Category: ac evacuation and recharge

Evacuation and auto ac system air contamination

Evacuation and Auto A/C system air contamination.

Every time the auto A/C system is opened for a component replacement or any other type of service the service must be properly evacuated. Pulling a deep vacuum will ensure that all the ambient air that went inside the system while it was opened will be evaporated out of the system.

The negative impact of air contamination on the ac system will be noticed right away. Some of the signs of air contamination are noisy compressor operation and decreased overall auto ac performance. The air can’t be condensed inside the air conditioning condenser and only occupies the space of the refrigerant making the condenser less efficient and not allowing the process of de-superheat, condensation and subcooling that happens in the a/c condenser.

Auto A/C system Air contamination field test:

With 0% air contamination

High Side :165 PSI

Low Side: 32 PSI

Condenser temperature differential:38 Degrees


With 7.7 % Air Contamination

High Side : 200 PSI

Low Side: 31 PSI

Condenser temperature differential : 65 degrees


With 18.9% Air contamination

High Side:400 PSI

Low Side 45 PSI

Condenser temperature differential 102 Degrees


What damages could cause the air contamination in the car ac system.

Auto A/C system air contamination rises the overall pressure in the system. Higher than normal pressures will force the ac compressor. Higher pressures cause higher temperature that could change the oil viscosity and properties. A/C system air contamination will keep the condenser fan assembly operating at maximum capacity because of the inefficiencies of the condenser to change the refrigerant from vapor to liquid.


How to check for auto ac system air contamination ?

A refrigerant identifier can be used to quickly check for air contamination and refrigerant cross contamination.


Do you need assistance checking your auto ac system for air contamination?

Auto A/C Repair LLC. provides auto ac repairs near your area. Call Today to have one of our ASE certified mechanics check your air conditioning system for air or other contaminants in your vehicle’s ac system.

freon for car amount

Freon for car amount

After servicing the a/c system in your vehicle you need the exact freon amount for your specific car and the type of refrigerant.

Compressed air mixed with the HFO-1234yf (R-1234yf) forms a combustible vapor.
The vapor can burn or explode causing serious injury.
Never use compressed air to pressure test HFO-1234yf (R-1234yf) service equipment or vehicle a/c systems.
Air conditioning refrigerant or lubricant vapor can irritate your eyes, nose, or throat.
Be careful when connecting service equipment.
Do not breathe refrigerant or vapor.
auto ac evacuation and recharge. Chevy auto

My car AC compressor has blown 15 minutes after a regas/recharge. What could be the cause?

Vehicle ac evacuation and recharge near me

Before replacing any components that carry refrigerant through the system, the existing refrigerant must be removed. On a typical 80° F Day, a fully charged system will have over 80 psi of pressure. Opening a fitting or union will allow the refrigerant to escape into the atmosphere. Such a procedure I not only extremely unsafe; it is illegal and environmentally harmful.


How much does it cost to evacuate and recharge AC?

The cost of evacuation and air conditioning system recharge will depend on the type of refrigerant your system has installed, and the amount required to get it fully charged according to manufacturer specifications.

Call Us today to find out this information.



Do you have to evacuate AC system before recharging?

After repairs have been performed on the A/C system, or any time a system has been opened, it must be evacuated. Air and moisture will enter an open system. Moisture from humidity in the air can form destructive chemicals inside the system when mixed with refrigerant and oil, and can cause a breakdown of the newer synthetic oils used in R 134A systems.

Also water in the system can ice up in the expansion valve and block the refrigerant flow. These chemicals can corrode metals and attack rubber parts.

During evacuation, as the pressure inside the system lowers, so does the boiling point of the water in the system. Water can vaporize and be withdrawn by the vacuum pump.


How do you evacuate an AC system on a car?

You can use either a charging station or stand-alone vacuum pump. According to EPA ,when evacuating a vapor compression system, the vacuum pump should be capable of pulling 500 microns (29.92 hg.) of vacuum. After properly connecting the service hoses and removing any refrigerant , start the vacuum pump and open both sides of the system, exposing it to vacuum. Once the vacuum level reaches specification, continue pulling the vacuum between 5-60 mins depending on the type of system repair and the time the ac system has been opened. Close all valves and turn the vacuum pump off. Wait for 1-15 minutes and note any loss of vacuum using your ac manifold gauges. If vacuum is lost, it means system leakage is present.

If the vacuum pump is turned off too soon, some of the moisture in the system will be left behind. Before turning off the pump, close off the A/C system to the atmosphere to prevent air from being drawn back in.

Where can I find a professional auto air conditioning service?

We specialize on automotive air conditioning systems. We have ASE certified auto ac mechanics near you.

Contact Us


A/C low pressure & high pressure service valve ports

Car a/c service ports.

Most Air conditioning systems use Schrader valves at their service ports. These valves are similar to tire valves, although they can never be interchanged. They are covered with caps (resembling tire valve caps), containing O-rings.

Unless the system has been completely discharged due to a leak, recover the refrigerant using the appropriate method and equipment before servicing any hose , line, or fitting.

Which port do you charge AC in car?

Although charging the system can be performed through either the high side or low side when the engine is not running, it must be done only through the low side when the engine is running. This safety measure prevents the high-side backpressure from entering the refrigerant container and possibly causing an explosion.

Use the manufacturer’s specification for refrigerant capacity. On most newer vehicles, a sticker is affixed in the engine compartment indicating the type of refrigerant , type of oil, and the refrigerant capacity of the system.

How do you add freon to your car’s air conditioner ?

The most accurate method to assure that the proper amount of refrigerant has been added to the system is to use a charging station that can be programmed to deliver a specified amount. It is crucial that the exact amount of refrigerant according to specifications is used. Overcharging the system can cause damage, and undercharging will cause poor performance.

Where is the AC service port?

The location of the ac service port will depend on the make, model, year, and refrigerant type of the vehicle. The easiest way to find the ac service port in any car is to follow the lines from the compressor all the way into the firewall. The A/C service ports will be at some point between the ac compressor and the firewall.

Are all AC service ports the same?

The low side service port the  is the smaller of the two ac service ports. In all car new models, the high side fitting and low side fitting are different diameters .This prevents connecting the service hose to the wrong fitting. Systems with different refrigerants also require differently designed service fittings. This is to discourage technicians from putting incorrect refrigerant or oil in a system and contaminating it. Do not try to circumvent them with adapters.

R-134a refrigerant systems use quick-connect fittings, like the type used on air tools, and this time the low side port is smaller of the two.

R-1234yf refrigerant systems use quick-connect fittings too, but with different diameter to prevent contamination with R-134a refrigerant systems.

Some older systems have three-way stem-type service valves at the compressor inlet and outlet ports.

Your service tools must have the proper connectors for the various service fittings, and the equipment used on one system should not be used on another.

Do you need assistance with your vehicle ac evacuation and recharge ?

We have auto ac repair mechanic near you.