Some 30GTN tips.

[Maxt]

This site has helped me out so just giving back a little.
I have been working on some 30gtn's that have the usual issues. The T05X alarms that haunt the 30gtn, oil failure issues, etc etc,
For the compressor Feedback alarms, I had read about relay problems, pressure control snubbers etc.
I have had one genuine relay contact failure. I found a honeywell style relay that is just the ticket for the 30gtn, that is sold by carrier as a totaline part. Its got 2 sets of contacts, one is silver pilot duty and the other is power duty .
I have had a machine that gave a persistent T051 feedback error. Judging from all the jumpers, relays, pressure controls and what not lying in the bottom of the machine, I am not the first guy on this chiller and its problem. I tried hardwiring the molex plug on that circuit, running my own wires, hanging the relays instead of hard mounting, different pressure controls with snubber isolators, the whole nine yards. A couple of times, I got a few days out of it with no alarms, but the alarm eventually came back. I eventually resigned myself to ordering Carrier's feedback board kit, but I found out my MBB did not support this option, so I decided to try a few things before investing 4 or 5K more into this machine.
I put a datalogger across the contacts of the compressor safeties. The datalogger did not show the contacts breaking , but a slight oscillation in the voltage across the safeties. the control relay never does really break, but it causes the coil strength of the relay to slightly fluctuate. Its enough to cause the MBB to see mA 5 dc signal as failed.
My fluke was showing the same minor fluctuation across the safeties, being that its like .2v fluctuation, its not the typical contact break voltage you see like 0 then 24 then 0 etc. This is with the orifice snubbers in place.
So the work around for this is to replace the safeties with manual reset safeties. Jump the 24v loop in the cabinet, and put the safeties in the 120 volt out line from the feedback relay that goes out to the contactor for that compressor. I've done it twice now and works like a charm, and you don't have to spend a ton on the carrier kit.

Next problem, oil failures, washed out oil pumps and broken valve plates.
After trying everything from tech support and the service manual, look at the condensing temperature thermistor. Flow across an orifice depends on pressure drop. If you sporadically get the odd pressure spike on the high side, it overfeeds, then the chiller sends the EXV into a tizzy trying to correct for it. The 30GTN needs to have really stable condensing temperature to work. The condensing thermistor has to be super tight on a clean surface(and on the correct U bend). A dab of heat transfer compound helps to. The standing static temperature check does not work very well on these chillers. You have to watch the thermistor performance as the temperatures are actually changing. I have had 2 thermistors pass the standing temp check no problem, but watch your condensing pressure on the CCN compared to guage, it will never be exact as its deduced from PT tables read from the return bend, but if they stray more than 25 psi from actual guage, its a thermistor problem or the charge is out of whack.
A note about the network service tool 5. I bought it and it came with no instructions, but it can be figured out. Its a thousand times better than trying to troubleshoot off the CCN display, or navigator. The baud rate and refresh rate is a little slow, but you can at least see trends developing among groups of sensors.
About condenser coils, never install fan cycling as a cheap workaround of the motormaster option. The condenser coils can't handle it. I had one machine someone did this on, and the condenser kept popping, finally got MM installed, and its been great since. Also these chillers like to run really low headpressure compared to standard r22 machines, if you are popping circiut breakers, try to get the head down or look for a fan motor control problem. You can set the condensing temperature for the rest of the fans in the CCN, I find that 105 gives the most stable operation.
Feel free to add.

[Dallas Duster]

So like a professional you are you took the schematic off a had a new one edited and put it back on there so if someone else ever works on it. I would hate to know that a schematic that says there should be 24 vac really has 120 vac. Ouch!!! Thats what Carrier would do. But there's more than one way to fix a problem so you do deserve credit for it.

[wolfdog]

Do you have a number for the relay? I have a 30GTN that requires a replacement relay a couple of times a year and it is in the pilot duty side of the relay.

[TheSearcherMan]

The biggest problem I have seen with 30GT's is that the companies send out 5 ton RTU guys out to work on them. Then, you end up with a bunch of parts/wires in the bottom of the cabinet. The most common problem is sensor failure. You shoud have a spare one. If you suspect a sensor is not reading right, just run the new one temporary to the board to find out, this is the fastest way. Also, I am curious how much you guys are paying for these sensors these days, seems they have gotten expensive, at almost a sawbuck.

[Maxt]

So like a professional you are you took the schematic off a had a new one edited and put it back on there so if someone else ever works on it. I would hate to know that a schematic that says there should be 24 vac really has 120 vac. Ouch!!! Thats what Carrier would do. But there's more than one way to fix a problem so you do deserve credit for it.
I marked and noted the existing with a sharpie... I would also expect a professional to put a volt meter to the wire before touching it as well.. Any wire for that matter.
The relay number is P283-0343.

Its not so much the people that get sent out, it's Carriers useless tech support which is nothing more than someone on the other end of the phone reading back to you the same manual you have in your hands coupled with the issue that the same manual doesn't cover the full scenario of problems that can be had.
They are a pretty complicated machine, and Carrier at the parts/service level knows very little about them. I've had some good answers from Carrier, but it came from about 4 levels up past tech support from the actual chiller engineering division.
Also, there are a lot of service bulletins on these machines, if you are having issues, take the model serial to the parts counter and they can print them out.

[wolfdog]

Thank you sir.

[TheSearcherMan]

Well, from a service stand point, most all the answers are in the IOM.

[Maxt]

I would argue that, the T051 error section doesn't even come close to whats going on. I've had exv's and thermistors pass the IOM tests with flying colors, but not work correctly in operation. There is no test in IOM for when an MBB has a specific problem. Not to mention it doesn't even talk about condensing pressures when you have a floodback problem.
To me it seems if anything the IOM leads you down a path you don't have to go down most of the time. I got past a lot problems by ignoring what the manual and error code says what the problem is and treating it like a standard refrigeration system.
I find Carriers manuals to be pretty poorly written actually.

[TheSearcherMan]

Well, I find Carrier and Trane manuals to be excellent. They do however demand a certain amount of knowledge, education, experience, and common sense. If they put any more information in their manuals, anybody will be able to diagnose a problem, where will that leave us? Cell phones have created an industry of "telephone techs", and this is unfortunate as it has and is keeping the labor rate down for the top techs who do not need a cell phone to tell them how to wipe their_________.

[klove]

Well, I find Carrier and Trane manuals to be excellent. They do however demand a certain amount of knowledge, education, experience, and common sense. If they put any more information in their manuals, anybody will be able to diagnose a problem, where will that leave us? Cell phones have created an industry of "telephone techs", and this is unfortunate as it has and is keeping the labor rate down for the top techs who do not need a cell phone to tell them how to wipe their_________.


Aren't you the one that's asking for service literature for a YK?

Seems to me that ol' Max has done a pretty good job of researchin' things and handlin' his problems. I for one can assure you that what you get in an IOM and what you can get from engineering level tech support ain't even within shootin' distance of each other in most cases, regardless of the mfr.......

[Tech Rob]

Well, I find Carrier and Trane manuals to be excellent. They do however demand a certain amount of knowledge, education, experience, and common sense. If they put any more information in their manuals, anybody will be able to diagnose a problem, where will that leave us? Cell phones have created an industry of "telephone techs", and this is unfortunate as it has and is keeping the labor rate down for the top techs who do not need a cell phone to tell them how to wipe their_________.

This is a pretty ridiculous statement.

[Dallas Duster]

Aren't you the one that's asking for service literature for a YK?

Seems to me that ol' Max has done a pretty good job of researchin' things and handlin' his problems. I for one can assure you that what you get in an IOM and what you can get from engineering level tech support ain't even within shootin' distance of each other in most cases, regardless of the mfr.......

Now now Klove I can see both sides of it. You don`t go and reinvent the wheel for problems that already have factory fixes. It kinda screws it for the FNG that looks at the chiller. How long is that sharpie schematic going to really last. Granted he did his homework and sounds like he might have more testing equipment than most of us guys in the field and just got bored. The manuals that you get with the chiller are mainly good for the end-user(owner, maintenance guy ,whoever) I know quite abit about Carrier and on this chiller there is not much more than the Controls,Start-up Manual, and Bulletins. But that ain`t gonna fix it if you don`t understand what your looking for. ol`Max said it himself . "it`s just refrigeration right" ? I guess my pet peeve is changing wiring and then having a amatuer artist revision added on top of the original. Like I said the FNG is gonna have a hard time.:couch:

[klove]

Now now Klove I can see both sides of it. You don`t go and reinvent the wheel for problems that already have factory fixes. It kinda screws it for the FNG that looks at the chiller. How long is that sharpie schematic going to really last. Granted he did his homework and sounds like he might have more testing equipment than most of us guys in the field and just got bored. The manuals that you get with the chiller are mainly good for the end-user(owner, maintenance guy ,whoever) I know quite abit about Carrier and on this chiller there is not much more than the Controls,Start-up Manual, and Bulletins. But that ain`t gonna fix it if you don`t understand what your looking for. ol`Max said it himself . "it`s just refrigeration right" ? I guess my pet peeve is changing wiring and then having a amatuer artist revision added on top of the original. Like I said the FNG is gonna have a hard time.:couch:

I don't know Max, and to be honest, my comment was mainly toward the searcher and what he said. It never hurt my paycheck just because other guys couldn't troubleshoot. Actually made it better. I've also spent my fair share of time on the phone with tech support, but that doesn't mean that I'm any less of a mechanic. I'm with Rob on this one.

I'm in complete agreement with what you say, also (as opposed to Max), because this issue is truly two-sided. It just depends on which side you happen to be standing on when the problem needs to be resolved. I've personally been a part of factory recall issues that were "don't fix it 'til it breaks" status. If it doesn't break in warranty, the customer is hung with the problem when it craps out, and the confidential service bulletins are filed away at the factory so noone is the wiser that anyone at the mfr knew that a problem existed. Now the customer has to get it fixed, and sometimes revamping something is in order, but what to revamp? Without those bulletins, you're stuck with doing the best you can, and all the mfrs have them. I went behind several good mechanics that tried hard and just didn't have the right info when I was with the factory. Never called foul on anyone for going above and beyond when they did the best they could with what they could get. That being said, I don't like to be the poor schmuck that has to try and interpret someone else's hand-drawn revisions on wiring diagrams any more than the next guy does.

Contractor mechanics, regardless of how knowledgeable they might be, rarely have access to factory confidential service lit and bulletins, and what I was mainly driving at is that no matter how good you are, there's things that you can't figure out on your own because they truly are design issues. If the factory has a fix for a problem, they need to put it out there. Otherwise, it's left up to the Max's of the world to do the best they can by their customer and I have to applaud them for doing it with very little to work with at times.

[thrashme]

I'm having one of the TO51 intermittent errors. Reset alarm, monitor chiller, loads up suction pressure looks good, once the fans start head pressure is ok, but fans seem to be delayed on start. By delayed, I mean, head reaches 275 - 300 psig before other fans turn on and head drops. Thanks for the tip on double checking SCT sensor.

Tomorrow I will be at job site, changing "B" compressor and will be investigating the TO51 more .

[Maxt]

I don't know Max, and to be honest, my comment was mainly toward the searcher and what he said. It never hurt my paycheck just because other guys couldn't troubleshoot. Actually made it better. I've also spent my fair share of time on the phone with tech support, but that doesn't mean that I'm any less of a mechanic. I'm with Rob on this one.

I'm in complete agreement with what you say, also (as opposed to Max), because this issue is truly two-sided. It just depends on which side you happen to be standing on when the problem needs to be resolved. I've personally been a part of factory recall issues that were "don't fix it 'til it breaks" status. If it doesn't break in warranty, the customer is hung with the problem when it craps out, and the confidential service bulletins are filed away at the factory so noone is the wiser that anyone at the mfr knew that a problem existed. Now the customer has to get it fixed, and sometimes revamping something is in order, but what to revamp? Without those bulletins, you're stuck with doing the best you can, and all the mfrs have them. I went behind several good mechanics that tried hard and just didn't have the right info when I was with the factory. Never called foul on anyone for going above and beyond when they did the best they could with what they could get. That being said, I don't like to be the poor schmuck that has to try and interpret someone else's hand-drawn revisions on wiring diagrams any more than the next guy does.

Contractor mechanics, regardless of how knowledgeable they might be, rarely have access to factory confidential service lit and bulletins, and what I was mainly driving at is that no matter how good you are, there's things that you can't figure out on your own because they truly are design issues. If the factory has a fix for a problem, they need to put it out there. Otherwise, it's left up to the Max's of the world to do the best they can by their customer and I have to applaud them for doing it with very little to work with at times.

Lets not make a mountain out of a molehill with the schematics, all I had to do was draw 2 pressure controls into one line, and mark out the old ones and draw a jumper. Its not like a person has to redraw the whole MBB on the door. In the end it achieves the same as the carrier kit, which is providing the MBB with a reliable 5vdc feedback.
I have recorded every condition and operating parameter on the inner door of that machine. The next person that works on it will have whole lot easier time than I did with it. :).
As for getting the carrier kit, one must remember that not all of us are stateside with instant carrier delivery or support, sometimes when we have to wait weeks for parts, a man has to do what a man has to do.