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AC Clutch engagement

bubba308 on Wed June 22, 2011 11:21 PM User is offline

Year: 2001
Make: Chevrolet
Model: Suburban
Engine Size: 5.3
Refrigerant Type: R134
Ambient Temp: 80
Pressure Low: 75
Pressure High: 75
Country of Origin: United States

My Suburban has climate control and dual air. The AC compressor was "liquid slugging." I have replaced the compressor, dryer, and O-tube.
I pulled a vacuum that held and have charged with 3 lb. of R134. This is my first AC job. I disconnected the battery while replacing the components. After reconnecting the battery, I can not get the AC compressor to engage. I have read the climate control has to be reset, but can not find out how to do this. what is the procedure fore getting the compressor to engage.


Any help would be greatly appreciated.


vcp90 on Thu June 23, 2011 1:20 AM User is offline

direct from alldata

Without A Scan Tool

Turn OFF the ignition.
Remove the battery positive voltage circuit fuse of the HVAC Control Module. IMPORTANT: The module memory will not clear if the battery positive voltage circuit fuse is installed in less than 60 seconds .
Wait 60 seconds .
Install the fuse.


With A Scan Tool


Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, select Heating and Air Conditioning.
Select Special Functions.
Select Setup New HVAC.
Follow scan tool prompts

bubba308 on Thu June 23, 2011 8:17 AM User is offline

Thanks for the information.

However, that brings more questions. If the scan tool is the only way reset the AC.

Where can you purchase one, how much do they cost? Is it better to take it to a shop? I feel like I am close to getting it back running, but my time frame is running out.


Thanks again for the help.

bubba308 on Thu June 23, 2011 8:18 AM User is offline

Sorry, did not see read correctly about not having a scan tool. However, I would like to have the other information.

bubba308 on Thu June 23, 2011 8:59 AM User is offline

Hopefully one last question. Should resetting the HVAC control get the compressor to kick in?

Sorry, for the multiple post. I am new to posting and AC repair.

Thanks for helping the novice.

Cussboy on Thu June 23, 2011 9:35 AM User is offline

Quote
Originally posted by: bubba308
My Suburban has climate control and dual air. I have replaced the compressor, dryer, and O-tube. I pulled a vacuum that held and have charged with 3 lb. of R134. This is my first AC job.

I need to ask (don't get offended): did you replace the connector onto the compressor?

Did you jump the compressor positive terminal for 2 seconds with a jumper from battery 12 volt positive (use a jumper wire with a 25 amp in-line fuse) to see if the AC clutch would pull in/click/engage ? This can be done with engine off.

With engine off and compressor plug disconnected, did you measure ohms resistance between the two compressor terminals ?

It appears you have enough refrigerant pressure to actuate the low pressure switch. But your system, with dual air, will eventually require more R134a than you have added. 48 oz might be OK for Suburban with front-only air. I know my 1994 R134a Suburban needed like 65 ounces.

bubba308 on Thu June 23, 2011 10:07 AM User is offline

mk378 on Thu June 23, 2011 10:21 AM User is offline

Yes you should measure if the compressor is receiving voltage (after checking that it is plugged in). The new compressor clutch could be bad (how does the gap look?). I think that disconnecting the battery is the same effect as removing the fuse, so it should have started for you right away.

bubba308 on Thu June 23, 2011 10:22 AM User is offline

Cussboy,

Do not worry about offending me. If you are willing to help, you can say anything you want to me.


The compressor I purchased was new with clutch. So the connector on the compressor side is new. The connector on the truck side is still the same.

I have not jumped a wire to the compressor. I was planning on trying that this afternoon. Is there a way to determine which is the positive and negative side of the clutch coil. If I run both hot and ground is the clutch polarity sensitive.

I have not checked the ohms on the compressor. Do you know how many ohms there should be?

The high and low side pressures are reading between 75 and 80 which I believe should let the compressor run.


Thanks again for the help.

bubba308 on Thu June 23, 2011 11:33 AM User is offline

Should the clutch be engaged with the key on and the engine not running if the AC is turned on. Or will I need the engine running to check this.

I design electrical systems of large fork lifts for a living. However, I am completely ignorant of how the ac controls on my vehicle work.

Is there any kind of sequence you have to do after the computer has been reset.

Am I going to need a scan tool like the first response mentioned.


Thanks again for the help.

bohica2xo on Thu June 23, 2011 12:01 PM User is offline

The engine will need to be running. The PCM disables the clutch until the engine is running.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Cussboy on Thu June 23, 2011 2:51 PM User is offline

Quote
Originally posted by: bubba308
I have not jumped a wire to the compressor. I was planning on trying that this afternoon. Is there a way to determine which is the positive and negative side of the clutch coil. If I run both hot and ground is the clutch polarity sensitive.
Take multi-meter, in ohms resistance mode. Unplugged state, measure ohms resitance from first terminal to compressor body. do same for second terminal. The terminal which reads essentially no resistance (straight conductivity) is the negative.


Quote
Originally posted by: bubba308
I have not checked the ohms on the compressor. Do you know how many ohms there should be?
I believe most AC clutch coils are about the three to five ohm range, across the terminals, while disconnected.

bubba308 on Thu June 23, 2011 3:44 PM User is offline

bubba308 on Thu June 23, 2011 3:47 PM User is offline

Thanks for the information. I am planning on trying these things when I get home.

If these suggestions do not get my problem solved, I think I am going to pay for the information off of alldata.com

Thanks again.

bubba308 on Thu June 23, 2011 7:36 PM User is offline

bubba308 on Thu June 23, 2011 7:41 PM User is offline

Sorry still trying to get the hang of posting.

I hate to even admit what I found to be the problem but I figured you all deserved to know.

While tired last night, I overlooked a fuse that was controlling the ac compressor. Cooling well right now. I hope it last.


Thanks to all who responded and thanks to the forum providers for giving us novices a place to talk to people who know what they are doing.

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