Older Carrier Flowtronic

[rleo49]

Carrier Chiller M/N-30GB125-650 is displaying code/fault 61 which is a water low flow fault. I replaced the flow switch and it still had the fault. I jumped across terminals 13 and 14 on the microprocessor board and it still cut out on 61. Is it more likely to be the processor or actual flow?

[ON-CALL]

Did you check presure drop across the barrel with the same gauge and check it the design drop which should be written on inside of the controll panel .To veritfy you have enough fulid across the barrel.

[rleo49]

Did you check presure drop across the barrel with the same gauge and check it the design drop which should be written on inside of the controll panel .To veritfy you have enough fulid across the barrel.

It was raining here today but i will check the pressure drop tommorow.

It's been awhile but I think if the thermistors are out of range it could cause the same problem?

[Dallas Duster]

An open flow switch will give you a code 26

[ncboston]

It was raining here today but i will check the pressure drop tommorow.

It's been awhile but I think if the thermistors are out of range it could cause the same problem?

Ran across a similar situation a couple of years ago. Check entering thermistor- might take awhile -or just replace the thermistor they're cheap enough.

[freonrick]

the entering sensor is at the bottom of the barrell, the leaving is in the leaving side pipe. if the entering reads lower than leaving you will get a low or reverse flow. the sensor ought to be matching or close to it. on low flow the sensor at the bottom of the barrell will get colder due to location than the leaving water sensor. you can leave the chiller off for a little while and check the voltage drop on each sensor and compare it with the chart and see what it is reading.

[thecomp]

The old code 61 could be faulty barrel thermister and or the compressor thermister, crossed thermister sensor connections at the board, a bad microproccessor board "not likely", a chilled water valve closed, or someting simple like a coupling on the chilled water pump has failed.

Carrier wisely advises against jumpering anything; however, we all know it is neccessary from time to time.

[DeltaT]

From page 32 of the Carrier Flotronic Reciprocating Liquid Chillers manual dated 8-89. In part:
CODE 61, NO COOLER FLOW -----blaa, bla, bla then half way down it says "When there is no cooler water flow and the compressors are operating, the leaving water temperatue themistor will indicate no temperatue change. But the temperature of the entering water will drop rapidly and the entering water thermistor will detect this. When the entering water temperature drops to 5 F below the leaving water temperature, all the compressors will stop and code no. 61 will be displayed. bla..bla

Then: the error will be caused either by no cooler flow or if the wate is flowing in the wrong dirction through the cooler or if the thermistors are insstalled backwards."

I sure hope you have taken over one of my accounts that I have kept going now for close to 10 years on one of these system!

This customer had the same problem. After chasing down every friggin wire through every friggin panel, checking this and that he remembered that he had changed the supply pump...and he put it in backwards!

The Carrier Catalog number for this manual is 533-044.

[Randy S.]

If you have the flow, then it's probably low load.
As I recall, the water side sensors rarely were a problem.

I remember one that would do it on low load even with a decoupled primary.

[Dallas Duster]

The old code 61 could be faulty barrel thermister and or the compressor thermister, crossed thermister sensor connections at the board, a bad microproccessor board "not likely", a chilled water valve closed, or someting simple like a coupling on the chilled water pump has failed.

Carrier wisely advises against jumpering anything; however, we all know it is neccessary from time to time.

What would you jump out kinda hard to do on these chillers? Jumping out the flow switch you would get the same code.

[ACCMan]

If your thermistors checkout O.K. then you may have a flow issue. If you have an "open loop" system where sediment and trash can enter the barrel you may have enough build-up in the bottom of the barrel to restrict the waterflow in the area of the thermistor.
I have seen this probem several times, but only on open loop process systems.
Most of the time the thermistors just drift out of control range and need to be replaced. The early model 30GB had the thermistors inserted directly into the water or refrigerant circuit!
The newer models used a well to insert the sensors into.
Voltage test is OK.... inserting the thermistor into a cup of water with a thermometer and using an Ohm meter with the resistance scale has always proved to be extremely accurate.

[rleo49]

The entering water t-2 was 10 degrees off according to the voltage chart. Replaced it late this afternoon and did not display 61 anymore but I'm still concerned because according to the voltage readings I have now the entering is still 5 degrees low and leaving is 5 high. What is the tolerance on these thermistors?

[ACCMan]

I know it is more trouble to check the thermistors with the temperature/resistance method... but I have always gotten poor results using the voltage method even with a Fluke meter.
Keep in mind, using either method, the type of connection used for terminating the wire on the circuit board. Invest in the proper tool for inserting the wire into the "connector". I think the board connectors were designed by either Hoover or Eureka.
The early Carrier books said the thermistors checked good or bad....nothing in-between. Most will go out a few degrees causing trips on flow, or oil foaming due to low superheat. A quick test before a lead compressor is replaced due to low oil pressure is to "temporarily" relocate the thermistor over the oil pump to the "plug" side of the suction service valve. This will add superheat to circuit due to the thermistor not seeing the heat from the motor barrel.
Again, be cautious of the unit not having wells for the sensor. They can be purchased from your Carrier dealer and you will make life easier for yourself and others by installing the wells to house the sensors. Later models of the 30GB already have them.