A/C compressor not turning off?

gpjlytham

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ARIZONA
Hi All

My A/C works great on the freeway but not so great sat at a stop light, so I opened the hood to look to see if the compressor is turning on or off and it is ALWAYS ON?

The radiator fan appears to be working fine and moving lots of air. The radiator doesn't appear to be blocked but I haven't taken it out, i've only looked at it.

I attached some gauges and i got the following readings: -
Engine turned off both high and low are at 125
with the engine running the readings are 175 and 42 they change very slightly but basically they stay the same.

what's going on? low on refrigerant? too much refrigerant? expansion valve not working correctly? compressor going bad? pressure sensor not working?

I lost my job due to the pandemic so i'm not looking to spend too much but it would be nice to be more comfortable when i'm sat at the traffic lights.

Any help would be appreciated.
 

Kraig Wilkinson

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Kraig Wilkinson

SUPPORTING MEMBER
SUSTAINING MEMBER
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New Jersey now live in South Dakota
2G Genesis Sedan (2015-2016)

gpjlytham

Hasn't posted much yet...
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ARIZONA
Anther thought: -

The compressor is always on so you would think it would get so cold that ice would be forming on the pipes but that isn't happening.
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jimmy buoy

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Sarnia, Ontario, Canada
2G Genesis Sedan (2015-2016)
I had read on an old post that the A/C compressor on the Genesis doesn't utilize a conventional on/off clutch like most vehicles. Not sure how it actually varies the pressurization of the refrigerant but it seems to do the job just fine. I've had 4 different Genesis sedans and have never heard or felt the compressor clutch engage/disengage like all the other vehicles I've owned. It is nice NOT to hear the clutch engage and the revs suddenly increase like a typical unit.
 

Kraig Wilkinson

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jimmy buoy

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Sarnia, Ontario, Canada
2G Genesis Sedan (2015-2016)
They use what is called a squash block. Like little piston and they can very the pressure by changing the angle of block that pistons push against. Something to that effect. They make some hydraulic pump that way,.
Thanks for the clarification - I knew it was something complicated like that. At least we don't have to worry about failed clutches on our A/C!
 

gpjlytham

Hasn't posted much yet...
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ARIZONA
I thought that they all cycled on and off, so its good to know that the clutch is supposed to be always engaged. but i'm still having the issue of significantly warmer a/c at stop lights compared with driving on the freeway. I assume that there are specs for the a/c pressure does anyone have a chart? one that would include Phoenix hot temps with little humidity.
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Kraig Wilkinson

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joegr

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Freon is a Dupont brand name for some older refrigerants. I believe the refrigerant used in these cars is R-134a, which has a brand name of Suva. It's really best to refer to it as the generic "refrigerant."
You can't correctly charge refrigerant just by looking at low side pressures (DIY can with a gauge). You have to look at the low and the high sides and compare it to the correct temperature/pressure charts. Even then, your odds of getting the charge just right are not great. It's far better to completely evacuate and then refill by weight. These cars are way more particular about having the exactly correct amount of refrigerant than other cars I have maintained.
Of course, it may not be low refrigerant. The valve that controls the compressor (instead of having a clutch) seems to not be an uncommon failure, and said failure seems to often have the symptom of poor cooling at idle. (I have also seen symptoms of not working at all, or of there being a delay before the cooling starts.)
If you add refrigerant and the problem was not low refrigerant, you could cause damage that will greatly increase the final repair cost...
 

Kraig Wilkinson

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pulsar

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I’m not sure we use R134 still? My 2020 has a sticker under the hood that I think said R1234. Not sure the difference or if the sticker is a typo? Did not realize our clutches did not cycle either? The compressor and pistons being described does sound like a wabble type of pump similar to some hydraulic pumps and how the piston stroke can change. I just wish my recirculate function in the afternoons stayed on more than 3 or 4 minutes at a time.
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EdP

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pulsar

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Good catch. 1234yf is the future of refrigerants. Just looked and my 2018 G80 has it. Charge is about 1.4 lb at $100 a pound!

Found this:
R-134a was originally the replacement for R-12 which was phased out when it was found to be harmful to the ozone layer. Years later, R-134a was found to contribute to global warming, and now it too is being phased out . Enter R-1234yf. R-134a and R-1234yf do have many similar properties. That’s because R-134a is a hydrofluorocarbon (HFC) while R-1234yf is a hydrofluoro-olefin (HFO) refrigerant. Both are composed of hydrogen, fluorine and carbon atoms. However, there are notable differences between the two refrigerants as well. While R-134a has a Global Warming Potential of 1300, R-1234yf’s GWP is less than 1
Good to know and thanks for the education on the Freon differences for I have never looked that up. Guess I can add my full can of R134 to go alongside with the 5 cans of R12 I still have. I could start a museum with obsolete Freons. I should have sold my R12 cans years ago when the price skyrocketed for not even sure its legal to possess that these days?
 

EdP

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Kraig Wilkinson

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joegr

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No Genesis Yet!
I’m not sure we use R134 still? My 2020 has a sticker under the hood that I think said R1234. ...
I'm sorry. I assumed that the OP's car was a 2009-2014 (since this is under that section). Up to 2014 should still be R-134a. I know that my 2015 Cadenza is. I am aware that cars have moved on from that in the last few years.
 

pulsar

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Video was a good rant for had no idea what the cost of this new Freon was or that it was flammable? Obviously with cost and pressure changes the govt is pushing your DIY garage mechanic to the dealer now. Not sure what pressures my older gages even go up to? I can remember way back when a can of R12 at the local hardware store was just $1.19. Simpler times for sure.
 

EdP

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