No voltage to 740il ac clutch

Check for battery voltage on the dark blue/yellow wire in the connector at the AC clutch with engine running and AC on. If no voltage, yank the AC relay and check for battery voltage on terminal 86 in the relay socket. If no battery voltage on that terminal, check fuse 21. If yes, check for ground on terminal 85 in the socket. If no ground, then PCM isn't commanding the AC clutch on. Check for voltage on the dark blue/yellow wire at the low pressure switch and good ground on the black wire. The PCM provides power to the low pressure switch which then goes to ground. The PCM is looking for a large voltage drop if pressure is above 34-38 psi. If pressure is below that, the switch will be open, so the PCM won't see a voltage drop and will prevent AC clutch operation. The high pressure switch should be closed at pressures below 270-330 psi

automotive AC clutch is inside of AC pump drive pully. check to see if you are getting voltage to engage clutch

Let's break this down.
1 Does the fuse blow when the heater is on, or just the AC?
Yes- Fan motor problem likely need new blower motor.
No- 2
2 Disconnect the AC compressor clutch wire. Remove the blown AC fuse, connect a multimeter across the sockets for the fuse, measure DC voltage across the two sockets with the AC switch, and Ignition switch ON. Is Battery voltage present?
Yes- The wiring harness has a short between the output of the AC switch and ground, likely a pinched harness.
No- The AC compressor clutch is shorted. Replace either the whole compressor or the clutch.

Neutral lockout switch or ignition switch if the car is an automatic. Switch on the clutch if it is a stick. If auto try starting it in neutral.

A mechanic would check for voltage at the fuse and relay, and also check the system to see if it is full of freon. If the clutch has voltage and ground it may need to be replaced.

Check for voltage at the AC clutch with AC on and engine running. If no voltage there, check voltage at AC clutch cycling switch.

You have a low voltage problem to the ac clutch,check the voltage to the clutch with it running,see if it is bellow 12.5 volts,it should be closer to 13.5 volts but the ac clutch relay may be the problem,or a trinary switch that is weak,and not conducting ,good negative ground.But check the ac clutch relay,this is most likely the problem.

Trace the clutch wires from the compressor clutch to the nearest plug that you can disconnect. With the engine running, and the AC set to max, check to see if the clutch is engaged. If not, unplug the clutch wires and check the voltage going to the clutch. If the voltage is around 12 volts or more, then your clutch is shot and you will have to replace the clutch and compressor (sold as one unit). If the voltage is low or zero, then your AC is not calling for the compressor to run...a pressure or temperature sensor in your AC is out. Hope this helps.

Locate wires coming from compressor clutch and trace to nearest plug that you can unplug. Turn on A/C to max cooling. If clutch not engaged (center of compressor drive pulley not spinning with pulley), unplug compressor clutch wires and use multimeter to check voltage going to compressor clutch. If voltage is around 12 volts or more, then clutch should be engaged when plugged in. Plug clutch wires back in (with motor still running and ac set to max). If clutch still not engaged, then clutch definitely bad because 12V signal should engage it.

in the relay box under the hood a big black box and usually 3 or four relay fuse buy one and check each one seperatly if not your clutch burnt out