Air Conditioning Problem

My central A/C started acting up today. The thermostat is set at 75 degrees, yet the room temperature remains constant at 80 degrees. The air circulating fan in the basement is running and putting out a minimal amount of cold air, but the main RUUD heat pump/ airconditioning unit outside is just sitting there, not turning on. I checked the circuit breakers and none has tripped.
I would appreciate some pointers on where to look for possible causes before I call the repairman.
Thanks.
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franzen snipped-for-privacy@yahoo.com wrote:

There is likely another breaker at the unit, and perhaps another one integral to the compressor.
And there's likely a control board and motor relay which can fail or go into protect mode. Some have status indicators.
Rodents sometimes chew through wires.
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Check the high pressure cutout-- it is a little red button close to where the lines come into the outside unit. Larry
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On Wed, 30 May 2007 17:23:42 -0700, franzen snipped-for-privacy@yahoo.com wrote:

Where is the outside unit fused? Find the fuses and check them (make sure the mains is off.) If you don't know how to do/afraid to do it (230 volts) then call the repairman.
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franzen snipped-for-privacy@yahoo.com wrote:

One of the most common problems is the "contactor" which is another name for a solenoid type relay. It's the final switch (inside the compressor unit/box) that "clunks" in to connect the 240v to the compressor. These go bad after 8-10 years and won't close....in principle, much like the solenoid switch on a car starter motor.
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