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Discussion Starter · #1 ·
I have a 2012 elantra, my wife told me this week the blower is not blowing cold air. Finally got around to checking it today,

After a little bit of troubleshooting i found the issue to be at the compressor. No voltage was being sent to the compressor. Checked fuses anything that said a/c, all were okay under the hood and in cab compartment. Checked clutch with a variable power supply, clutch fired!

Next, i started vehicle and ran a/c on max, wondering if there was maybe a freon leak or an evap issue and maybe my ecg was telling my clutch not to engage because of this. So i engaged my clutch manually, and was blowing ice cold air almost instantly, ran it for 4-5 minutes, no issues what so ever! My wife had been trying to run the a/c all week.

Any ideas what could be telling my clutch not to engage? Im guessing i have a faulty sensor some-where. Really dont want to take it to dealership.

Im leaning towards an evap sensor, with the temp control to max a/c i get warm air 32C, if i come off max cold i get hot air. when i manually engaded clutch i think i got like some 12-13degrees.

Thanks!
 

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Discussion Starter · #2 ·
sorry looked at it again this morning, I'm assuming my issue may be a Freon issue, where the pressure is too low, but I can't get my buddies gauges until mid-week to measure. At the pressure switch, I have a 3 wire connector, ground, signal, 5v, is there a way I can jumper this. On the harness I have two blue/white wires and I think a black, if I short the 2 blue/white wires on the actual harness, will this send 5v back and hopefully fire my compressor?


- Then if that works, and I measure my levels and they check out, I know that pressure switch is toast.
 

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Yeah, just go out and get a can of freon with the little gauge on it. It will indicate low freon when you hook it up, then you can add as needed.
 

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Plug into DLC, and look at current data for A/C in the PCM.. pressure sensor will reflect pressure in the system,, to which if too low, it'll prevent PCM from allowing compressor to run

System off and equalized, need to see 70+ psi for system to turn on.... OR,, you can wait for gauge set and manual inspect system pressure

Another question that need to be answered, is your compressor a 3 wire connector with blue / red-orange / black wire in connector,,,, or is it a (1) wire connector with orange wire

If 3 wire, it has an ECV inside compressor,, and there is SST use to test the valve in the compressor (required if we need to warranty a compressor as part of diag to verify ECV is actual fault, then we replace compressor
 

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actual compressor in a 1 wire, the pressure sensor is a 3 wire.
Gauge it, or Data stream it for static system pressure.. unplug compressor and check for 12V with engine idle and HVAC set to A/C (MAX) help keep it so you can inspect..

Go to engine room junction box.. DVOM both leg of A/CON fuse (red 10A) for voltage on both leg..

Remove A/C relay.. find terminal that carry out to compressor,, while compressor plug in, we going to check resistance between relay terminal though field coil to ground (find if coil open / short / or too high resistance)
 

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Discussion Starter · #7 ·
No 12v to compressor with harness off and full a/c on. i have 12v on one leg of the fuse but not pulling any current. fuse is fine. Im assuming power is going from the fuse and to the pressure sensor and then heading to the compressor. There is no relay designated for anything a/c only blowers, and my blowers are working normal. my scanner is not capable of reading too many features on hyundai models.

i've already confirmed the compressor and clutch are fine, there is 'some' freon in the system as im blowing cold air when i override with power supply. Its either the pressure switch is faulted or my freon is low. Thats why i was looking to try and confirm if there was a way i could override from the pressure switch, that way i can compare it to my freon reading to determine who the culprit is. With any luck i can override this pressure switch somehow and my a/c should kick on then i have confirmed as much as possible without getting my gauges on.
 

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PCM closes A/C relay to allow source voltage to drive clutch

Pressure sensor tells PCM if we have sufficient R134 pressure to allow system operation
 

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Discussion Starter · #9 ·
There is no a/c relay that i can find only fuses. If what your saying is true then my ecm is telling my a/c not to turn on, and my problem is upstream of both the pressure switch and compressor.
 
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