looking at other possible reasons your AC is not running efficiently.

This could include thermostat problems, switches that have been accidentally turned off, a tripped breaker, a blown fuse or transformer, dirty coils or filter, or damaged components.

If you are not sure how to fix the problem, hire a professional. It is better to get it done right the first time rather than breaking your system even further.

What Happens to a System that Leaks while in a Vacuum?

Using a vacuum pump should remove air and moisture from the AC unit. This is the first thing you should do if your AC is not running efficiently. If your system leaks during this process, you will need to do the necessary repairs. 

To determine if you leak, you will need an electronic vacuum gauge that shows the vacuum level in your AC system. Follow the steps below to determine if you leak.

  • Follow the steps above to begin vacuuming your AC system. 
  • Once the gauge shows a 500 micron or lower vacuum, you will want to isolate the system from the vacuum pump, service hoses, and manifold. If the vacuum stabilizes and continues to hold less than 500 microns, you are in good shape.
  • If the vacuum slowly rises and then stops, there is still moisture in the system. This means you should continue with the vacuuming. 
  • If the vacuum gauge shows an atmospheric pressure, this means you leak. If your system can hold less than 500 microns, your system is leak-free.

If the vacuuming process works and removes the air and moisture, you know there is no leak. You can then do a charging process to test out the system.

How to Recharge your Air Conditioner

Once you have done any necessary repairs, you can recharge your AC’s system to function properly. 

To recharge your AC system, first, make sure your system has pressure gauges and that you have the proper refrigerant for your system. You will also need an infrared thermometer or a thermocouple-based meter to measure the temperatures of the pipes.

Begin by checking your unit’s charge. After you turn off your AC system, attach the hoses from the gauge manifold to the pressure ports. Turn on your AC system and let it run until it reaches steady operation─about 15 minutes.

Next, measure the temperature outside, the air temperature at the return of the unit, the temperature of the suction line, and the temperature of the liquid line. 

Check the label on the electrical compartment cover of your air conditioner for specific instructions for your unit. It will most likely give you a chart of the superheat and subcooling for different outdoor temperatures. 

If you do not have one of these charts, you will have to figure out which metering device your system uses. 

The method of charging you should use will vary depending on the type of refrigerant. Once you find the right method, slowly add the refrigerant. You should allow time in between adding small amounts. 

Check the temperature and pressure readings to determine if you should add more refrigerant. After the readings are stable, have your system complete a cooling cycle. If everything is running efficiently, you can turn off your unit and remove the gauges. 

Keeping your AC system running efficiently will save you money. Vacuuming your AC unit will help it run efficiently and save you money on energy each month. Vacuuming out the moisture will also prevent long-term damage to your AC system.

Anytime you install an AC unit or reinstall it, you should vacuum your refrigerant lines. Whenever your AC is not running as well as you hoped, vacuuming the lines can solve the problem. 

If you want to avoid things like corrosion, mechanical breakdown, line restrictions, and system failure in your AC unit, pull a vacuum when you need to.

If you are not comfortable doing repair work on your AC system, hire a professional. You do not want to cause more damage to your system if you do not know what you are doing. 

If you see oily spots in your lines, vacuuming will not fix this issue. The oily spots mean you have an oil leak. Determine where the leak is and fix it before you vacuum your lines or add more refrigerant. You should also flush the system to remove excess oil before you vacuum your lines.

The bottom line is, vacuuming your AC unit can be a smart thing to do. It will help you maintain your unit by keeping it clean and dry. You can do this yourself, but you can hire a professional if you are not comfortable doing it.

If vacuuming your lines did not solve your AC issues, you may have a different problem than moisture in your lines.