A/C comp. question - Ranger-Forums - The Ultimate Ford Ranger Resource


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  #1  
Old 11-30-2005
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A/C comp. question

i understand how the a/c system works but i dont understand why the compressor kicks on when i have the heater on defrost or the setting where its coming out on my feet and the regular vents. my teacher told me why this happens but i must have had a brain fart cause i have no idea anymore.
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Old 11-30-2005
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To dehumidify the air and prevent additional condensation on the window when the outside air is humid, and to make the defogging more effective when in defrost.

It also ensures that the compressor runs periodically in the "off season" which keeps the system lubricated.

I have an A/C compressor cutoff switch in my EATC though, so I can turn it off when I want.
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Old 11-30-2005
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I posted about my idle problem at redlights and i think its my ac compressor going bad....when im at a red light, or in park ...the idle will drop to 500 rpms and go back up to normal....Is it my ac compressor since you can hear it click in, then it drops down...or my alternator not pumping enough power when it kicks on? it drops drastically, and when your at a redlight the truck jumps...its very annoying...but the battery meter doesnt really move when it does it...so i dont know which it is...but it only does it when the compressor kicks in and when the heater is on....

not to thread jack but i have a question with my ac compressor, haha

Rocky
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  #4  
Old 11-30-2005
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do the A/C MOD so your compressor only comes on when YOU want it too
on modern Rangers the A/C runs in all HVAC positions except full face or full foot
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  #5  
Old 11-30-2005
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anyone have a HOW-TO on this A/C MOD???
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  #6  
Old 11-30-2005
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  #7  
Old 11-30-2005
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sweet thanks guys...thats exactly what i needed
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  #8  
Old 11-30-2005
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Got it all done. turned out nicely too.
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Old 12-01-2005
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Rockysford,

Generally when the A/C comes on; the engine is supposed to speedup a couple 100 rpms to compensate for the increased load of the compressor turning. IF the engine speed drops as much as you indicate..... then the solenoid that is supposed to increase the engines speed IS NOT working properly....

OR 4x4
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Old 12-01-2005
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Quote:
Originally Posted by OffRoad 4x4
Rockysford,

Generally when the A/C comes on; the engine is supposed to speedup a couple 100 rpms to compensate for the increased load of the compressor turning. IF the engine speed drops as much as you indicate..... then the solenoid that is supposed to increase the engines speed IS NOT working properly....

OR 4x4
I agree that it probably an issue with the Idle Air Controller (IAC). You may be able to detect very small RPM dips and flares as the A/C compressor clutch cycles but they should not be extreme.
The PCM actually changes the IAC duty cycle about a half second before the A/C load changes to keep the idle RPM as consistant as possible.
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Old 12-01-2005
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Quote:
Originally Posted by blkb3
Got it all done. turned out nicely too.

Wow Stephan, that was quick! You don't mess around. Good job
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  #12  
Old 12-01-2005
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Quote:
Originally Posted by rwenzing
I agree that it probably an issue with the Idle Air Controller (IAC). You may be able to detect very small RPM dips and flares as the A/C compressor clutch cycles but they should not be extreme.
The PCM actually changes the IAC duty cycle about a half second before the A/C load changes to keep the idle RPM as consistant as possible.

So what should i check with mine? I was going to take a video of the rpms dropping, but they drop from exactly 750 rpms to 500 rpms and then back up, just enough to make the truck jump....So im not sure, but it only does it when you hear the ac click in..

Rocky
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Old 12-01-2005
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My 2001 did that and it was very disconcerting. My 2002 scarely bumps at all.
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  #14  
Old 12-01-2005
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Well it just started, im thinking my ac compressor is going out or something, or my alternator since i just put my 2 12's in but the battery meter isnt low...so i dont know what it is...ill probably wait until it gets worse, or annoying as hell and take it to ford...

Rocky
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  #15  
Old 12-01-2005
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Quote:
Originally Posted by RockysFord
So what should i check with mine? I was going to take a video of the rpms dropping, but they drop from exactly 750 rpms to 500 rpms and then back up, just enough to make the truck jump....So im not sure, but it only does it when you hear the ac click in..

Rocky
The IAC opens more when the engine RPM is lower than desired and less when it is higher than desired. It also should jump to a learned position when a load like the A/C compressor or transmission engagement is anticipated.

I would try cleaning the IAC to see if it makes a difference. If this fixes it, great. The problem may come back after awhile but at least you would know the source.

A search should find you many posts on the IAC.
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