Why does compressor go "clunk clunk" when it shuts off?

[midhvac]

Just got a used spare refrig. to keep in garage. When it shuts off, the compressor makes a loud double clunk. What causes this?

[Green Mountain]

Death rattle.

[spotts]

when the brake hits that wheel they're running on. My shop fridge does it too.

[Shophound]

High head pressure? How clean are the condenser coils?

[baub]

As you know, the motor/compressor is spring-mounted inside the can. If one of the springs is weak or broken, the compressor will shift when it shuts off, hitting the wall on the tin can.

Similar to when you are installing a replacement tin can, and you give it several violent shakes to activate the magic. Same sound.

[Workhorse]

baub beat me to it. The springs under the compressor are going bad. If they are not gone too far you can sometimes put cardboard under the bad area and it will deaden the noise a little. Most of the time this is not a problem, especially if it is a garage unit.

[midhvac]

Thanks guys. Yeah that's the sound all right.

[Stamas]

Have one that has been doing that for years. Knocks but never misses a beat.

[jrbenny]

My beer fridge in the garage was making that noise...unplugged it...electric bill dropped $15 a month...beer stays in the house now!

[midhvac]

Originally posted by jrbenny
My beer fridge in the garage was making that noise...unplugged it...electric bill dropped $15 a month...beer stays in the house now!

Til you drank it

[craig1]

check to see if the compressor is mounted on springs or rubber motor mounts.

a while back i was helping a neighbor move a very old fridge (1950's prbably) in his basement and the compressor kind of fell out the bottom when we put it on the hand cart. turns out that the spring mounts had completely rusted off the compressor (big @$$ Kelivinator beast of a compressor). We bolted it back in with new springs and he couldn't believe how quiet it was. he said it always used to rattle and klunk, but now it is silent. we also fixed the condensor fan which looked like it hadn't turned in 10 years. i doubt a modern compressor would last that long without a condensor fan. I don't want to even think about the head pressure

[jrbenny]

Originally posted by midhvac

Originally posted by jrbenny
My beer fridge in the garage was making that noise...unplugged it...electric bill dropped $15 a month...beer stays in the house now!

Til you drank it

Ya, beer doesn't last as long when I don't have to walk to the garage for a cold one!

[air1]

Originally posted by workhorse
baub beat me to it. The springs under the compressor are going bad. If they are not gone too far you can sometimes put cardboard under the bad area and it will deaden the noise a little. Most of the time this is not a problem, especially if it is a garage unit.

baub was referring to the springs inside the can. Compressors have springs mounted internaly also.