Ac Compressor

[Paradigm49]

Quick question. I have a 2010 Chevy Silverado LT, 6.2, just turned 23,000 miles on it.

 

 

 

Two things are concerning me. One of them being is that about every 25-30 seconds the AC compressor is kicking on, even if the AC isn't on...and it's not subtle about it, it is a very noticable clunk when the clutch engages. Is that normal?....i've never noticed it until about a week ago, took it to the dealer and they said it was normal.

 

 

The other thing i am noticing is that if I'm sitting idle or have the truck parked and the hood open, it feels like i have a misfire from the vibration i'm getting from the engine. So much so that the dipstick for the Transmission is vibrating (i would say a good 3/4's of an inch in either direction) and my antenna vibrates...but i haven't lost any gas mileage and i am not getting any codes..

 

 

 

I have tried pulling and reseating all of the coils and plug wires..both when the truck is on and off (which may not have been intelligent on the while it's on part) but that defintely showed what it would run like if there was a dead cylinder..and the engine vibration isn't that distinct as compared to when i disconnect a sparkplug.

 

 

 

 

I don't typically take my vehicle to the dealer unless i have to but just wondering if anyone had any ideas or thoughts,

 

 

Greatly appreciated!

 

 

 

 

 

Thanks!

[ChevyTech77]

You say the a/c isn't on but is the hvac controls set for defrost? That will turn on the a/c compressor as well.

 

My 6.2 doesn't idle the smoothest either, hasn't sense I got it with 212 miles on it. I'd say it's the nature of the beast especially considering how you don't have an ses light coming on or no dtc setting in the ecm.

[Paradigm49]

rear defrost or the front defrost...and yes...it is...Upstate NY here, it's usually a tad chilly in the mornings here--not too bad this week but that will change. Should i try it on a non-front window defrost setting and see if it does the same?---that never crossed my mind---though really i wouldn't figure having the heat and defrost on to kick the AC compressor on...

 

 

 

And no, the 6.2 does NOT idle smooth....the 5.3 and the 6.0 i had in my 2007 sierra were a bit smoother, but....considering the compression ratio and the VVT, i didn't know if it was normal to have that much vibration going.

 

 

 

Thanks for the ideas, i will defintely check into them.

 

 

 

 

 

You say the a/c isn't on but is the hvac controls set for defrost? That will turn on the a/c compressor as well.

 

My 6.2 doesn't idle the smoothest either, hasn't sense I got it with 212 miles on it. I'd say it's the nature of the beast especially considering how you don't have an ses light coming on or no dtc setting in the ecm.

[ChevyTech77]

rear defrost or the front defrost...and yes...it is...Upstate NY here, it's usually a tad chilly in the mornings here--not too bad this week but that will change. Should i try it on a non-front window defrost setting and see if it does the same?---that never crossed my mind---though really i wouldn't figure having the heat and defrost on to kick the AC compressor on...

 

 

 

And no, the 6.2 does NOT idle smooth....the 5.3 and the 6.0 i had in my 2007 sierra were a bit smoother, but....considering the compression ratio and the VVT, i didn't know if it was normal to have that much vibration going.

 

 

 

Thanks for the ideas, i will defintely check into them.

 

Defrost not defogger. Rear window = defogger, Front window = defrost.

 

The a/c compressor has been run with the hvac controls in the defrost setting sense the mid 70's for two reasons...

1. To facilitate getting rid of the moisture that is evaporated off the window by heat

2. To run the a/c compressor some during it's normal off season (defrost is used all winter) to keep oil circulating in the system.

 

Totally normal for it to run. Once we start getting below about 30 ish degrees all the time, it will stop running altogether to keep from freezing up the evaporator core. It will cycle more than usual in the colder temps than it

did during the summer and unless the compressor is loose in it's mounting, the thump noise associated with it coming on is for the most part, normal.

 

6.2 rough idle and HP or 5.3 smooth idle and 100 less hp? I know which one that I picked besides, almost reminds me of my '86 K-30 with the 406 small block that I built for it idling rough because of the cam that was in it. I'm good with it.

[Paradigm49]

Don't mind me, I've been up for about 60 hours straight (I do IT for a living, have been dealing with some server issues so...needless to say i'm a little loopy at the moment)...thankfully things are finally fixed...my sanity..thats another question.

 

 

 

I just wasn't totally sure what the thump was from, originally i thought it was the fan clutch kicking in on the two fans in the front of the truck but when i sat and looked and noticed the fans were spinning i thought it was rather odd...then just sat there and looked at the engine and noticed it was the AC. I can completly understand the reasons for it coming on and off...just didn't think it would be THAT pronounced...Honestly it's at the same noise level of the slip yoke clunk if that puts it into perspective.

 

 

 

As for the slightly rough idle and 100 more horsepower than the 5.3?...yeah i can deal with that too...i just wanted to make sure i wasn't the only one that had a 6.2 that was doing it.

 

 

 

Thanks for your help!

 

 

 

rear defrost or the front defrost...and yes...it is...Upstate NY here, it's usually a tad chilly in the mornings here--not too bad this week but that will change. Should i try it on a non-front window defrost setting and see if it does the same?---that never crossed my mind---though really i wouldn't figure having the heat and defrost on to kick the AC compressor on...

 

 

 

And no, the 6.2 does NOT idle smooth....the 5.3 and the 6.0 i had in my 2007 sierra were a bit smoother, but....considering the compression ratio and the VVT, i didn't know if it was normal to have that much vibration going.

 

 

 

Thanks for the ideas, i will defintely check into them.

 

Defrost not defogger. Rear window = defogger, Front window = defrost.

 

The a/c compressor has been run with the hvac controls in the defrost setting sense the mid 70's for two reasons...

1. To facilitate getting rid of the moisture that is evaporated off the window by heat

2. To run the a/c compressor some during it's normal off season (defrost is used all winter) to keep oil circulating in the system.

 

Totally normal for it to run. Once we start getting below about 30 ish degrees all the time, it will stop running altogether to keep from freezing up the evaporator core. It will cycle more than usual in the colder temps than it

did during the summer and unless the compressor is loose in it's mounting, the thump noise associated with it coming on is for the most part, normal.

 

6.2 rough idle and HP or 5.3 smooth idle and 100 less hp? I know which one that I picked besides, almost reminds me of my '86 K-30 with the 406 small block that I built for it idling rough because of the cam that was in it. I'm good with it.

 

[Jsdirt]

I have the 5.3, & it's done both those things since it was new. The shake got more pronounced as it broke in, & has done it since. It's a wonder it doesn't throw a misfire code ... because when my carbureted vehicles behave this way, I start checking timing & making carburetor adjustments. I have owned 40 year old vehicles that didn't shake (or have interior squeaks ...) as bad as my '07.

 

Funny how back in the 70's A/C systems worked better & were more quiet. How a bang-on / bang-off system is better than one that runs continuously is beyond me ..... but hey, progress right?

[Paradigm49]

So they say.....progress that is....

 

 

 

 

 

I have the 5.3, & it's done both those things since it was new. The shake got more pronounced as it broke in, & has done it since. It's a wonder it doesn't throw a misfire code ... because when my carbureted vehicles behave this way, I start checking timing & making carburetor adjustments. I have owned 40 year old vehicles that didn't shake (or have interior squeaks ...) as bad as my '07.

 

Funny how back in the 70's A/C systems worked better & were more quiet. How a bang-on / bang-off system is better than one that runs continuously is beyond me ..... but hey, progress right?