Mechanics

AIR CONDITIONING AND IAC

2003 Jeep Grand Cherokee • 4.0L 6 cylinder 2WD Automatic • 219,000 miles

So here it is.

I blew the head gasket and repaired the head gasket which went great. Also replaced the intake manifold. All of this went like a dream. Once I put the car back together it wont hold idle when cold and the ac clutch wont engage. The ac light comes on in the cabin but no idle up or clutch engage. I have done the following.

-tried to replace iac.(With new iac rpms at 3k)
-replaced ac clutch
-checked fuses for the ac clutch
-pulled vacuum on the ac and it holds at -40psi and then added 40 lbs to low side
- cleaned throttle body

oh yea and throws a o2 heater code like clock work.

Please help!
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Vengraham
March 4, 2014.




Check for a vacuum leak at intake first use choke cleaner. What is the code it is throwing? I am assuming that this is a manual a/c and not automatic and you have checked all the items in pic and the GROUND at the rear of cylinder head which you removed. For the O2 check this tip all around as you had the head off.
Harness normally rubs through on top of left rear head bolt on 4.0, it has a threaded stud on top of it.


Hmac300
Mar 4, 2014.
I went and rechecked the fuses and relay and they are all ok.

The idle fluctuates between 450 and 600 and there was no idle up with cleaner. (It used to race real bad before I fixed the vacuum leaks) I don't think the iac is moving in and out.

It is a manual a/c.

I could not find a ground to the rear post but I did inspect the harness and no signs of wear.

Thank you so much for your time.


Tiny
Vengraham
Mar 4, 2014.
Try cleaning the throttle plate on both sides and iac hole with choke cleaner they get gummy and may be the problem with the idle. The ground wire at rear of h ead is for O2 sensor so if not connected it's going to give a problem.


Hmac300
Mar 5, 2014.
Throttle body plate is shiny, cleaned when I did the intake manifold.

I have no change when iac is plugged in or not.

Also the ac clutch issue has me stumped.
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Tiny
Vengraham
Mar 5, 2014.
You remember when I said to check the ground at rear of cylinder head? Look back there because that is where the O2 sensor AND a/c clutch both ground. Connect a test light to the POSITIVE side of battery and probe black wire going to a/c clutch it should light up if it has a ground. Then disconnect it and check the item in pic to see if it is getting power then finally have your truck scanned if the air is still not working see if a code will come up. A Apro will need to scan it as autoparts type won't pick these up. I am assuming on the a/c you didn't blow the charge and it is full. Also what was the exact code for the O2 sensor.


Hmac300
Mar 5, 2014.
Update.

I found a short under the fuse box by the battery. This fixed the ac clutch issue. I still have idle problem but I have to let the car cool off so I can see if it is still an issue. I have to wait for the codes to cycle.

I did this if it helps.

I hooked tested the iac and it has power to 2 of the four leads, I connect a new iac to the harness and created a false vacuum leak without installing the iac and the was no reaction from the plunger like thing.


Tiny
Vengraham
Mar 5, 2014.
You iac may be bad but get the codes first. Also look at this picture and very very carefully look at your harness where this pic is. This can effect a lot of stuff. I know you said it was ok but the thing tha tis throwing me is that it ran ok prior to disturbing the harness and head then it isnow screwed up.


Hmac300
Mar 5, 2014.

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