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Discussion Starter #1 (Edited)
Greetings.

My son and I now own a 2013 Sonata GLS 2.4L with approximately 75k miles on the clock. Earlier this week A/C stopped working. Lights and fuses are good. Gauges show 80lbs on each end but compressor just won't click on.

Is there a relay somewhere I should be looking at? My googling shows the most likely culprits to be compressor or control panel in dash. It also seems that the a/c clutch is electric , not magnetic?

Any guidance is greatly appreciated.

M5
 

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" It also seems that the a/c clutch is electric , not magnetic?"
Me: It is both, electro-magnetic. It need electricity to create a magnetic field which engages the belt driven pulley.

1st, determine if the AC compressor clutch is engaging. If it is but you have no cooling, then it may be compressor or R134a refrigerant (commonly known as Freon) related issue.
If AC clutch is not engaging, then check if the AC relay is bad. Is the relay getting a "ON" signal on the input side?
If the relay is turning on and sending the compressor the voltage to engage clutch, but clutch does not engage, then it is your compressor clutch. if no signal from the relay, it may be a number of control issues. Low refrigerant, sensor sees low pressure - wont close.
If you jump the AC relay, if you know how, it should start a good compressor, even if refrigerant is low. Easier said then done, compressor is usually buried deep down.
If you know the relay, compressor, clutch will work if bypassed then the problem is the controls.
Controls issue may mean a failure or a sensor wont close. The sensing bulb, if it has one, may be bad and said no-go. Or R134a too leaked out. If it is the control circuit, it may be as simple as a loose connector or bad txv which is very hard to replace.
Leaks are very common. I'd start by making sure compressor clutch and low Freon are not your problem. Don't go over your head. It's a process of elimination, most times. Good luck.
 

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Discussion Starter #4
I'm sure that the compressor is not engaging. I'm not able to find a relay for the A/C switch like my other vehicles have. Where might the A/C relay be located. I found that there is a fuse in the passenger compartment fuse box and a fuse in the box next to the abttery under the hood, but no relay.

Thanks in advance.
M5
 

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Welcome to the Forum!

Using enhanced scan tool:
You can use an enhanced scan tool to monitor AC on /off. monitor relay, even monitor temp sensor on evap core, switch signal, pressure sensors...etc Usually can diagnose it in car.
If you turn on the ac by hitting the AC button the Scan tool will tell you if its on or off. This would eliminate the panel inside the car.

If relays and fuses good, PSI of 80 is high enough for compressor to function. (should really use a set of gauges to monitor high side and low side when system is set on. (if you turn the system on and NO PRESSURE changes occur, that means there is no compressor operation. Even if there was a massive amount of air, you would see the low side drop to a pressure below the allowable limits and would cause the compressor to turn off... then turn back on when pressure reaches an acceptable level.)

If everything else is good for sure.... then...

If you wanna see if the compressor is getting signal. unplug it and take a multi meter to the connector and test for an output on the connector. if your getting signal blame the compressor.

If you not getting any output from the connector then you would need to go ahead and check everything else.

Ive had an issue with mine for years. it takes a bit of driving for the compressor to start doing its job. I know its the compressor clutch not doing its job.

connector pin out for reference. its a 2 wire plug, 1 is power, other is ground. measure voltage output here.
 

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