ac help
Thread Starter
Cruising
Joined: Jan 2007
Posts: 12
Likes: 0
From: spout spring va.
ac help
i have a 91 vin. 8. the ac clutch wont engage. my manual is telling me to connect test light between b8 of c1 and b+. c1 is my c60 plug. my control head only has one plug and it is c68. what is going on? i have no power to my low pressure switch and relay is fine.
Last edited by craneman; Jun 5, 2007 at 08:21 PM. Reason: miss spell
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
C68 is the auto climate control system.
C60 is the manual system.
Disconnect the negative battery terminal for a couple of seconds then reconnect it. This will clear the Low Freon code if it was set.
Start the car. Turn on the AC and see if the clutch will engage.
C60 is the manual system.
Disconnect the negative battery terminal for a couple of seconds then reconnect it. This will clear the Low Freon code if it was set.
Start the car. Turn on the AC and see if the clutch will engage.
Last edited by Hooked on Vettes; Jun 6, 2007 at 12:19 AM.
Pro
Joined: Jan 2006
Posts: 667
Likes: 1
From: Centennial Colorado
Also try this diagnostic after you do the above.... Takes about 2 minutes...
http://www.idavette.net/tech/c4diag.htm
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
Here's the schematic for the C68 Clutch circuit.
When AC is requested, the AC Programmer sends a signal to the ECM called AC Request.
The ECM will ground the Gray wire at the Clutch Relay. The Relay closes applying 12 volts from the AC fuse to the Light Green wire at the AC High Pressure switch. If the High Pressure switch is closed, the 12 volts goes to the AC Cycling Switch.
The Cycling Switch should be closed (if it's not, probably the switch is bad or not enough refrigerant in the system). The 12 volts then goes to the AC Compressor Clutch. The Clutch engages and the Compressor turns.
The AC Clutch circuit is disabled if the clutch cycles to much over a period of time. A LED on the control head will flash and set a code 09.
To see if any codes are set do the following.
On the Control Head press the up and down arrow buttons at the same time for 5 seconds. The LED will display -00.
Press the Auto button once.
If 00 is displayed there are no codes.
An 09 would indicate the Clutch circuit is disabled.
The schematics for the C60 are different from the C68.
When AC is requested, the AC Programmer sends a signal to the ECM called AC Request.
The ECM will ground the Gray wire at the Clutch Relay. The Relay closes applying 12 volts from the AC fuse to the Light Green wire at the AC High Pressure switch. If the High Pressure switch is closed, the 12 volts goes to the AC Cycling Switch.
The Cycling Switch should be closed (if it's not, probably the switch is bad or not enough refrigerant in the system). The 12 volts then goes to the AC Compressor Clutch. The Clutch engages and the Compressor turns.
The AC Clutch circuit is disabled if the clutch cycles to much over a period of time. A LED on the control head will flash and set a code 09.
To see if any codes are set do the following.
On the Control Head press the up and down arrow buttons at the same time for 5 seconds. The LED will display -00.
Press the Auto button once.
If 00 is displayed there are no codes.
An 09 would indicate the Clutch circuit is disabled.
The schematics for the C60 are different from the C68.
