AC turns on than clicks off

[Viva Las Vegas JDR]

hey guys I have been using the ac well early this morning I noticed it was hot and the ac would not turn.. so I shut down the front ac and started using the rear ac.. Later I tried using the front ac again but when I first turn it on you can hear the compressor click on and started to hum but after a 1/2 second the ac turns off.. the fan works when put into fan mode.. any ideas what I could test.. oh and the breaker stayed on the hole time..thanks in advance

JDR

[folivier]

Roof airs or basement airs?
If basement turn on then see if compressor hums, and see if that fan runs. Could be a start capacitor for either or the fan could be bad. Remember that the basement units are similar to a house central unit and are split: outside compressor with fan and inside evaporator with fan.

[prairieschooner]

Just for giggles, check the voltage while the Air Conditioners are running.
Low Voltage raises the Amperage and could have tripped something (Volts X Amps = Watts)

[NewellCrazy]

Since one of the two work, and the fact that it hums gives a good indication that the start up capacitor has died.