ReplyDid you check the secondary voltage at the transformer with load then no load ?
Professional Member
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.?
Global Moderator
Did you check the secondary voltage at the transformer with load then no load ?
Professional Member
What he said. This is basic troubleshooting, start at the source, and trace until you find where your loosing Vac.
Regular Guest
Check ur transformer if it's good then check ur low voltage wiring even wire nut nuts and plugs.
Professional Member*
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.
Professional Member*
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.
Professional Member*
"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
It`s better to be silent and thought the fool; than speak and remove all doubt.
Professional Member*
Or a compressor shorted to ground....Originally Posted by dandyme
AOP Committee/Professional Member*
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.
[Avatar photo from a Florida training accident. Everyone walked away.]
2 Tim 3:16-17
RSES CMS, HVAC Electrical Specialist
Member, IAEI
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