A/C blows hot when idling
June 24th, 2022, 8:19 PM
#1
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A/C blows hot when idling
Hey guys,
I'm a newbie to the Chevy forums. I have a 2017 2500 Express van that blows hot when at an idle. It only does this when it's borderline hot outside. If I'm at highway speeds it eventually starts blowing cold and will freeze you but when I stop and allow it to idle it'll start blowing hot within minutes. Like I said, it only does this when it's hot outside but if the weather is warm (not hot) this issue doesn't occur. I can hear and feel the compressor clutch kick in when I first turn it on but when it's hot I can't feel or hear anything, other than me crying about it. I had a guy put gauges on it and he said everything is where it should be. He suggested that the relay is possibly overheating and won't allow the compressor to turn on. What else can I look at?
I'm a newbie to the Chevy forums. I have a 2017 2500 Express van that blows hot when at an idle. It only does this when it's borderline hot outside. If I'm at highway speeds it eventually starts blowing cold and will freeze you but when I stop and allow it to idle it'll start blowing hot within minutes. Like I said, it only does this when it's hot outside but if the weather is warm (not hot) this issue doesn't occur. I can hear and feel the compressor clutch kick in when I first turn it on but when it's hot I can't feel or hear anything, other than me crying about it. I had a guy put gauges on it and he said everything is where it should be. He suggested that the relay is possibly overheating and won't allow the compressor to turn on. What else can I look at?
June 25th, 2022, 1:27 AM
#2
CF Monarch
Hey guys,
I'm a newbie to the Chevy forums. I have a 2017 2500 Express van that blows hot when at an idle. It only does this when it's borderline hot outside. If I'm at highway speeds it eventually starts blowing cold and will freeze you but when I stop and allow it to idle it'll start blowing hot within minutes. Like I said, it only does this when it's hot outside but if the weather is warm (not hot) this issue doesn't occur. I can hear and feel the compressor clutch kick in when I first turn it on but when it's hot I can't feel or hear anything, other than me crying about it. I had a guy put gauges on it and he said everything is where it should be. He suggested that the relay is possibly overheating and won't allow the compressor to turn on. What else can I look at?
I'm a newbie to the Chevy forums. I have a 2017 2500 Express van that blows hot when at an idle. It only does this when it's borderline hot outside. If I'm at highway speeds it eventually starts blowing cold and will freeze you but when I stop and allow it to idle it'll start blowing hot within minutes. Like I said, it only does this when it's hot outside but if the weather is warm (not hot) this issue doesn't occur. I can hear and feel the compressor clutch kick in when I first turn it on but when it's hot I can't feel or hear anything, other than me crying about it. I had a guy put gauges on it and he said everything is where it should be. He suggested that the relay is possibly overheating and won't allow the compressor to turn on. What else can I look at?
June 25th, 2022, 5:47 AM
#3
CF Junior Member
I'm not a huge Chevy expert but this is kind of standard. Check to see if the radiator cooling fans are working. Sounds funny but those fans also cool the AC condenser. When the vehicle stops moving the condenser overheats and can't dissipate the heat. When you start moving the airflow cools it and you eventually have AC again. This will happen faster than the engine overheating and just one faulty fan can cause it.
It's easy enough to check. If you idle it with the AC on the cooling fans should kick on after a few seconds regardless of engine temp. If they don't turn on you've found your problem. The fans themselves can fail as well as the relay that powers them.
It's easy enough to check. If you idle it with the AC on the cooling fans should kick on after a few seconds regardless of engine temp. If they don't turn on you've found your problem. The fans themselves can fail as well as the relay that powers them.
Last edited by Derrick71; June 25th, 2022 at 5:50 AM.
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oilcanhenry (June 25th, 2022)
June 25th, 2022, 7:02 AM
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June 25th, 2022, 7:04 AM
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I'm not a huge Chevy expert but this is kind of standard. Check to see if the radiator cooling fans are working. Sounds funny but those fans also cool the AC condenser. When the vehicle stops moving the condenser overheats and can't dissipate the heat. When you start moving the airflow cools it and you eventually have AC again. This will happen faster than the engine overheating and just one faulty fan can cause it.
It's easy enough to check. If you idle it with the AC on the cooling fans should kick on after a few seconds regardless of engine temp. If they don't turn on you've found your problem. The fans themselves can fail as well as the relay that powers them.
It's easy enough to check. If you idle it with the AC on the cooling fans should kick on after a few seconds regardless of engine temp. If they don't turn on you've found your problem. The fans themselves can fail as well as the relay that powers them.
June 27th, 2022, 1:14 AM
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June 27th, 2022, 8:56 PM
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So today I had the chance to check things out. When it starts blowing hot the compressor clutch is not engaging at all. Usually at highway speeds it'll kick in and begin to cool off but today was a different story. It wouldn't blow cold no matter what. The guy who checked the system with the gauges a few weeks ago showed me the compressor engaging intermittently but it wouldn't do it when the engine got hot. Today, the radiator fan was on but the nothing i could do would engage the clutch.
June 27th, 2022, 9:40 PM
#9
CF Junior Member
When the magnetic clutch refuse to engage what is the engine temperature gauge read ?
Even if the radiator fans kicks in... it could be a defective coolant thermostat or a defective water pump.
You must be shure the engine is not overheating.
There is a possibility that the PCM cancel your A/C if it reads correctly or incorrectly a high engine temp.
Here
Even if the radiator fans kicks in... it could be a defective coolant thermostat or a defective water pump.
You must be shure the engine is not overheating.
There is a possibility that the PCM cancel your A/C if it reads correctly or incorrectly a high engine temp.
Here
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oilcanhenry (June 28th, 2022)
June 28th, 2022, 2:44 AM
#10
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So today I had the chance to check things out. When it starts blowing hot the compressor clutch is not engaging at all. Usually at highway speeds it'll kick in and begin to cool off but today was a different story. It wouldn't blow cold no matter what. The guy who checked the system with the gauges a few weeks ago showed me the compressor engaging intermittently but it wouldn't do it when the engine got hot. Today, the radiator fan was on but the nothing i could do would engage the clutch.
When I was in junior college specializing in auto-airconditioning this chick had something blow out, like an explosion (likely allowed HP into the LP system). and her face took some shrapnel, but thankfully not an eye. Never saw her after that incident, and the teacher would not speak of it, likely fearing a lawsuit.