2000 F150, 116k miles, 5.4 w/AT, etc. Engine runs great and strong, except when a/c is turned on; then blah - very low on power. Stills runs good when a/c is on, but power is waaayyy down. Is this normal? No other a/c related issues; i.e. no screaming belts or compressor; just very low on power. Any ideas?

Thanks!

 

Its your clutch fan kicking on to cool the motor....between that and the pull of the a/c it will use alot of power.

 

Hmm.. I can't tell the difference at all when I turn the AC on in my 03 5.4..

 

Yea my trucks done this off an on. It was really noticeable the other day, it was my first time to use the A/C this summer and i turned it on then went to turn on the next road and i hit and gas and i thought wow, this is pathetic haha