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Discussion Starter #1
Folks,

I had a lot of issues last year with my 2005 santa fe AC...First was the fan connector which the dealer cleaned up then after four trips to the dealer to fix a leak they finally replaced the compressor. It ran fine for the next two months then the cold weather came. We had a 73 degree day a few weeks ago so I decided to test the AC....Nothing....Its as if the AC button which lights up does not turn on the AC. I checked the 10amp AC fuse near the relays under the hood and there is no voltage there with switch on or off...I would think the button to turn on AC is bad although the little green light comes on..Is there anything else that triggers that 10 amp fuse location to get 12v? Any other ideas.....I hear there may be another fuse in the passenger location but cannot find it yet...

Any help would be greatly appreciated as I have another dealer appt on Friday and if it is the AC button I will buy one and replace myself..

Thanks, Tony
 

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I checked the 10amp AC fuse near the relays under the hood and there is no voltage there with switch on or off...I would think the button to turn on AC is bad although the little green light comes on.
Hi Tony.

No it doesn't sound like your AC switch is bad. The AC fuse under the hood is the fuse that supplies power to the compressor clutch relay. If there's no 12V supply to the fuse the AC compressor wont run so the AC can't work. There should be a constant 12V supply to the AC fuse. If the blower motor is working OK but there isn't any voltage being supplied to the AC fuse, that suggests there's a fault inside the fusebox.

Regards.
Scottie.
 

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Discussion Starter #4
Scottie, Is there another place air should look to troubleshoot? nobody touched the fuse boxes recently and everything looked ok visually...What does the actual ac button supply power to....I figured when I hit the bottom the 10amp fuse would then get power. similar to the other fuses like the fog lights and such...
 

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Like the guy says, check to see if the freon is up to capacity. NOTHING will work if there is no freon in the system.
 

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What does the actual ac button supply power to....I figured when I hit the bottom the 10amp fuse would then get power. similar to the other fuses like the fog lights and such...
No, that's not how it works. There should be a constant 12V supply to the AC compressor relay via the AC fuse. If there is no voltage being supplied to the AC fuse the compressor can't operate, regardless of what the freon pressure is. Also, the compressor isn't directly controlled by the AC switch. It's controlled by the engine PCM.

A quick and dirty test you could try as a temporary measure to confirm the rest of the system is working is use a link wire to bridge the AC relay to battery positive....see below. If that gets the AC working then you know you have a problem inside the fusebox.

 

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Yes it is how ANY A/C system works. All rhetoric aside, why on earth would you even consider chasing circuits, fuses, and imaginary faults around, spending lots of time. if YOU DON'T EVEN KNOW IF THE SYSTEM HAS A FULL CHARGE OR NOT? Let the guy with the problem speak here, and say if the system has a full charge in it. And not from last year, now with the gauges on it. Don't worry about checking anything until the system is EVACUATED, and CHARGED fully to spec first.
 

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There are 7 fuses related to the A/C
6 can be found in the engine bay compartment (4 fusible links, 2 ten amp fuses)
One of which is related to the A/C compressor through the compressor relay
That fuse should be hot at all times (12 volts all the time, car or A/C on or off) as Autospark says.
Listen to him (A/C doesn't need a full charge to check that fuse)
He knows how to by pass that pressure switch if need be

1 (the 7th) fuse can be found in the dash fuse box (ten amp)
It supplies power to the interior A/C switch with illumination (illumination and A/C switch are separate)
That switch then sends a signal to the thermostatic switch (thermistor)
which then goes to the A/C pressure switch (open below 29 psi or open above 455 psi)
which then goes to the ECU to tell it to turn on the A/C compressor

Troubleshooting requires patience and knowledge of the system
Good luck

Note: We chase circuits because of who we are.
A fireman chases fire. A policeman chases crooks.
An electrician chases circuit faults.
 

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There are 7 fuses related to the A/C
6 can be found in the engine bay compartment (4 fusible links, 2 ten amp fuses)
One of which is related to the A/C compressor through the compressor relay
That fuse should be hot at all times (12 volts all the time, car or A/C on or off) as Autospark says.
Listen to him (A/C doesn't need a full charge to check that fuse)
He knows how to by pass that pressure switch if need be

1 (the 7th) fuse can be found in the dash fuse box (ten amp)
It supplies power to the interior A/C switch with illumination (illumination and A/C switch are separate)
That switch then sends a signal to the thermostatic switch (thermistor)
which then goes to the A/C pressure switch (open below 29 psi or open above 455 psi)
which then goes to the ECU to tell it to turn on the A/C compressor
Was there nothing good on the telly last night, so you just read the Santa Fe trouble shooting manual :laugh:

avisitor said:
Note: We chase circuits because of who we are.
Well, I just like to start off by fixing the faults I can physically see, like a fuse having no power when it should. Someone posted on another thread just the other day saying their AC wasn't working and I suggested to that person they have the gas pressures checked. If having the pressure checked makes sense I would suggest it. The OP in this thread has identified a problem that will stop his AC from working, so in this case I think fixing the fault that has already been identified is a great first step. Some folk obviously have a different opinion, and that's OK. One things for sure though, the AC ain't gonna work if there isn't any power being supplied to the compressor, regardless of how much freon is in the system.
 

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Discussion Starter #11
Ok guys....I took the truck back to the dealer for the 5th time overall. They said the feon was gone. They charged it back up and added the dye and sent me on my way. This time I decided to find the link that eluded the dealer. I found it in 10 mins. Its a slight leak near the low side port into the firewall. I am pretty sure there is an o-ring at that connection after the allen key screws are removed. Now, I need to fight with the dealer as they banged me for a compressor I am sure I did not need. I hope they don't try to tell me I need a new hose\pipe as the leak is at the connection....I will take pics tonight...I appreciate all the help so far...

Tony
 

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AC PRESSURE SWITCH, THERMISTOR, CLUTCH, ETC.; Could someone post an electrical schematic of the entire AC system... I'm working on two cars with inop AC....2004 Santa Fe (pressure switch 4 pin connector) & 2007 Sonata (pressure switch 3 pin connector)
 

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There are different AC systems fitted to Hyundai cars which will either have manual or auto (digital) control panels. So you'd need to tell us which system your working with before someone could post the schematic.
 

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Sorry about that....both cars have the manual controls....I did receive the Santa Fe diagrams but would really appreciate it if someone could help me with the Sonada diagrams... in fact, another user sent me the workshop manual along with the diagrams... very helpful!
 
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