2000 Ford Mustang A/C Stopped working, Please help! My wife

Tiny
OSSIV99
  • MEMBER
  • 2000 FORD MUSTANG
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 95,000 MILES
My wife drives a 200o Ford Mustang 3.8L V6 and the A/C stopped working. We have changed the mass airflow sensor, I've put a new compressor on, checked the freon level and checked all fuses. Nothing has fixed the problem. The compressor is getting 12 volts but it's not kicking on. The CCRM is getting power too.
I don't know what to do next, please help.
Thanks for your input.
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Thursday, April 22nd, 2010 AT 9:19 PM

3 Replies

Tiny
CARADIODOC
  • EXPERT
Hi ossiv99. Welcome to the forum. If you have 12 volts to the compressor, that just leaves ground and the clutch coil. I can't remember for certain, but I believe the coil is always grounded and the 12 volts switches on through a relay. That's the way most cars are wired. If that's the case, check the resistance to ground on the coil's ground wire and measure the continuity of the coil. One of those two has to be open.

To not overlook something stupid, did you measure the 12 volts with a voltmeter or a test light? If you used a voltmeter AND the connector was not plugged into the compressor, the results can be misleading. The voltmeter will not draw a significant amount of current, so pitted relay contacts that can't pass enough current to run the compressor clutch, will still allow the 12 volts to be seen by a voltmeter. A test light draws much higher current and will cause pitted contacts to show up as low or missing voltage to the coil. For older cars that used special wires for fusible links, the same thing can happen when the wire burns open and leaves a carbon track behind. No current will get to the clutch coil, but voltage will be measured by the voltmeter when the connector is unplugged.

Caradiodoc
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Thursday, April 22nd, 2010 AT 9:38 PM
Tiny
OSSIV99
  • MEMBER
I've checked voltage, there is 12volts w/ no amps
coil is good and engages when I jump it straight from battery
There are good wires to all sensors voltage & continuity is good on all sensors
I did a backprobe on the CCRM connector and got voltage on terminal 21 but not 22 or 23
According to some online diagnostics I was reading, that means the CCRM is bad.
Does this sound correct to you?
Thanks for your help.
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Friday, April 23rd, 2010 AT 8:32 AM
Tiny
CARADIODOC
  • EXPERT
Sorry for letting you sit. My Verizon e-mail is going through major changes, (none of them for the better), and sometimes it goes down for an entire day, then I don't get the automated messages directing me to your reply.

How are you jumping the compressor to make it run? Do you just need the posiitve wire, or do you have to connect a ground wire too?

The most accurate way to measure the voltage on the clutch coil is with it plugged in. When it should be turning on, measure the voltage between ground and the 12 volt wire, then between ground and the ground wire in the plug. If you have 12 volts on the ground wire, that ground wire is the circuit that needs to be looked at.

Caradiodoc
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Friday, April 30th, 2010 AT 12:48 PM

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