Trane RTAA Winding temp alarm

[Cowpoke]

That model did have crappy plug terminations at the board. Always having to pop the plastic caps and push in on the wires to reestablish good electrical contact. If you want to bypass the safeties as for a failed winding temp stat just add 75 ohm resistors at the board. I hope you don't let the smoke out. Instead of guessing you really need to get the SBs and determine whether its the board, wiring, or sensors or you actually do have a motor over temp condition. If its an old machine the efficiency of the condenser could be low. On other brands I have had to use a hp switch to energize unloader to keep machine on line.

Oh, I for sure ain't going to start guessing. I am guessing on what to check if you want to say that. But I ain't guessing on what to replace! I always checked to make sure the connectors were pushed on good but didn't think to check the actual wires pushed into the plastic piece. Thanks for the idea.

[Manu1]

Been having problems with a RTAA 100 ton chiller, two circuits. I replaced circuit B compressor about a month ago and it has been running fine until the past week. We have had 100F ambient air also for the past month down here in Texas. Circuit A is fine. On install, I weighed charge in to 100lbs. Unit calls for 98lbs but I added a suction line drier. It is a remanufactured compressor and was shipped with no oil. I follow directions and put about 2 pints in suction cavity of compressor and primed oil filter two hand pumps of oil. I also put in fresh three gallons of Trane 15 oil. I previously cleaned entire system because of burnout. After changing drier cores out multiple times I checked for acid and system was clean so I took suction drier cores out and button her up. I added two extra pounds of freon because of the extra piping. So it has been running fine for a month and that was the history of it. Now it is going off on winding temp. I have checked all condenser fans, cleaned condensers very good, checked for restrictions on LL drier all good. Got a clear sight glass, around 5-6 superheat and 18-19 subcool. I have a normal suction pressure, about 90psi with 65F water leaving. Head pressure is a little high, around 360. I cannot seem to find anything about the compressor winding stats. The cover of the panel on top of compressor shows three t-stats, I have mine hooked up from W to BT. What are the three for? Can I switch them around if maybe one is faulty? I'm open to ideas, thanks!

The easiest way to check your t-stat (klixon) is: whith the chiller running touch the motor area, right below the motor terminal plate, those motor winding t-stats open at 221°F and re-close at 180°F, if they are in fact protecting the motor on high temp you should be able to feel it (hot), with a suction SH of 4-5°F the motor should be cool, if that is the case you have a t-stat out of calibration and you need to find which of the 3 is and by-pass it.

[Cowpoke]

The easiest way to check your t-stat (klixon) is: whith the chiller running touch the motor area, right below the motor terminal plate, those motor winding t-stats open at 221°F and re-close at 180°F, if they are in fact protecting the motor on high temp you should be able to feel it (hot), with a suction SH of 4-5°F the motor should be cool, if that is the case you have a t-stat out of calibration and you need to find which of the 3 is and by-pass it.

Alright guys, I checked the chiller out today. Everything was normal. I have come to the conclusion that it is one of the t-stats that is a nuisance trip. If you have been readin along you know that I have already replaced the MCSP, since it wasn't de-energizing the male unload solenoid. But I believe the damage has already been done to one of the stats being I had reset it over a couple of days until I found the problem. It's probably a weak t-stat now and opens prematurely. After coming home and reading your post Manu1, it has to be the case because I have felt the compressor a couple of times after it has tripped and it never felt hot. I didn't know that they were under the terminal plate, but I have felt the suction end where the windings are at, which was cool with a little sweat...all the way to under the terminal plate, which was cool/warm. By the way, where did you get information about the winding stats? I only found what temp they open at and that's all! Thanks everyone for the help.

[caddy]

Had a similar issue on a comp with nuissance trips. Found issue to be the terminals for the stats were sweating and causing them to rust and therefore did not have a good contact. Resolved by cleaning terminals at comp withs some sand cloth and then connecting wiring and coating with corrosion inhibitor. SP400 I believe, got if from Grainger.

[Bklyntek]

Bklyntek, here, hope all is well. Had a similar problem last
Year. New contract, owner had RTAA070.compB tripping hi
Motor winding temp. Stumped me for awhile, finallyclimbed
On top, found c fans right behind bad. My fault assummed
They were for ambient controlled. Well, changed both and
Never had a problem to this day. At same time, changed
Both oil filters on.compressors. Just thought I'd chime in,
Take care, guys.

[milkyway]

Had a similar issue on a comp with nuissance trips. Found issue to be the terminals for the stats were sweating and causing them to rust and therefore did not have a good contact. Resolved by cleaning terminals at comp withs some sand cloth and then connecting wiring and coating with corrosion inhibitor. SP400 I believe, got if from Grainger.

Me too.,