McQuay rps045csa
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  1. #1
    Join Date
    Jan 2012
    Location
    Fresno, ca
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    32

    McQuay rps045csa

    Ok guys im looking for some help. I've been a full time tech for about 2mo. For the past year I've been a parts guy/tech. the company i work for does mostly comercial with a few residentials mixed in there. With that said, I've been given a new account and i want to make sure these units are operating properly.
    I'm checking cooling operation on 3 Mcquay rtu's. 2-30 ton and 1-45 ton.
    The 2-30 ton rtu's were runnig in both stages of cooling this afternoon so I was able to check volts, amps and temps. but the 40 ton was not running. It might be satisfied. i would like to start this unit to check cooling opperation. I read the manual, it has the micro tech II in it. I cant find how to start it.
    Q: What is the best way start this unit?
    model# RPS045CSA

    thanks,

  2. #2
    Join Date
    Nov 2004
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    up in the hizzy
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    1,375
    jump the control at one of the TB or if the blower is running you could also manually open the pump down solenoids.

  3. #3
    Join Date
    Jan 2012
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    Fresno, ca
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    Yeah the blowers run continuously. I'm sorry what is the "TB"?

    tkanks,

  4. #4
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    Nov 2004
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    TB means terminal block, there are a whole bunch on these units, I dont remember a lot about them, the older ones were pump down systems, depending on the tonnage 2 or 4 compressor in tandem. on a call for cooling the pump down solenoid open, suction pressure builds up closing the pressure switch mounted near the compressor, I thinks is like 60# to close 30# to open, if you use a magnet to open the solenoids stick a screwdriver or some metalic object in the coil so if there is a call for cooling it wont burn, I used to work on lots of the units a while back, most of them had the microtech disabled.
    what type of compressor? scrolls, recips?

  5. #5
    Join Date
    Jan 2012
    Location
    Fresno, ca
    Posts
    32
    Yes they are pump down systems. This unit has 4 scroll comps.

  6. #6
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    Jan 2012
    Location
    Fresno, ca
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    This unit has a bunch of terminal blocks. I was a little overwhelmed, i didn't want to jump the wrong terminals. Do you know exactly which ones to jump. Or am i making this more complicated then it is. R to G and Y1? : )

  7. #7
    Join Date
    Nov 2004
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    up in the hizzy
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    Quote Originally Posted by jarganda83 View Post
    This unit has a bunch of terminal blocks. I was a little overwhelmed, i didn't want to jump the wrong terminals. Do you know exactly which ones to jump. Or am i making this more complicated then it is. R to G and Y1? : )
    I cant tell you where to jump without the wiring diagram, those units are a pain, very common to find bad connectors and loose wires.

  8. #8
    Join Date
    Jan 2012
    Location
    Fresno, ca
    Posts
    32
    Ok I'll check out the solenoids tomorrow. Thanks again...

  9. #9
    Join Date
    Sep 2006
    Location
    River Forest IL
    Posts
    70

    Micro Tech II

    Here's a manual for your application-you should get used to using the MII program if you're going to be working on them. You can make adjustments in the controller to get the system to cycle up cooling in the Zone Cooling sub menu. I'd write down the values you find before you try making any temporary changes!
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  10. #10
    Join Date
    Feb 2003
    Location
    Wichita Ks
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    1,452
    read the manual first, you also need to know what type of system you have. Is it a VAV or CV? Is the blower on vfd or just a contactor? If on vfd what is the duct static and fan speed? you really need to know all this if your going to check the freon charge and do you have a load. unless you really know what your doing do not jumper anything. that controller is not cheap and it is no longer made. allow the controller to bring on the compressors. you may have to make some changes to it so they will come on. you can go to mcquay.com and down load additional manuals.

  11. #11
    Join Date
    Sep 2006
    Location
    River Forest IL
    Posts
    70

    Oh yes indeed read the manuals. More than once is recommended...

    Jumper wires are fine on a 10 ton Carrier-I wouldn't recommend them on Microtech II or III. The controller/boards are only going to be around until inventory is exhausted. If you have a lot of units with Microtech II, I'd consider getting the Service Tools software and interface- it's not cheap by any stretch, but if/when the day comes that you need to download/reload code to a board, you will be SOL without it.
    Also, the laptop you will be using to do such downloads can't be the latest and greatest. You can't run anything past IE6, and depending on what programs you've got on your system-you can expect compatibility issues. Johnson made the Microtech II, but once they partnered with York, support vanished. And since McQuay went with Microtech III, even they aren't supporting MII; not offering upgrades to contend with compatibility issues with newer versions of various Building Automation Systems-so a BAS that might have worked fine for years with MII might just decide to start driving you crazy if it's updated.
    Not that I think for one minute that it's McQuay's fault alone that new versions of BAS control programming doesn't work perfectly every time with Microtech II (or III for that matter)-I am by no stretch of anyone's imagination a "control guy", but I've had more than anyone's share of hair pulling trying to get everything to play nice. In my book, if the unit runs fine in stand alone mode (no BAS)-but it goes all bat&*%$ when BAS is hooked up-it's a communication issue.
    Whoa-didn't mean to ramble on. You might be able to tell I've worked a bit on Microtech...

  12. #12
    Join Date
    Jan 2012
    Location
    Fresno, ca
    Posts
    32
    Yeah sounds like you know a thing or two... I found a pdf file online that showed me how to change the occ temp set point. So I drop the set point about 10 and after a few short delays...the comps started 1 by 1. Thanks guys!

  13. #13
    Join Date
    Sep 2006
    Location
    River Forest IL
    Posts
    70

    Do yourself a big favor

    And go through all of your menus-check to see what they are set for. Your equipment may or may not have been set up properly from the get go. When you get the hang of the Microtech II, you'll find ways to dial in the controller that other folks might not have figured out-and sometimes you'll find that things have been dialed out for no good reason.
    Microtech II is a kick %$$ control-but you have to know how it works and what it is capable of.

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