drawing 9 volts

[jmiles]

I walked up to Carrier rtu today that was suspected of not having power. when I pushed the contacter in the compressor would start. When i tried jumping r-w or r-g or r-y Nothing would activate. I checked voltage and was drawing 9 volts from r to ground. what would cause this voltage reading? bad transformer.?

[VTP99]

Did you check the secondary voltage at the transformer with load then no load ?

[Purcell1]

What he said. This is basic troubleshooting, start at the source, and trace until you find where your loosing Vac.

[BMH_SE]

Check ur transformer if it's good then check ur low voltage wiring even wire nut nuts and plugs.

[Crazecodyk]

Check your supply voltage to your primary side of transformer, make sure correct voltage is being used.
Then i would check on output side of transformer,
If all good there check for loose connections, and possible bad coils.

[54regcab]

Bad splices/connections can be gremlins in a machine. Look for connections that are twisted and taped instead of having wire nuts on them. I've seen a few bad ones.

[dandyme]

"pushing" the contactor in will bite you inn the ass one of these days

if you never see a part start compressor winding, you'll be fine

[ryan1088]

"pushing" the contactor in will bite you inn the ass one of these days

if you never see a part start compressor winding, you'll be fine

Or a compressor shorted to ground....

[timebuilder]

In a carrier RTU, if I have low voltage, the very first place I go is that high temp cut out with the little red button over in the blower section. Then I look to see if there's a smoke detector wired in.

After that, I look at the transformer as explained above.