AC Compressor not working

[rrkazman]

A few weeks ago my AC stopped working, so I thought I would check out what was going on. I found the connection going to the Compressor was cut it had come in contact with the serpentine belt and had shorted the leads together. I repaired that but the compressor still will not come on. I started looking for blown fuses, and found that there is an AC control module which has 5 fuses. All good. All of the voltage sources that are to be constant and cycle with the ignition are all correct. Since this seemed to be more than I wanted to handle, I took to the master Hyundai mechanic in the area. He confirmed what I had though that the AC control module must be bad. These are not being made right now because of the chip shortage, so I purchased a referb unit. I had the mechanic install the module. Same problem no AC compressor. The Hyundai has said it cannot be repaired and all parts of the system should be replaced, that would be 20K if the parts were available. The system is full of gas, and the compressor will run if 12 Volts are applied to it directly. I am looking for other possibilities like the compressor cut signal that come from the ECM. I cannot find out any thing about that signal. While the AC control module is the one connected to the compressor, the ECM generates AC SELECT Switch, AC REQUEST Switch, and AC Compressor Cut signal. There is a chance that both of the AC Control Modules are bad, I think that is unlikely. Is there any one who knows about these signals and there values during the operation of the AC system?

 

[G-180115]

Hi everyone im new here , i have a 2010 Hyundai Genesis 3.8 v6 a/c compressor not working properly was told by a mechanic i need a new compressor , but it cools the car if im driving but im sitting in one spot it wont blow cool , it works at night s too because its cooler .Does anyone has that problem too?needed a second opinion, was told that the compressor is always spinning while the car is on and not when the a/c get turned on .

 

[rrkazman]

Hi everyone im new here , i have a 2010 Hyundai Genesis 3.8 v6 a/c compressor not working properly was told by a mechanic i need a new compressor , but it cools the car if im driving but im sitting in one spot it wont blow cool , it works at night s too because its cooler .Does anyone has that problem too?needed a second opinion, was told that the compressor is always spinning while the car is on and not when the a/c get turned on .

You very well need a new compressor, I had exactly the same issue a couple of years ago, and had to have the compressor replaced. Unfortunately they will have to replace all of the major components in the system. Mine was covered under warranty so I don't know what it cost. You might want to take it to another shop, but my symptom was the same when it was the right temperature outside it worked but other times it did not work at all.

 

[EdP]

The system is full of gas, and the compressor will run if 12 Volts are applied to it directly.

I know what I would do. No way would I spend 20k for repair. If, in fact, it runs with 12vold applied I'd rig up a direct wire and a manual switch in the cabin. Yes, half assed but $10 instead of $20k and the AC cools the air.

I've done worse in a couple of cars.

 

[rrkazman]

I have thought of that how ever while the car is in normal operation there are a series of sensors that control the compressor on and off. The most important of these in the Freon pressure sensor, the computer uses the pressure to determine the temperature of the system. It will cut off the compressor when needed of safety requirements. Without this the system can go into over pressure and vent Freon through the safety over pressure valve. In the worst case it will blow the expansion valve and vent all the Freon into the passenger cabin. What I want to do is track down the actual problem and replace the offending component. The dealer will not do that it takes to much time an energy, and more than a rudimentary knowledge of electricity. I have a leg up there I am 40 years an electrical engineer, with considerable experience in industrial HVAC. The hard part here is understanding the signals from the ECM to the AC Control module, and being sure that the pin layouts for the various plugs are what you think it is. In this model year there are 3 models, they share a wiring diagram but some sections are labeled for the 3.8, and alternately for the 4.6 and the 5.0. They have some car specific plugs. Thank you for the thought

 

[Charlie1982]

Hi everyone im new here , i have a 2010 Hyundai Genesis 3.8 v6 a/c compressor not working properly was told by a mechanic i need a new compressor , but it cools the car if im driving but im sitting in one spot it wont blow cool , it works at night s too because its cooler .Does anyone has that problem too?needed a second opinion, was told that the compressor is always spinning while the car is on and not when the a/c get turned on .

Could easily be a failed compressor. I had to have my compressor replaced this last summer, it was leaking. I normally do most of my own work, but I don't have A/C equipment, so I had this done for me at a local independent shop. They said the new compressor was updated from the original one, so hopefully it'll last longer.

 

[Charlie1982]

I have thought of that how ever while the car is in normal operation there are a series of sensors that control the compressor on and off. The most important of these in the Freon pressure sensor, the computer uses the pressure to determine the temperature of the system. It will cut off the compressor when needed of safety requirements. Without this the system can go into over pressure and vent Freon through the safety over pressure valve. In the worst case it will blow the expansion valve and vent all the Freon into the passenger cabin. What I want to do is track down the actual problem and replace the offending component. The dealer will not do that it takes to much time an energy, and more than a rudimentary knowledge of electricity. I have a leg up there I am 40 years an electrical engineer, with considerable experience in industrial HVAC. The hard part here is understanding the signals from the ECM to the AC Control module, and being sure that the pin layouts for the various plugs are what you think it is. In this model year there are 3 models, they share a wiring diagram but some sections are labeled for the 3.8, and alternately for the 4.6 and the 5.0. They have some car specific plugs. Thank you for the thought

You'll need to track down the service manual (not just the owner's manual) for information like that. Sounds to me like you could probably do the work, if you can get the right info.

 

[rrkazman]

I have tracked down much information, two verified wiring diagrams, one with pictures of the location of all of the modules. I have not had time to work on it but I will today. I will post what I find.

 

[rrkazman]

If anyone is still following this feed, I resolved the AC issue but it took some doing. I had to build some special test connectors that allowed me to get a digital meter connected to the Temperature control module under the dash to verify that the command voltage to the compressor was being sent when it should be. What I did find through testing is that the voltage is not constant, and it is not 12 Volts. The max voltage is 10 volts, but the voltage is variable, it can go down to 3 volts during operation. The compressor does not have a magnetic clutch, it has a variable displacement system. This allows the load of the compressor to be reduced as needed. This added to the confusion about what was wrong with the system. In the end I had both a bad control module, and a failed compressor. I replaced the compressor and recharged the system and it worked fine. I did have the first replacement compressor fail when the centrifugal clutch came apart. The centrifugal clutch, is designed to allow the engine to start without the compressor engaged. Once the engine starts the compressor is always turning, it may have a reduced output by command but it never stops turning.

 

[G-123452]

HELP!! I have a similar issue with my 2010 genesis only my problem is the darn thing will not turn on when I hit the power button. I have to just leave it turned on and hope that somewhere along the way it will decide to turn on. Once it does, (if it does) , then all the controls work great. I can turn fan up and down change temp and change from vent to defrost or whatever. If it does finally turn on then I can not kill my car because if I do it will be the same thing it will not turn on... What can be the cause of this? Also I can turn it off with the power button when it finally comes on... Someone please help me with this because the heater is the same way.

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