My A/C Diagnosis: Please Help
Thread Starter
Pro
Joined: Apr 2008
Posts: 564
Likes: 0
From: Houston Texas
St. Jude Donor '08
My A/C Diagnosis: Please Help
Hey guys. Its been a while since I have been on the Tech/Perform side of the c5 forums... haha.
Im having an issue with my AC. Here is whats up.
SOMETIMES my ac clutch will engage... When it does work, the air blows nice and cold. I had my pressure checked:
Low: 40
High: 250
Temp: 85 *f
If the clutch engages on start up, it does not cycle on and off while driving, and is constantly on. When at a stop, I can hear the Fans cycle on and off, but not the ac clutch. However, I can manually turn it off and on with no problem.
On the contrary, If the ac clutch doesnt engage upon turning the ignition... It wont come on. It has sometimes randomly while driving.
I have noticed a slight squeak from under the hood, which gets noticeably louder upon hitting the throttle. How ever when the car temp heats up, the noise stops.
Im thinking that it might be the sensors? Im hoping that since the clutch does engage sometimes, that its not bad. And just not getting the right signals...
I drive a black on black frc in Houston Texas... its hot as hell guys. Any help would be Great.
Any Suggestions?
Im having an issue with my AC. Here is whats up.
SOMETIMES my ac clutch will engage... When it does work, the air blows nice and cold. I had my pressure checked:
Low: 40
High: 250
Temp: 85 *f
If the clutch engages on start up, it does not cycle on and off while driving, and is constantly on. When at a stop, I can hear the Fans cycle on and off, but not the ac clutch. However, I can manually turn it off and on with no problem.
On the contrary, If the ac clutch doesnt engage upon turning the ignition... It wont come on. It has sometimes randomly while driving.
I have noticed a slight squeak from under the hood, which gets noticeably louder upon hitting the throttle. How ever when the car temp heats up, the noise stops.
Im thinking that it might be the sensors? Im hoping that since the clutch does engage sometimes, that its not bad. And just not getting the right signals...
I drive a black on black frc in Houston Texas... its hot as hell guys. Any help would be Great.
Any Suggestions?
Last edited by DeadFred; May 26, 2010 at 10:00 PM.
Melting Slicks
Joined: Jun 2001
Posts: 2,340
Likes: 2
From: Moro IL
I don't have a schematic in front of me to check, but I'd imagine it runs an A/C clutch relay, like most. Try swapping this relay with another of the same part number stamped on it. Try to find something like the wipers or the horn, etc. Something not critical to driving or safety. If this solves your problem, or creates a problem with whatever you switched with, then get a new relay. If it doesn't then it was at least a cheap elimination of one component in the system.
One other thing you might check if it does this first thing in the morning when you start it, try giving the pressure sensor a little flick or shake and see if it then pops on. I just recently replaced the compressor on mine, and after vacuuming the system and recharging, it didn't kick on. I hooked up my scan tool and checked it over and found the pressure sensor was still stuck in a vacuum, gave it a flick and it started reading right. Just two simple tests, I thought I'd throw out there.
Pat Kunz
One other thing you might check if it does this first thing in the morning when you start it, try giving the pressure sensor a little flick or shake and see if it then pops on. I just recently replaced the compressor on mine, and after vacuuming the system and recharging, it didn't kick on. I hooked up my scan tool and checked it over and found the pressure sensor was still stuck in a vacuum, gave it a flick and it started reading right. Just two simple tests, I thought I'd throw out there.
Pat Kunz
Thread Starter
Pro
Joined: Apr 2008
Posts: 564
Likes: 0
From: Houston Texas
St. Jude Donor '08
I don't have a schematic in front of me to check, but I'd imagine it runs an A/C clutch relay, like most. Try swapping this relay with another of the same part number stamped on it. Try to find something like the wipers or the horn, etc. Something not critical to driving or safety. If this solves your problem, or creates a problem with whatever you switched with, then get a new relay. If it doesn't then it was at least a cheap elimination of one component in the system.
One other thing you might check if it does this first thing in the morning when you start it, try giving the pressure sensor a little flick or shake and see if it then pops on. I just recently replaced the compressor on mine, and after vacuuming the system and recharging, it didn't kick on. I hooked up my scan tool and checked it over and found the pressure sensor was still stuck in a vacuum, gave it a flick and it started reading right. Just two simple tests, I thought I'd throw out there.
Pat Kunz
One other thing you might check if it does this first thing in the morning when you start it, try giving the pressure sensor a little flick or shake and see if it then pops on. I just recently replaced the compressor on mine, and after vacuuming the system and recharging, it didn't kick on. I hooked up my scan tool and checked it over and found the pressure sensor was still stuck in a vacuum, gave it a flick and it started reading right. Just two simple tests, I thought I'd throw out there.
Pat Kunz
Melting Slicks
Joined: Oct 2007
Posts: 2,383
Likes: 13
From: Kinston North Carolina
Worth checking:
------------------------------------------
---------------------------------------------
Place a feeler gage between the clutch plate and the clutch rotor.
Important
Make sure that the air gap is even all around the clutch plate and hub assembly.
Tighten the hex portion of the J 33013-B until the air gap between the clutch plate and clutch rotor is 0.40 mm (0.015 in).
------------------------------------------
---------------------------------------------
Place a feeler gage between the clutch plate and the clutch rotor.
Important
Make sure that the air gap is even all around the clutch plate and hub assembly.
Tighten the hex portion of the J 33013-B until the air gap between the clutch plate and clutch rotor is 0.40 mm (0.015 in).
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Thread Starter
Pro
Joined: Apr 2008
Posts: 564
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From: Houston Texas
St. Jude Donor '08
I'll check it out. thanks.
Its pretty damn hot.
@dougbfresh: Funny. Drop dead Fred happens to be one of my fav movies. So i usually use it on forums and such.
Thanks for your help so far guys
Its pretty damn hot.
@dougbfresh: Funny. Drop dead Fred happens to be one of my fav movies. So i usually use it on forums and such.
Thanks for your help so far guys
