replacing compressor

[lorano]

Hi Guy's

was replacing a compressor in a Williams whu 4518y condenser today,Tecumseh compressor complete with new electrics.Problem i have is i cant get the compressor runing,i have had it run but the start capacitor starts to 'crackle' so i shut i down.The only differnece i noticed id that ALL the compressor cables went straight to the relay in th eold electrics box but on the new one only the run cable goes to the relay the common and start are hooked up to terminals besdie the relay.I swapped all the cables from the old box to the new box but the only thing that will run is the fan?Does anybody have a wiring diagram for one of these?

[Frikkie]

If it's a CSCR compressor the start capacitor should only be connected for a moment when the compressor starts. Once the compressor is running the start capacitor should be disconnected by the relay. If there's no arcing across the terminals then the crackle noise may be because the start capacitor is not disconnecting. The crackle noise also may means the capacitor may have been damaged already.

Can you add a photo of the wiring?

[lorano]

If it's a CSCR compressor the start capacitor should only be connected for a moment when the compressor starts. Once the compressor is running the start capacitor should be disconnected by the relay. If there's no arcing across the terminals then the crackle noise may be because the start capacitor is not disconnecting. The crackle noise also may means the capacitor may have been damaged already.

Can you add a photo of the wiring?

I'll try and add a photo,bear with me.It was arching across the 2 terminals as if it wasnt being disconnected properly by the relay,being new electrics i tend to look at sumthin i have done or havnt done.I have wired it like for like compaired to the old one,when i hook up the neutral to the start terminal it runs but crackles.

[lorano]

10123
Take no notice of the link cable,that was just to test the condenser fan was working.You can see in the picture that the blue(start)and the common(black)are on terminals.On the old box these cables went straight to the relay just like the Red(run).The red+black at the top left are the pressure switch cables.The brown cable in the middle is the live feed from the isolator,which would give the start cable a constant live?!The cable marke '6' comes from the control panel inside.

[monkey spanners]

Think red is start winding, blue neutral and black is live. If it was a new compressor it should have a wiring diagram in the lecky box.

Found this, may be wrong model though,

http://catalogue.actrol.com.au/wiring/LUH_Wiring_Diagrams.pdf

Looks like live in on 3, lp/hp/stat between 3 and 1, neutral on 2, so everything that needs controlling by the lp or stat etc goes on 1 and 2.

If you put your amp meter on one of the wires from the start cap it will have 0 amps on it when its disconnected, but should have amps momentarily when the compressor starts. (can help see if relay is stuck etc)

[lorano]

Thanks for that mate;-).
If you look at the relay at the top right,the red cable is the start terminal on the comp but its sharing the same terminal as the run capacitor.The start capacitor is the terminal underneath.

[monkey spanners]

1 switch live from pressure switch, brown fan, black to comp, black to relay.
2 neutral from isolator, blue fan, blue comp, blue relay
3 live in from isolator, live to pressure switch
If the wires are not long enough on the fan you can make jumpers to some of the spare terminals below.

This from memory so could be wrong.

Pause vid around 1:14

https://www.youtube.com/watch?v=U0GjSzIPtgM

[1mikeefc1]

Sounds like you've got power to start and run at the same time, have you wired it like for like? If so I think that's took the old comp out.

[Frikkie]

It was arching across the 2 terminals as if it wasnt being disconnected properly by the relay,

If the capacitor is arcing across the terminals I would replace it with a new one. Even if there is a wiring fault it shouldn't arc across the terminals, it is most probably already damaged.

[lorano]

If the capacitor is arcing across the terminals I would replace it with a new one. Even if there is a wiring fault it shouldn't arc across the terminals, it is most probably already damaged.

Went back and ripped out all the wiring from inside the electrical box and started from scratch.Powered it back up and it was fine.Not sure who was last at it but it wasnt right.I wired it like for like after installing the new compressor and as i said the start capacitor was getting very hot so i had to switch it off to stop it blowing.Luckly it wasnt damaged and the system is now running as it should be.Still confused as to what was going on with it?!

[Frikkie]

I'm glad you got it running, I guess you'll never know but the wrong wiring may have been the cause of the other compressor failing.