Having a "pop" sound when i start my car

[Burnsy]

it's one of the clutches engaging, it's normal. if you haven't heard it you probably just didn't hear it, or it is quieter in your car, but it is normal

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[stang910]

I think what your hearing is the A/C compressor kicking in. Mine just started doing it a few weeks ago. I believe theres a tsb on this not 100% sure. To me what it feels and sounds like is someone taking a hammer and hitting the engine. Hopefully it doesn't affect the life of the compressor cause it really doesn't bother me since it doesn't do it all the time.

[Nuke]

Unless you're accidently leaving the A/C or the front defrosters on, why would the compressor kick on when you start the car? Mine doesn't come on on start-up.

[Cobrakev]

The A/C is automatically cut out during engine start.

[turbotbirdguy79]

I think what your hearing is completly normal.Its called CASS.Liquid refrigerant may accumulate in the A/C compressor under certain conditions. To alleviate damage to the A/C compressor, Compressor Anti-Slugging Strategy (CASS) is utilized.

CASS is initiated only under specific conditions:

When the ignition is OFF for more than 8 hours
When the ambient temperature is above -4°C (25°F)
When battery voltage is above 8.5 volts during engine cranking
When these conditions are present, the PCM will activate the A/C control relay prior to cranking of the engine. The A/C control relay engages the A/C compressor for approximately 4-15 A/C compressor revolutions or a maximum of 2 seconds (depending upon vehicle application), allowing the liquid refrigerant to be pushed from the A/C compressor. CASS is initiated by the PCM regardless of the function selector switch position or the HVAC system settings.We have alot of customers that have the same issues.Hope this helped.

[GeritGoul]

Hey i respect everyones advice and thoughts (ps im not the OP) but i was leavin wataburger today and it did it louder than ever..i sounds more like metal parts slamming together? ? i mean would the things you guys are talkin about make the same kind of noise? ?

[Cindy]

It happened to me also. It lasted off and on for about 4 months and then
it just stopped. I haven't heard it since. So hopefully it will just stop
for you also. If you find out what it is, please let us all know.

[Nuke]

Originally Posted by turbotbirdguy79

I think what your hearing is completly normal.Its called CASS.Liquid refrigerant may accumulate in the A/C compressor under certain conditions. To alleviate damage to the A/C compressor, Compressor Anti-Slugging Strategy (CASS) is utilized....

... CASS is initiated by the PCM regardless of the function selector switch position or the HVAC system settings.We have alot of customers that have the same issues.Hope this helped.

Are there any steps that can be taken BEFORE shuting off the engine that would evacuate the compressor so the CASS won't initiate on the subsequent startup?

[turbotbirdguy79]

Im not really sure how you would go about doing it.I know it can be loud as hell sometimes though,the first time it happend in my car,I was afraid to pop the hood to see what happend.I dont know if theres something in pcm strat that can be modified,Im sure its possible though.

[harraid5711]

mine does it as well and i don't have the plenum cover. it's not too loud, but definately bothersome. i've noticed that i can "feel" it if my foot is pushing on the clutch or brake at the time it happens. happens more when cold....