Why on a 05 impala the ac clutch stays on

Question edited for clarity.
Question moved from AC Cars, makers of the AC Cobra to model.

Hundreds of them here!

https://www.google.com/search?q=2006+Chevy+impala.+AC+compressor+bypass+pulley

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Unplug the power lead from the AC compressor.If it stays locked up it a mechanical issue with the new Clutch. If it unlocks check the following. Look at the AC Relay. If it has fused or failed in the closed position the ac clutch will remain engaged. As I don't have the vehicle details I can't provide further details

check that the thermostat in the evaporator box is working as it controls the ac clutch action. If it is not functioning correctly (or the relay that it controls is faulty) then it will continually read hot air and not cabin temperature.

The only thing it could be is the conrtol wire of the A/C compressor clutch relay is shorted to one of the wires grounding at the alternator . The PCM - engine computer controls the grounding for the A/C compressor clutch relay. Find the A/C compressor clutch relay in the under hood fuse box , pull the relay out of the fuse box an look on the bottom . You will see four sets of numbers . 30 & 87 plus 85 & 86 . Take an ohm meter an check pin 85 to ground with the ground wire's behide the alternator connected , you will have continuity . Disconnect the ground behind the alternator an you will probably have a open circuit . When the motor was changed wire's were pinched or something . Most likely . Here , check out the wiring diagram http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model an engine size . Under system click on HVAC , then under subsystem click on HVAC controls . Click the search button ,then the blue link . Fourth diagram down is for the A/C compressor clutch relay circuit. Don't know if know how a computer controlled relay circuit work's . Looking at the diagram .The DB/OR - dark blue with orange trace wire would have to be shorted to one of those ground wire's for the compressor clutch to stay engaged .

You replaced the ac compressor, and the clutch stays on, but the compressor does not run ???
Not sure I am following your info here.
If the ac clutch stays engaged the compressor should be running. You should have one hot and one cold ac line and the radiator fan should be running.

Yes. When you turn on the compressor via clutch Suction line pressures at around 3000 rpm should be around 30 PSI. If pressure stays high it is because the compressor is running but it is not doing squat and needs replacement - bad reed valves.

it's either low (in spite of your readings) or your a/c clutch is not working correctly or you have too big an air gap in the clutch.
First, just disconnect the 2 pin connector from the a/c pressure cycling swithc and jumper the 2 pins with a wire to force the clutch to stay engaged. See if it blows cold then, and stays engaged. You can run this way for about 15 minutes before you have to pull the plug.
report reulsts.

please don't forget to rate.

The A/C compressor or clutch is drawing more than 10 amps.

When your R-134a runs too low it will NOT engage the compressor. You need to refill your a/c system before the clutch will engage, I also suggest finding the leak.

That clutch and coil are serviceable without replacing the compressor but I have had little success with this as usually the clutch gets in that shape subsequently from activity going on inside the compressor which means that clutch is failed generally for a reason.replace the compressor -orfice tube-reciever drier and happy motoring......