firewalker909

07 F150 Screw, 5.4 auto.

I have had this happen twice now while driving on the freeway. The AC ducts will start blowing hot air, then I hear a grinding noise from the AC compressor. I shut off the AC and the noise stops. Each time I replace the fuse and it works great.

Got underneath and check the wiring and connections. Everything looks good. Clutch cycles fine and I had the dealer check the pressures and everything looks good.

Other than just carrying around a bunch of spare fuses, has anyone else had this problem and did you find a solution?

thanx.

redfishtd

The compressor is driven by a belt .The pulley freewheels until the control signal from pcm energizes your ac clutch relay , it then energizes coil and sucks plates together on pulley .
This heavy coil on the front of the compressor brings the plates together to make compressor turn . There is a spacing between these plates that is adjustable if its too much it can fail to pull in and blow fuse trying once it pulls in the current level drops down .
The cycling is the clutch coming on and off .
I have heard of guys adjusting this gap , I haven't done it . Of course your coil or plug/wires may also be in trouble .
But fuse 14 on my 05 f150 is the high pressure /low pressure signal to the pcm , not the clutch circuit . Either your wires are shorting or one of the switches is going to ground blowing the fuse . Check your year diagram its probably the same . You need to follow these wires ,look for a melted wire or chewed up one . Use an ohm meter on switches to ground after unplugged .

firewalker909

Thanks for posting the video. That may be the problem. If the clutch is not engaging fully that could create the grinding noise and possibly pull extra amperage on the circuit causing the fuse to blow.

redfishtd

The point here is fuse 14 is not the clutch on my 05 . It is the pressure signal to the PCM that controls ac clutch .
No sense working on clutch if the pressure sensors are the bad guys . There should not be any source to grd on these switches. You may have to jump both switches plugs and run ac then run ohm test to ground with pressures hitting the switches .
I would doubt that the pcm is the short but it could be as a last resort . More than likely it is one of the wires in this switch circuit touching a grd during heating or vibration . Follow each one and tape up any area touching anything .
Well somehow I thought you were blowing fuse 14,my bad after re reading your post you don't say the number circuit of the fuse that is blowing . I believe clutch power is 11 and clutch relay is 32 . If you are blowing 11 there is another possibility the diode on that circuit absorbs the kick when the clutch releases . It is very necessary to protect you electrical circuits but if it breaks down the wrong way when energized it could blow the fuse . Do not run ac without it as severe spikes can damage your electric circuits .
Let us know which fuse you are blowing .

firewalker909

Thanks again for the reply redfishtd. It is fuse #11 (AC clutch).

redfishtd

Don't know how much a new one will be . The diode is only supposed to conduct when reverse power polarity is applied, with the kick when shutting off clutch . If it breaks down occasionally when clutch power is applied it would then blow the fuse .
Diodes do fail when the junction inside starts to break down .
Heavy coils like this can put out an awesome kick ,that's how you get high volts for your spark plugs .
Of course the ac clutch coil can start to go bad . it is usually epoxy poured coil and a turn to turn short is always possible on any coil .

CJBill

Hey Guys. I know this is an old post but a google search pulled it up when I searched 2006 f150 ac clutch. I am having a similar problem. I have the number 14 fuse blowing. I saw that it had many items on that fuse. One is the ac pressure switch. I did not notice that it said pressure switch and assumed it was for the compressor. I unplugged the compressor clutch and it hasn't blow for months. I decided to get a new clutch and started to replace the clutch and found this forum post. Fuse #11 is for the clutch. Why would it stop blowing fuse #14 when I unplugged the compressor?