How To Find a Low Side Service Port

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So your vehicle’s AC system is blowing hot air and you are ready to add some refrigerant, but where do you begin?

The first step in recharging your system is to locate the low side service port (or low-pressure port). Every auto air conditioning system has two service ports: one on the high pressure and one on the low pressure side. When recharging with AC Avalanche refrigerant, for safety, you will charge through the low side service port. Never charge through the high side port.

So, how do you find the low side service port?

Well, it’s usually located between the compressor and the evaporator on the larger diameter a/c line. First, find the compressor. It is driven by the fan belt near the radiator at the front of the vehicle. Here is what a typical auto a/c compressor looks like:

If you are having trouble identifying your compressor, you might want to try visiting this page and entering your vehicle information to see a list of compatible compressors for your engine:

http://www.autozone.com/cooling-heating-and-climate-control/a-c-compressor?filterByKeyWord=compressor&fromString=search&isIgnoreVehicle=false&newYmme=true

Next, follow the line from the compressor towards the evaporator. The evaporator is located near the firewall behind the dash, and directly under the windshield. The low side service port is usually in this line and will have a black or blue plastic cap that needs to be removed. On some vehicles, the service port is directly on the compressor. To make things easier, this is the only port to which the Avalanche quick coupler will connect.

Now that you know where your low-side service port is located, you can begin recharging your systems refrigerant according to the instructions on the packaging. To summarize:

Every A/C System has two service ports: A high side and a low side.
When recharging with AC Avalanche, you will only use the low side service port.
The low side line of the system will have a larger diameter metal pipe than the high-side.
The low side service port is usually located between the AC compressor and evaporator.
The low side service port will have a black or blue plastic cap that needs to be removed.
The low side service port is the only port to which the AC Avalanche coupler will connect.
Never charge through the high side port.