What would cause an Air Conditoning unit low on Freon ?
Answers:
You can get a leak from any joint in the freon path. A "schrader" valve can deteriorate and leak - these are the ports where the technician checks the levels. A good service tech will have a "sniffer" to detect leaks and determine a course of repair. Sometimes just a reheat of the connecting joint will correct the problem but you need to find it first. It would be a good idea to have this fixed so you don't run dry and hurt your compressor unit. It is also a violation of EPA standards to discharge freon into the air.
Other answers:
A leak.
A leak.
Sometimes the units get pinholes in them that the freon escapes from.
It's a leak.
Simple
1. You've used it all and it needs to be recharged by a qualified and certified professional
2. You have a leak in your line or system, see #1.
Key point. Get someone to handle it. Freon is some nasty stuff.
using it. and this is an old unit. freon is outlawed in the usa. due to its adverse effect on the ozone. buy a newer one. they are cheap now.
it could also just be low from the usage
AGE! more details would help.Seeing any green on the lines anywhere?
you have a leak somewhere for sure, mine did the same. hvac people came out and wanted me to pay them $200 to squirt something in there to seal the leak. wow! i told them no thanks
U have a leak, dude.
Everyone Else had some crazy answers there are plenty of causes for being low it could have never been charged properly,could have a leak depending on age,but for the record a unit never needs freon if properly installed and serviced reguarly. CALL A PROFESSIONAL HVAC GUY