Results 1 to 9 of 9
  1. #1
    Join Date
    Jun 2006
    Location
    New Jersey
    Posts
    4,291

    McQuay Slide Position Sensor Fault

    I have a McQuay AGS175CH27 that circuit 2 locks out on Slide Position Sensor Failure, about every 2 weeks. I calibrated sensors on both circuits. Every time I go there and reset it, everything looks good. Slide valves are tracking good. All the connections are tight.

    It becoming a nuisance and making me look bad......anything else I should be looking at?

  2. #2
    Join Date
    Sep 2011
    Location
    Heartland
    Posts
    25
    In my experience, you will have to replace the sensor. 95% of the 3200 frame compressors run flawlessly, but when you have a transducer that constantly is going out of range, it will probably need to be replaced.
    Depending on what version of code you have, the tolerance is either 10 or 15% off of zero. I've never been real impressed with the short stroke transducers used on that compressor. Calibrating them according to the instructions is nearly impossible due to the location of the cap over the button. A simple design change to rotate the plug 90 degrees would eliminate the problem. Now the long stroke sensor used on the frame 4 compressor almost never needs to be replaced. I've probably had to replace 10X as many of the short stroke sensors compared to the long stroke.
    Personally, I wish they simply used motor current rather than a linear transducer.
    Are you resetting the offset to zero before you calibrate the sensor?

  3. #3
    Join Date
    Jun 2006
    Location
    New Jersey
    Posts
    4,291
    The offset was 0 when I calibrated the sensors.

    The problem is everytime I go there, the sensors are tracking good.

    Looking at the manual.....if they go 25% out, I get an error(not a fault). I'm getting a sensor fault. Which says, the sensor is open or shorted. I checked all the wiring and it all looks good. The connections look good.

  4. #4
    Join Date
    Sep 2011
    Location
    Heartland
    Posts
    25
    One last thing to check before changing the transducer is the connection at the Carel controller. I've had a couple where the wire was inserted into the connector too far and was actually crimped on the insulation rather than bare wire. The wire ends will intermittently touch still. Pull the wires and look for the insulation to be crimped on the end. Failing that, you will have to replace the transducer head.

  5. #5
    Join Date
    Aug 2010
    Location
    N.E Ohio
    Posts
    15
    Need to change transducer. The new transducer will have a different tip. Give
    parts the serial no# may be warranty part.

  6. #6
    Join Date
    Jun 2006
    Location
    New Jersey
    Posts
    4,291
    I really didn't get a real good look at the sensor. Being tough to get to with the compressor cover and the location. It was tough enough calibrating these things. You can just replace the head?

    Anyone have a part # for the sensor? I'm trying to avoid giving serial #'s to the company I have to get the parts from. This was their contract up to 4 months ago.

  7. #7
    Join Date
    Sep 2011
    Location
    Heartland
    Posts
    25
    330591102
    There are two small metric Allen screws on either side of the head. Loosen them and you can change it without pumping down the compressor. The old style did not have the calibration button, so if yours does, then it is the same. Either way, they both used the same plunger. It is nothing more than an aluminum rod in a steel tube. Ive never had to replace the plunger when it was a calibration problem.
    Be sure to power down the circuit before removing the plug from the transducer. According to the factory, not doing so can damage the transducer. Remember to leave the cap off so you can calibrate without having to pull the plug again. Personally, if you have the sound attenuation covers on the compressors, then i would just leave the caps off.

  8. #8
    Join Date
    Aug 2010
    Location
    N.E Ohio
    Posts
    15
    Change the entire transducer the small bb type tip has been changed. The old type tip makes a groove in the cone. You will be back to change the entire thing when the groove gets deep enough.

  9. #9
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,429
    Just save yourself some heartache and change it out. We chose to change the whole thing. Pumped it down and left about 20 pounds on the compressor and went for it. Recalibrated and all was good.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event