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Leaking low pressure A/C port

I recently tried to recharge my 1994 Saturn SW2 air conditioning. The system took the charge fine, nice cool air again. Yea! On disconnecting the adapter, I heard the sound of escaping gas. I was able to place my thumb over the port and block the leak, tried reattaching adapter and removing several times, but the valve will not fully seal. Placing the cap back on the port with a small piece of plastic food wrap (hi tech) stopped the sound, but obviously not the leak entirely. A couple of weeks and the a/c is back to blowing hot air.

Is there any way to encourage the valve to seal? Should I try the variety of refrigerant that seals leaks? Is there a better choice for blocking the leak than food wrap? If it comes to it, replacing the low pressure line, is that something a person who knows how to use a wrench but not much more can do?

Get a new shrader valve at any parts store.
It installs the same as a tire valve stem core. A little tool with two tabs is used to unscrew and install the valve.

Is The low pressure port on the compressor or somewhere else.
Get a new valve cap at the dealer or auto parts store. The cap should not allow a leak. Some service ports will leak a little . That is why the external cap is used. Put the cap on and check the port with a soap and water solution and see if it leaks then. high pressure port is red and low pressure port is blue, or markrd L;-low or H;high.
Be careful that you do not do something that will let all the freon out. as then you will have to have the system serviced professionally.

Yes, thank you both for your assistance. I take it that replacing the valve would, unless done with some speed I’m not confident of possessing, vent all the freon as is warned against. Both the hi and low pressure ports are centered on their respective hoses, not on the compressor itself. I don’t know if the system is now fully discharged or not. How does one tell?

Take your vehicle to an auto AC repair shop. And they’ll use one of these to replace the core in the Schrader valve while losing very little refrigerant.


Replacing the schrader valve is an excellent idea especially with the tool. Ask how much the cost is before signing the work job order.
I would still check for leaks myself because if you take it to an a/c service they may find a larger leak that is the problem. Only an A/C tech can change hoses or a compressor that has leaky seals.
You still have freon in the system as a certain amount will remain even tho much has leaked out the system . Enough that no moisture infiltrated the system.
Also there is an a/c pressure sensor usually on the high pressure side which will shut down the system to protect the compressor. if the pressure rises too high or drops too low the a/c will not turn on.
You need a Haynes manual
You stated that your system would pull in a freon charge. That indicates that the compressor is working.
and pumping. When you added freon did you use a can with a meter on it.??

My 2000 dakota pickup will set an OBD code using ON BOARD DIAGNOSTICS .All cars now have this feature.
You my be able to read the code by using this ignition switch scheme. On your vehicle you need the manual to see how to do it.( My OBD code read AC pressure transducer) . I replaced the pressure transducer now everything is ok
On my dodge Dakota I switch the ignition on-off-on off- on within 30 seconds. Do not turn the key far enough to start the engine. My electronic odometer then read out the code . Look up the code in the manual to see what the code means.
I think that the problem is a sizable leak. Good Luck!