A working AC system is important for driving comfort, especially in hot weather. When the AC system stops blowing cold air, it usually means a leak or blockage must be fixed. Vacuum Car Ac system, which removes air, moisture, and contaminants, is an important part of the repair process. However, most DIYers cannot access a vacuum pump to perform this task.
The good news is that there are a few simple ways to effectively vacuum a car’s AC system without a vacuum pump. We will explain what vacuuming does, why it’s needed, and how to use common household items to vacuum Car AC system without a pump.
Why Vacuuming the AC System is Necessary?
Before recharging your AC system with fresh refrigerant, it must be free of air, moisture, and debris. It ensures optimal cooling performance and prevents damage to the compressor. Exposing the system to moisture and air can form corrosion and sludge. Debris can clog orifices and interfere with the proper refrigerant flow.
Vacuum Car AC system removes all of these contaminants by lowering the pressure inside the system so that it is far below atmospheric levels. This causes the gases inside to expand and evacuate through the vacuum pump rapidly. The deep vacuum that remains sucks out any moisture or debris stuck inside the tiny passages of the AC components.
While professional shops use expensive vacuum pumps to achieve 25-30 inches of mercury vacuum, we found some simple DIY methods that come surprisingly close. And you only need about 80% of that pro-level vacuum to dehydrate and thoroughly clean a car AC system.
Easy Methods to Vacuum Car AC System Without Pump
Method 1: Refrigerant Canister and Recovery Machine
For this first method, you’ll need:
- Automotive refrigerant recovery machine
- Empty the refrigerant canister, clean, and evacuate
A recovery machine connects to your car’s AC ports with hoses and uses a compressor to pump out old refrigerant into an attached canister. While designed mainly to safely capture and store refrigerant, most models also have a vacuum setting.
Follow these steps:
- Connect the recovery machine to your car’s low-side and high-side AC ports with the hoses. Make sure the ports and connectors are clean.
- Connect an evacuated refrigerant canister to the recovery machine’s canister port.
- Turn the machine on and select the vacuum mode. Enable any options for extended or deep vacuum if available.
- Run for 15-20 minutes until the machine indicator shows a vacuum between 20-30 inches of mercury.
- Close the AC ports, disconnect all equipment, and immediately cap the ports to hold the vacuum inside the system.
The deep vacuum created by the recovery machine sweeps moisture and debris through the evaporator, hoses, drier, and condenser to thoroughly clean the system. It’s ready for a leak test followed by recharging the refrigerant. Just make sure to check for oil level and compound before finishing the job.
Method 2: Refrigerant Charging Hose and Recovery Cylinder
For method 2, you will need:
- Refrigerant charging hose with manual gauge
- Used refrigerant recovery cylinder or other airtight tank capable of vacuum
DIY-focused refrigerant charging kits include gauged hoses that connect to low and high-side AC ports. While mainly used for adding refrigerant, they can also draw a vacuum with the right cylinder tank attached.
Follow these steps:
- Connect the charging hose to clean Car AC system ports, allowing access to the low side and high sides.
- Attach the center port of the charging hose to an empty recovery tank or cylinder capable of holding vacuum pressure.
- Open the tank’s valve fully and operate the handle to slowly pull a vacuum. Monitor the progress with the gauge in PSI.
- Continue pulling the vacuum for 10-15 minutes until you are unable to draw down past -14 to -15 PSI relative to atmospheric pressure.
- Immediately close AC ports and remove equipment to trap the vacuum in the system.
The vacuum created by hand pumping the tank is weaker than a pump but still enough to effectively clean moisture and debris from an AC system with 10-15 minutes of effort. It’s a cheaper, simpler method than owning an expensive vacuum pump setup.
Method 3: CO2 Tank and Dry Ice
Our third vacuum technique uses inexpensive dry ice and the pressure inside a portable CO2 tank:
Materials:
- 20 lb portable CO2 tank, half full
- 2 lbs of dry ice pellets
- Masking tape
Follow these steps:
- Wrap 1-2 lbs of dry ice pellets completely in masking tape, forming an airtight pack around the CO2 ice.
- Connect the CO2 tank’s hose and trigger mechanism to the low-side service port of the AC system.
- Actuate the trigger intermittently to pressurize the system to 100-150 PSI with short CO2 bursts.
- With CO2 pressure held in the line, place the taped dry ice pack into the largest AC vent opening. Seal it completely around the edges with more tape.
- Wait 10 minutes for the dry ice trapped inside your ducts to fully sublimate from solid to gas, creating an extreme vacuum effect strong enough to suck contaminants out through tiny leaks in the evaporator case weld seams or gaskets.
- Remove the vent cover, take out dry ice remnants, and pull a partial vacuum with the CO2 tank to draw down to 0 PSI on the gauge.
While not quantitative, the vacuum produced by CO2 tank pressure with sublimating dry ice can match a pump for deep cleaning abilities. It saves money by using cheap supplies from a restaurant supply store.
Conclusion
For the air conditioner to work properly and keep its parts from breaking, it must be clean and dry. You can fill the refrigerant with an easy-to-use kit, but it’s just as important to clean out the system first. As we discussed how to vacuum a car’s AC system without a pump, you know you don’t need a special pump to do this important job.
You can get the strong vacuum you need with things you already have at home, like a charging hose kit, a refrigerant recovery machine, or even a CO2 tank and dry ice. To get great cooling all summer, follow the steps we’ve laid out to get rid of any dirt or dust in the system before you test for leaks and add more refrigerant.
