A/C Compressor "Clunk"

[masterstream]

Is anyone experiencing a noticeable clunk when their A/C compressor engages for the first time after the truck has not been used for several days? Aside from the noise, it makes the engine stumble as if it is struggling to spin the compressor. After the first time, all other engagements seem fine. Thanks.

 

[SierraRam]

Yes, scares the crap out of you doesn't it Like you say only seens to happen if you haven't use it for a while.



SR

 

[DZLFREK]

From what I've been told this is "normal" for our trucks.



David

 

[p-Bar]

Most do it, no worries

 

[JCasper]

Most do it, no worries

Yep, mine does it also

 

[masterstream]

Thanks for the input. I'm glad it's not an isolated condition. It's a terrible noise; sounds like the compressor is going to be torn from its bracket.

 

[EArp]

Mine does it too. First time I noticed it was right after I had done my "home depot" cold air induction kit and I thought I had left a tool laying around under the hood and it fell into the motor!! Scared the "you know what" outta me!

 

[JMusso]

I always wondered what that was. It has only happened a couple times. Hard to believe it's "normal".

 

[LRutigliano]

My truck does it too. Its very loud and it sounds like something broke when you first engage the AC.



However, its normal... and its most prevalent after the truck has not been started for awhile.



It due to compressor slugging... liquid refrigerant (and oil) trying to be compressed upon initial start up of the compressor.



On our trucks, the AC compressor is at the lowest point or very close to the lowest point in the system. The refrigerant condenses in the lowest point of the AC system (the compressor in our case).



Once the system is started, the whole phase change (low pressure gas to high pressure gas to high pressure liquid to low pressure liquid back to low pressure gas) process takes over.



The Sanden compressor is pretty tolerant of this occurance.



Hope this helps,

Louis

 

[Regcabguy]

Thanks Louis for the explanation. Sometimes mine is nearly silent,othertimes,"CLUNK".

 

[LRutigliano]

Sometimes mine is nearly silent,othertimes,"CLUNK".

Good point that I forgot to mention:



Mine also does this only sometimes. (its not my daily driver)



If I'm on a camping trip and have been using the truck regularly, then it doesn't happen.



However, if I let the truck sit in the garage for some time (days) and then start the engine and AC compressor, I get a loud CLUNK because the refrigerant has had time to migrate into the compressor and has had time to condense.

 

[MZuba]

Mine does it also, and when I inquired from the dealer they wanted to change the compressor, not under warranty of course, so I did some checking and found out it was "normal".

 

[ABarry]

Mine (06) has done it from the day I got it.

 

[SHobbs]

Clunking since day one.

 

[Garlic]

Mine does too, scare the begeebers out of my wife the first time she heard it. (Thank goodness she does not have the begeebers any more)

 

[KEpperly]

both of my trucks have done it. dealer says its normal.