Carrier 30GB075 Issue !help!

[_knight_]

Started having an issue with this chiller where the EXV was freezing up on circuit 'A', which is a tandem circuit, one of these 06Es was just replaced. Well, the EXV was freezing up then locking out on code '68', low superheat.(which from what I was told was doing that even before this compressor locked up). Since I knew I didn't have low superheat (pressures were 160/5), I checked all the thermistors, they all ohmed out properly with the corresponding temperatures that they were at, checking some tech docs on it, the only other things that it says could cause this code was a stuck EXV (stuck open) or misplaced thermistors. Verified thermistor location, ohmed them all out again, all checks out good. So, the EXV appears to be the culprit, it gets changed out. Same. Damn. Problem. There were new thermistors on-site, so I pulled both off of the board that served circuit 'A' on the refrigeration side, the one on the compressor, and the one on the chiller barrel, I hooked up the two new sensors but left them sensing outside temp, around 85deg (I did this for now because replacing the sensors is extensive since they don't have immersion wells, and they were ohming out fine). It still would not open the EXV. Now....circuit 'B'. this one only having one 06E, the compressor runs fine, good charge and on a semi warm day can pull the chilled water down by itself, however when we come back after leaving it running (while waiting for parts on circuit A) that circuit (B) is also down, locked out on a code 55. Now, at this point I want to lean towards it being the board, but I just don't know. A new board is on its way in the A.M. but I want to hear from you guys as other possible issues, carrier tech support was zero help, and told me they did not support, or could help with a chiller that old, please help. I want do well for this customer, they are a church and are in desperate need of getting this fixed, Thanks in advance.

[Six]

Last 30 GTN that did that to me was sensors.

Suction saturation below the EEV and suction temp thermistor at the back of the compressor.

Sometimes they even ohm out fine. You can test the EEV output from the board on those with a red led at the plug.



Pull it off the EEV and use the LED for a visual indication. Or if you have a meter with PWM option you can test the out put from the board.

EEVs on those chillers dont go out often and neither do the boards.

Verify minimum flow after also.

[R123]

I hooked up the two new sensors but left them sensing outside temp, around 85deg (I did this for now because replacing the sensors is extensive since they don't have immersion wells, and they were ohming out fine). It still would not open the EXV.

How would the EXV open if the sensors are just hanging......both reading the same ambient temp? The processor would be seeing the same temp on both sensors which means '0' degrees superheat and it would think the evap was flooding and trying to CLOSE the EXV.

[milkyway]

You said it starting freezing, just checking, is the charge right ,

[Dallas Duster]

What does 160/5 mean?

[_knight_]

How would the EXV open if the sensors are just hanging......both reading the same ambient temp? The processor would be seeing the same temp on both sensors which means '0' degrees superheat and it would think the evap was flooding and trying to CLOSE the EXV.

I tried it with a variation, I hooked up a new sensor, left the old connected which senses the saturated refrigerant temp in the chiller barrel, left the new one hanging sensing outside air which typically goes on the compressor, so it is now definitely sensing a high superheat difference, also tried it with both sensors and vice versa, none of those configurations made any change. I definitely agree with what your saying though, I was just trying anything at that point...

[_knight_]

What does 160/5 mean?

Pressures: 160 head....5 suction . It starts at around 200/60, then slowly drops due to the EXV not opening.

[_knight_]

You said it starting freezing, just checking, is the charge right ,

Yes, this is at factory charge at 122 lbs on that circuit of r-22 on that circuit.

[Dallas Duster]

Pressures: 160 head....5 suction . It starts at around 200/60, then slowly drops due to the EXV not opening.

You got a bad sensor somewhere.

[_knight_]

Last 30 GTN that did that to me was sensors.

Suction saturation below the EEV and suction temp thermistor at the back of the compressor.

Sometimes they even ohm out fine. You can test the EEV output from the board on those with a red led at the plug.



Pull it off the EEV and use the LED for a visual indication. Or if you have a meter with PWM option you can test the out put from the board.

EEVs on those chillers dont go out often and neither do the boards.

Verify minimum flow after also.

Do you happen to have a reference chart for the dcv drop that I can check the temps the thermistors are sensing while it is running?

[_knight_]

You got a bad sensor somewhere.

Are the only two sensors that would cause this the one sensing saturated temp on the barrel and the on on the compressor body?

[Dallas Duster]

Are the only two sensors that would cause this the one sensing saturated temp on the barrel and the on on the compressor body?

Yep what about your water flow?

[_knight_]

Yep what about your water flow?

Water flow is good, circuit b runs great until it eventually locks out on code 55, which is a variation of possible issues not pertaining to the refrigeration circuit. I'll start with the sensors, I'm on my way to the customer now, I'll update shortly upon changing sensors. Thanks for the advice.

[R123]

Did you run the EXV test on the micro? Did you check the wiring between micro and EXV? Did you check the output out of the main base board? Some chillers have an 'amplifier' between the main base board and EXV which 'amplifies' the pulse signal. Did you check that? The test procedures are in the book.

[Six]

Do you happen to have a reference chart for the dcv drop that I can check the temps the thermistors are sensing while it is running?

Download the pdf file ( 30GT-2T_1.pdf )

Table 16 and Table 17

Page 43

[_knight_]

Well. You guys were right, it was the sensors. They ohmed out fine, yet they were the problem. The board got delivered to me but I changed out the thermistors first, turned it on....runnin great. Thank you for all the replies, and thank you for the .pdf commtech, it was all much appreciated.

[CCSPIERCE]

The old Flotronics chillers with 750 step EXV were notorious for the EXV sticking due to carbon deposition in the orifice and exv spool. Cleaning them any time you have got the circuit open is a good idea. Be sure you have a new o-ring before you open up the exv. Secondly, they would stick if just a minute trace of moisture is in the refrigerant, so good dehydration and driers is a must.

I have actually verified the voltage drop measurement at the processor and looked at the readings via flotronics monitor and found discrepencies. By this i mean flotronics monitor was showing say 55 degrees which is actually what the processor thinks it is. However the voltage dcv measurement would translate to a different value sometimes as much as ten degrees off. It is best to try and get a free copy of flotronics monitor into an old windows 98 program and use it.

In some cases i have removed the exv,s, disabled the exv and selected txv on the processor. Installed properly sized txv's and solenoids and wired in the liquid solenoids as shown on the schematics. Basically if your schematic shows the lls wiring then you can do it. Otherwise you have to wire off of the first stage compressor contactor utilizing a time delay relay. The machine is not nearly as efficient as the cooler barrell is not quite as flooded. I converted several machines and most of them are still running years later with no compressor losses.

Any time you are checking the superheat calculations via the sensors; try measuring the actual superheat using suction pressure and an accurate temperature probe ( do not shoot it with a laser) strapped into a well insulated section of insulation. If everything is correct you should see around 10 degrees real superheat with something like 22 degrees sensor superheat. That sometimes can tell you a lot about what is actually happening. The 06e oil sight glass should have a blue steady oil level and not be foaming. Some intermittent foaming is to be expected, but it should not be continous.

Finally, if the job is one in which one or two air handlers have three way chill water valves these machines are slow to respond to load changes from supply water bypass . Suction line accumulators can help a lot. Personally i think all of the 30GB and 30GT series machines should have had suction accumulators.

Just about the time that Carrier got the product line to a good reliable machine, they discontinued it. Still, they are one of the best brine chillers around.

[_knight_]

The old Flotronics chillers with 750 step EXV were notorious for the EXV sticking due to carbon deposition in the orifice and exv spool. Cleaning them any time you have got the circuit open is a good idea. Be sure you have a new o-ring before you open up the exv. Secondly, they would stick if just a minute trace of moisture is in the refrigerant, so good dehydration and driers is a must.

I have actually verified the voltage drop measurement at the processor and looked at the readings via flotronics monitor and found discrepencies. By this i mean flotronics monitor was showing say 55 degrees which is actually what the processor thinks it is. However the voltage dcv measurement would translate to a different value sometimes as much as ten degrees off. It is best to try and get a free copy of flotronics monitor into an old windows 98 program and use it.

In some cases i have removed the exv,s, disabled the exv and selected txv on the processor. Installed properly sized txv's and solenoids and wired in the liquid solenoids as shown on the schematics. Basically if your schematic shows the lls wiring then you can do it. Otherwise you have to wire off of the first stage compressor contactor utilizing a time delay relay. The machine is not nearly as efficient as the cooler barrell is not quite as flooded. I converted several machines and most of them are still running years later with no compressor losses.

Any time you are checking the superheat calculations via the sensors; try measuring the actual superheat using suction pressure and an accurate temperature probe ( do not shoot it with a laser) strapped into a well insulated section of insulation. If everything is correct you should see around 10 degrees real superheat with something like 22 degrees sensor superheat. That sometimes can tell you a lot about what is actually happening. The 06e oil sight glass should have a blue steady oil level and not be foaming. Some intermittent foaming is to be expected, but it should not be continous.

Finally, if the job is one in which one or two air handlers have three way chill water valves these machines are slow to respond to load changes from supply water bypass . Suction line accumulators can help a lot. Personally i think all of the 30GB and 30GT series machines should have had suction accumulators.

Just about the time that Carrier got the product line to a good reliable machine, they discontinued it. Still, they are one of the best brine chillers around.

I agree with you on this, before I changed the EXV I was actually considering going to a txv with due to the price of the EXV, I also agree about the accumulator, but now that it is back up and running, I'm a happy man. Thanks for the input, much appreciated.