2003 Ford Ranger Edge Surges/revs with AC turned on?

[shawn25262002]

Hello Everyone,

My name is Shawn and I'm new to the forum. I am very impressed with this forum as it has a wealth of knowledge and member's that realy know there stuff.

I recently purchased a 2003 Ford Ranger Edge with a 3.0 V6 Automatic and have had a strange problem. No check engine lights have come on either.

The problem is when I turn the AC on the engine surges/Revs up and down. It happens in the park position and it also happens while driving and coming to a stop while flicking the AC on. The surge is strong enough to move the car forward even with the foot on the brake.

Sometimes the surge only happens 1 time immediatly after turning on the AC and sometimes the engine will surge up and down every 3-5 seconds continuously after the AC is turned on. The truck runs great with the AC off.

These are the things I am going to look into. O2 sensor/Blocked intake.

Has anyone experienced this before?, does it sound like I'm on the right track with the diagnosing?.

I apologise to make this so long, I did a search and only came up with one topic related to this but not much info was in the post. I thankyou all for your time.

Sincerly,
Shawn

 

[snake]

Never really looked into what controls the A/C idle, I suspect it is part of the PCM (engine computer). Some models used a solenoid to bump the idle up, but I'll bet yours is too new for that.

I'd look into cleaning the IAC motor, since it is what controls the "normal" idle, and may be what is responsible for the A/C "increased" idle as well. Probably needs cleaning anyway- start with the basics.

 

[Southern3.0]

Do you know how many rpms it jumps when it surges?

 

[shawn25262002]

I realy appreciate you two taking the time to reply.

Snake-I will give the IAC motor a good cleaning, I appreciate the advice on that.


Southern3.0- The RPM goes from start to 2000. You can hear the compressor "click" on as it is activated as it revs up but then it goes back down then seconds later clicks again and revs up and does this over and over like it can't make up it's mind. Its like someone is hitting the gas petal over and over and it can't make it's mind up to stay on course.

I also noticed while driving with the AC on I can faintly hear the compressor continuoulsy "click" even at high speed.

 

[lil red]

correct me if im wrong(i could be,its early)
but all cars rev up when the compressor kicks in, it has to to compensate for the extra load

it sounds to me like, whatever revs the engine while it kicks in is just over-compensateing for the load increase
not sure what that is though, sorry, just not good with newer cars just yet

hope i helped, im usually better at ghetto fab, and ols school fixes

 

[shawn25262002]

Thanks Lil red for the reply. I do wish I could pinpoint what is causing the increased load.

I actualy compared my brother's Ranger Edge (same year and model) to mine and his made one audible click with a very slight increase in engine idle when activating the ac then stayed constant with the idle where mine continues to click with constant surging of the Idle. I had heard low AC charge can cause this so I filled it up but did not fix the issue.

 

[LearjetMinako]

The reving up when the A/C compressor engages is normal. On the selector dial, almost all the airflow direction will use the A/C excpet Vent (only), or Floor (only). It should do its cycle every 10-15 seconds and idle up another 500rpms. As the system runs longer, the idle up should be more progressive as the PCM learns.

 

[shawn25262002]

LearjetMinako- Thankyou for taking the time to help. I am aware the the engine is supposed to rev up to compensate for the extra load put on the engine from the AC but on my truck it revs/idles up and on it's way down (idling) it just about shuts off (truck shakes sounds like it will stall) then it shoots back up to 2000 rpm and does this over and over untill you shut the ac off.

 

[snake]

You may also want to check for an engine vacuum leak. Those cause the computer to freak out and not know what to do with the idle sometimes.

 

[LearjetMinako]

You may also want to check for an engine vacuum leak. Those cause the computer to freak out and not know what to do with the idle sometimes.

Yep, that is something else to check.

You may also want to try the "disconnect battery" trick. It may help, if the PCM learned a bad correction. You might also want to try a bottle of fuel injector cleaner, and see if that improves things.

It could also be time for a tune-up. What is the mileage for your Ranger?

 

[shawn25262002]

I want to thank you all for your time I realy do appreciate it.


The truck has 94,000 miles on it funny you mention dissconecting the battery and fuel injector cleaner, I dissconnected the battery last night and added a battle of the injector cleaner.

I drove the truck alot today and definantly noticed an improvement but went backwards in one area. The improvement was the engine did not constantly rev up and down with AC engaged now when AC is engaged it clicks then revs to 2000 RPM one time then backs down an runs steady which I am impressed with.

But now the truck seems to run/idle better with the AC on?, with the AC off the truck seems to want to stall from lack of gasafter pressing the gas from a complete stop then "catches" itself and thrusting forward...doesnt do it all the time but did it about 3 times today.

I apologise to throw the new problem in the mix. Maybe it's just the system clearing itself out with the system reset and injector cleaner. You guys have been great, thankyou for the help.

 

[shawn25262002]

Hey everyone, I noticed that when I first start the truck it idles at 1000 rpm and gradualy over a few minutes it lower's to 500 rpm.

The truck runs fine with the AC on or off as long as the idle rpm stays at 1000 or slightly above 500 rpm, I noticed after the truck has warmed up for a bit the idle will go slightly below 500 rpm if the AC is engaged at that time the truck revs and surges to 2000 rpm back and forth under the load.

So it seems the truck is having issues maintaining the proper rpm and it seems to happen after the truck is warmed up.

This is a very newbieish question but what rpm should the truck be running at Idle? Thankyou for all your time.

 

[shawn25262002]

Cleaned the IAC valve and at first seemed to help the idle alot but then all the sudden it surged to 3000rpm and stuck there in idle, then took it for a drive and started out fine then idle increased again to 2500rpm without even touching the gas...drove 40 miles an hour without stepping on the gas.

 

[smokey]

IAC valve sounds like it is sticking. clean it again and oil it with a light oil see if it helps if not sounds like it needs replaced.

 

[shawn25262002]

Thanks for the reply. Cleaned it again and still same symptoms.Discount auto has a new aic valve for $51.00 which is comparable to the online prices. Rockauto.com had three different Aic's two were around $50.00 but one was $22.00...not sure why it was so cheap, I didnt see the gasket coming with that one though.