Hello all,

2001 5.4 with no codes showing up. Fine with AC off. Turn AC on and will drop from about 600 to 400, then jump to 800-900 then back to 600. This repeats about once every two seconds as long as AC on. AC off, idle sits at about 600.

While it is doing this, the AC does not cool well. I only notice it when stopped in drive with foot on brake. Engine runs fine as long as moving.

Thanks in advance for any advice

 

Come on, someone must have some advice (please )

NOTE: got someone to sit and hold brake while I watched under hood. A/C compressor is cycling on and off in time with the idle bounce. Low on gas? Bad low pressure switch?

 

How about a lazy IAC not keeping the idle speed constant with the extra load of the A/C. Think about cleaning or replacing.

 

I did a little search on the IAC. Some seem to say clean, others replace. How do you clean it? I think if it's bad, why not try a cleaning before spending bucks on it.

 

Take it off and hose it down with TB cleaner or Brake Klean. (DO NOT USE CARB CLEANER ON ANY PART OF THESE ENGINES)

I cleaned mine two months ago and so far so good. When it acts up again I will replace it.

Next time your idle is acting up tap the IAC with a screwdriver handle and see if that clears it up if so you know what the problem is.

 

[drum roll] THE IAC! After reading hundreds of posts here about it I decided to go with a new one rather than a clean-up (only $40). Problem fixed. I was so sure the problem was the AC since that was the only time it showed up. Talking to a shop owner I found out the PCM can shut off the AC if it thinks the idle is too low, then turn it on when it comes back up. That was the bounce I was seeing.

I am happy now, but would like to ask Ford why they put the IAC in a place only a 6' man could reach, but made the working space so small that a 4' child's hands are needed to R&R the valve.