EXV problems on Carrier 30GT Chiller

Hey ac eagle

The board has not been replaced. Though it may turn out that it needs to. The literature and several guys on this site have mentioned an exv driver board. I am fairly certain that I do not have one, but I will double check tomorrow. The exv cable is plugged directly into the J7 plug of the microprocessor board.

Sensors:

I should have mentioned much earlier when you brought it up that many of the sensors have been replaced. I know both cooler saturation sensors have been replaced along with the LWT. I also think that the return gas for Circuit B was replaced, but not certain. I am confident that they are reading correctly, but I will not completely rule it out because so many people, including you have seen odd things with the sensors.

Location:

I am in Raleigh, North Carolina. How is your summer going in MA, it has been a hot busy one here.

Very busy summer up here in Mass,we just got caught up from summer,we are starting to do and get caught with mid summer and regular schedule inspections. So you working on and older flowtronics Carrier chiller,but same sitution. The chiller I work on has an exv board(micropressor board) with both exv vales. You mentioned your going back on Tuesday??

Hey ac eagle

I am going back Tuesday. I am hoping the converter will be here soon, but I will have to start without it. I will check and double check the sensors and make sure they are wired correctly. Also, I am almost certain that I do not have an exv drive board. Apparently, some of the 30GT units don't have them.

I also want to check that I have continuity between all terminals A-E. Then I will go through the troubleshooting section of the manual.

I had thought about doing the suggestion you offered on Friday (switching plugs on A and B circuits), but I would have to switch the thermistors as well. Not impossible, but it was getting late.

The board can move the EXV. I can hear it. Also heard it open after I restarted the machine after pulling a vaccum from the exv to the LL shutoff I(when I changed the cores)

Do you know anything about these EXV's. I thought that I had a 760 step motor, (think I got that from one of our techs), but the literature says it is a 1500 step motor.

OLD: The machine is a 1996. I suppose the technology has changed plenty since then. But it seems like 1996 wasnt that long ago. Time flies.

hvac-alan,
We started using the 1500 step EXV motor in the machines made from week 20 of year 1995 and forward. That means your machine, with serial 4496 (week 44 of year 1996) will have the 1500 step EXV.

Your contol board part numbers should be as follows:
Microprocessor - # 32GB501074
Relay Board - # 32GB500004
Display Board - # 32GB500044
Driver Board - NONE
EXV - # 30GT660003
EPROM - # HT207101-1-24
RCD Repair Kit # 30GT660009
The Eprom set point is for 29* F. Super heat.

Good luck!

Thanks John:

That clears up the confusion I had with the number of steps this motor has. I have read in the historical part of this site that these type problems have occured when the incorrect EXV was installed.

I will keep everyone posted.

Alan

Hello all,

Thanks for all your input. I went back today and went through the Carrier EXV troublshooting suggestions. Before that, I verified that the EXV was the correct one. It was. Checked senors again. All looked good

During the troubleshooting steps, it appeared that the EXV did the opposite that it should have. When it was supposed to be closed, it was open.

After completing that I checked for continuity in my plug. As I stated before, the last tech told me that he found that the new cable was different than the old one, requiring that the brown wire be switched with the white. This was incorrect. I reversed the wires, reset the machine and the unit ran and maintained 29 degrees of Superheat. As I checked the sensors, I saw that the EXV was reacting to changes in the sensors in the correct way. This solution, of coarse, was not as exotic as I was making it out to be, but has been instructive in checking all the simple things and things that have been changed recently before moving to the more exotic diagnosis.

The bright spot in all this is that I learned alot about this machine and I was able to get some good software---That I have yet to use---still waiting on the Converter.

Quote:

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Originally posted by klrogers

Quote:

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Originally posted by hvac-alan
I contacted Carrier on Friday. They gave me a software program (DOS) that could give me all the thermistor readings in real time and the position of the EXV. I need to get a Telebyte Model 65 Converter in order to hook the unit's board to the my laptop. Is this what you are referring to??? And have you done this before. Apparently I hook up to the no. 3 and 6 pins of the J8 plug on the board.

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"Flashing" the board means that they rewrite the code onto the EPROM or whatever memory they use to store the code. The DOS program they gave you just allows you to read the sensors and EXV position directly.
Are you willing to share this DOS program with others on this site? If so my email is in the bottom left corner of my website.

Kevin

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alan, I have recently worked on 30gt-045 and had similar probs, high superheat fault, swapped the leads on the EXV from the other circuit, all worked ok. Found that the plastic connector plugs become loose and if EXV/sensor leads are to be replaced, replace these connector plugs also, using the correct tool. The EXV is a 760 step (P/No: 32GB402554), replaces the old style EXV. Hope this helps you out. It would be greatly appreciated if you could email the DOS program to me as well (look in profile). Thanks.

Chill Bill

Would be happy to send the little program, but can't find your email address in your profile, please advise

mine is hvac-alan at nc.rr dot com

Alan

EDIT: No email addies in post. Please put it in your profile biography. Thanks!

[Edited by Mod01 on 12-16-2005 at 07:13 PM]

No didnt have to change wires,but have heard sometimes you have too change wires. I believe it was brown and red but dont hold me to that change

It has been a while, but Chill Bill revived this thread and I noticed that I did not give comment on the converter and using the little Dos program to watch all the temperature inputs.

I have used it now and let me tell you it is really niffty. The data changes quickly and you can even see the position of the EXV. The machine really reacts to the changes in superheat. Thanks to all that helped me set up with the converter. It it is certainly worth it when you are getting stumped and want see what the bocard is seeing. I would not condemn another EXV without hooking this one up.

Alan

i had same problem years ago and found that the exv had taken too many steps and cross threaded had to replace exv and sensors.the original problem lied within the sensors.

Is it too late to get a copy of Flotronic Manager?
i have a 30GT110 with too low superheat.

lincheng@netease.com

LIN,

I just spent helf a day and night with this problem on a 30GT-190. Snesors and all boards and exv checked out ok.

BUT sometimes the sensors went way out of line. changed both refrigerqant sensors in cooler and in compressor. ALL fine now.