A/C Compressor Runs in Off Position - 98 SE Wagon | Ford Escort Owners Association (FEOA)
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A/C Compressor Runs in Off Position - 98 SE Wagon

Discussion in 'HVAC' started by Jason Fox, Jul 3, 2018.

  1. Jason Fox

    Jason Fox New Member

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    We got a 98 SE wagon that had an A/C problem which looked like the CCRM, so we replaced it. The car now has a brand new CCRM and the A/C compressor runs. Here's the thing though, the A/C compressor DOES NOT engage in the A/C or MAX A/C positions. But, it does engage in the Dash Vent, OFF, Floor vent and defrost positions. If the compressor is engaged in, say, the dash vent position and I switch it to the A/C position, the compressor runs for a few seconds and shuts off.

    The car belonged to my daughter's father in law who gave it to us for one of our younger daughters since he could no longer drive. My older daughter drove the car a few times in the last few months her father in law still had it and she said this is haw the A/C always acted as far as she knew. She says the A/C had always been messed up. So the CCRM replacement didn't start this problem. The father in law (now deceased) had the car since new so it follows that the A/C worked correctly at one time.

    Any ideas where to look? Maybe the switch in the dashboard? It is vacuum or electrically operated?
  2. zzyzzx

    zzyzzx FEOA Member

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    Not vacuum actuated!!!
  3. rbailin

    rbailin FEOA Member

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    The HVAC selector switch is both a vacuum switch for the various vent controls, and an electrical switch for the blower motor and A/C compressor.

    If you remove the radio/HVAC panel using an inexpensive set of U-shaped wire tools (after disconnecting the temp control cable to the right of the gas pedal), you'll see a an electrical connector for HVAC. The white wire on pin 4 provides A/C power from the A/C fuse. The orange wire (or orange w/green stripe on the switch side) on pin 3 switches current to the A/C system.

    If you unplug the connector, test the switch side for continuity between pins 3 and 4 with a DVM in each of the 8 positions. Continuity = On, Open = Off.

    You probably have a bad switch. Get a replacement OEM radio/HVAC from the junkyard (97-02) and swap it in. (Easier than trying to replace just the switch.)

    If the switch tests out ok, then there's a wiring harness problem.
  4. Jason Fox

    Jason Fox New Member

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    Thank you! I will look at that today.
  5. Jason Fox

    Jason Fox New Member

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    OK, so I took the radio out and tested the switch with my DVM. As far as I can tell, the switch works fine. Continuity in the A/C positions and the other modes where I have read the compressor is activated. (Right now it is 96 F outside)

    So, with the radio module still out, reconnected the HVAC switch to see what happens. Still functions wrong but, I can confirm that the compressor operation is exactly opposite of the switch continuity, ie: when the switch has continuity the compressor is off. Without continuity the compressor is on.

    I don't see any damage to the wiring harness. Doesn't look like it has been opened up since the factory.

    Now what?
  6. Jason Fox

    Jason Fox New Member

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    Figured it out. Wrong CCRM. US spec CCRM for a car made in Mexico. Since I could not return the CCRM, I fixed the "logic" with an interposing relay.

    Apparently the CCRM had been replaced a number of years ago with the wrong one and they just lived with it. So, when I ordered the same part, I got the wrong one as well.
    rbailin likes this.

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