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99 Civic A/C Help -- No Condenser Fan Or Compressor Clutch Engage
Hello, have read many threads here but never seem to find a COMPLETE thread that goes to the finish.
RonJ the poster seems to offer great advise but the threads folks post just die.
I am at the thermostat wire harness:
I have 12v to ground on the Blue/White wire and when I ground it the condenser fan comes on.
However, nothing else does, there is no voltage on the Black/Yellow Or Blue/Red.
Seems the Black/Yellow should also have power as well according to this schematic:
Thoughts anyone? RonJ?
Thanks
Last edited by Cowpoke; 06-15-2016 at 05:01 AM.
Reason: Forgot to enter year of vehicle 99 Civic, I edited the title
re: 99 Civic A/C Help -- No Condenser Fan Or Compressor Clutch Engage
Of course you did check for blown fuses, especially #56 and #17.
Everything plugged in, measure voltage at the blue/wht wire leaving the thermostat. It should be 12 volts with the A/C off and go to near zero when you press the button with the interior fan on. If that doesn't happen, confirm constant 12 volts on the blk/yel wire and varying voltage on the blu/red wire.
You can also jump the blu/wht wire to ground, this should start the fan and compressor (bypassing the control panel and thermostat). If that works, try jumping the blu/red to ground, which only bypasses the control panel.
re: 99 Civic A/C Help -- No Condenser Fan Or Compressor Clutch Engage
Originally Posted by mk378
Of course you did check for blown fuses, especially #56 and #17.
Everything plugged in, measure voltage at the blue/wht wire leaving the thermostat. It should be 12 volts with the A/C off and go to near zero when you press the button with the interior fan on. If that doesn't happen, confirm constant 12 volts on the blk/yel wire and varying voltage on the blu/red wire.
You can also jump the blu/wht wire to ground, this should start the fan and compressor (bypassing the control panel and thermostat). If that works, try jumping the blu/red to ground, which only bypasses the control panel.
Fuses are good. 12V on the Blu/Wht regardless if I press the A/C button on/off.
Zero Volts on the other two wires (Blk/Yel & Blu/Red) to ground regardless if the A/C button is on or off with the ignition key turned on.
re: 99 Civic A/C Help -- No Condenser Fan Or Compressor Clutch Engage
The blk/yel wire needs to be 12 volts all the time with key on. Turn key on and confirm 12 volts on both sides of fuse 17. If that's OK, you'll need to trace the blk/yel circuit from the fuse to the thermostat.
re: 99 Civic A/C Help -- No Condenser Fan Or Compressor Clutch Engage
Originally Posted by mk378
The blk/yel wire needs to be 12 volts all the time with key on. Turn key on and confirm 12 volts on both sides of fuse 17. If that's OK, you'll need to trace the blk/yel circuit from the fuse to the thermostat.
OK, got it. 12V is present at fuse only when key is on. So now will search out the wire. I have to go back to my night job for three days so won't be until Sunday as I am gone 14 hours a day.
But will report back after the trace.
Thanks MK
re: 99 Civic A/C Help -- No Condenser Fan Or Compressor Clutch Engage
On both my EG and EF I've found the AC switch to be at fault. In those cars, the AC button is the final stop in a series of switches, that once all closed, grounds out the signal coming from the ECM. Once grounded, the ECM will fire up the compressor. The current coming from the ECM flows in the following order:
- ECM voltage source
- AC Pressure Switch
- Thermostat
- Heater Control Panel (through the blower motor control)
- AC Push Switch
- Ground
Your wiring diagram doesn't show the portion of the circuit that's inside the heater control circuit board.....or it's interaction with the blower motor switch. Most likely this area will be the source of your problem.
In my EG, there is a bad solder joint on the board where the switch is. If I tweak the board a little the compressor fires up. Pushing on some of the nearby buttons with a little force is enough to tweak the board inside and fire up the compressor. This is how I realized the problem was a solder joint.
Re: 99 Civic A/C Help -- No Condenser Fan Or Compressor Clutch Engage
Based on what I've read in the thread, the problem seems to be a break in the red marked section of the Blk/Yel wire or a broken corresponding pin in the thermostat connector.
Re: 99 Civic A/C Help -- No Condenser Fan Or Compressor Clutch Engage
Originally Posted by RonJ
Based on what I've read in the thread, the problem seems to be a break in the red marked section of the Blk/Yel wire or a broken corresponding pin in the thermostat connector.
06-14-2016, 06:28 PM
99 Civic A/C Help -- No Condenser Fan Or Compressor Clutch Engage
