No pressure in AC system

Question

04 hyundai sonata, 0 pressure low/high ac gauge

i know this is a dumb question but i'm pretty new to repairing your own car i recently got a high/low gauge so i can re charge my r-134a refrigerant and when i went to test the pressure to my gauges like scotty did to see if there was another problems with the pressure both high and low read 0 and i made sure the valve was on open so it could build pressure in the gauge, so could it be my condenser or maybe a leak in the lines im going to check the lines tomorrow for any visible holes but how would you guys recommend i go at this

also if this helps i bought the car about a year ago and the ac was blowing hot air then, i don't know why i just decided to start caring about it now

Chuck Tobias · Accepted Answer

If you have a large leak there will be oil visible at the leak point. If the leak point is not obvious, you could pull vacuum then charge in a little refrigerant with UV dye to find the leak, or use an electronic detector. (You need a vacuum pump in addition to the manifold gauge set.)

With no pressure in the system it has been exposed to atmosphere and at a minimum in addition to whatever else needs to be repaired the drier will need to be replaced, with about an ounce of PAG oil put into the new drier.

However - if you are not familiar with working on air conditioning and don't have anyone experienced to show you, it really would be best to have a mechanic work on it. It is very easy to make things worse or even injure yourself working on AC.

jshep91 · Answer

If you're not sure how to work on cars, take it to a mechanic. There's no shame in doing that. Most people don't know how to properly work on air conditioners. Air conditioners are nothing to mess with if you don't know what you're doing. I repaired my air conditioner myself, but it took all day, I watched a ton of videos before I did it. I'm an aerospace engineering student. I replaced my condenser and I replaced the accumulator/dryer. Almost 2 years later, it still blows cold, even in 90-degree weather.