AC went out in 2011 Sonata replaced the compressor and if worked fine for a while.Now it works sometimes and sometimes just blows hot air. Where do I go next?

in this particular problem firstly you have to analyse the power ampere of ac because sometimes power not flows properly and due to this ac compressor cant work properly because they cant get their requirement power . secondly you can check gas in compressor because sometimes due to tiny wholes gas gets released and it causes in hot air blowing

If the temperature control is on cool....sounds like you have other problems with AC. ( compressor not working, needs R134,) Check under the hood for a box that has fuses in it, their are also relays in it. Look for the relay marked AC.

start off with the cheap possibilities and make your way threw.
I'd start off with replacing Air Charge temperature sensor, make sure your AC Hose isnt leaking anywhere, if those dont solve it then replace ur AC clutch, last chance would be replacing AC compressor. sometimes the compressor will malfunction randomly. or the AC clutch might malfunction aswell. covering these steps somewhere along the line you will have working AC again! good luck

A/C compressor clutch coil going bad . What is the 10amp fuse # F1.01

Have the change and pressure readings verified, the system may have a a major undiagnosed leak of refrigerant that went unrepaired.

either your compressor or compessor clutch is bad or the system needs charging.

See if the gauge goes to 100 ,look to see if the clutch on the ac compressor is cutting off,and then back on.

I would check the following possibilities:
1. Is compressor clutch working? - You need to do this when the ac is blowing hot air only - locate compressor drive pulley on engine - rubber belt wraps around it. Start engine and set to max ac. When the ac is blowing hot air, look at the center of the compressor drive pulley using a good flash light - watch it for a while, it should be spinning with the pulley - this means the compressor is engaged. If not, the compressor is not engaged. If your ac is blowing hot air, then the compressor should be engaged and running (trying to cool). If it is not engaged, then your compressor clutch is probably going out. Could be low voltage to clutch, but more likely the clutch is worn out and only working some of the time. Note: if working normally, the compressor clutch will engage and disengage in cycles- but the air should always be cold. If clutch is bad, compressor would need to be replaced (sold as one unit). This is tricky to diagnose and could take some time - you need to do it when ac is blowing hot air but set to max cooling.

2. Low on refrigerant or refrigerant has moisture in it? If your ac blows cold initially after being off for a while, then heats up, and continues to regularly cycle back and forth between hot and cool air, then the system may be low on refrigerant or the refrigerant may have moisture in it that is freezing and restricting refrigerant flow. An a/c shop can check refrigerant level and even replace refrigerant if moisture is suspected.

Could be other issues, but I would start with these.

Good luck

its probably the compressor cutoff switch cutting your compressor off at the wrong time and causing your ac to blow hot. that switch is under your hood right on top of the engine easy to get to. I hope that helps you out!

sound like ac vent or air door is not open.your ac mode switch is bad or the ac air door actutator is not getting vacuum .check vacuum lines to ac switch.besure disable air bags when working around steering area or dash.