Alarm:High Saturation Suction Temp

**CJ Courtney** · 08-27-2011, 08:29 PM

Guys I have a 20ton Carrier package unit.Has 4 scroll compressors 2-per circuit (R22)and its couple of yrs old.#1 runs fine and #2 after 15mins goes into this alarm.It being a RTU and 100 plus(outside of Houston,Tx),my suction is 80psi w/both compressors running and 325 high side.Feeling the liq line and compareing to the other circuit it is just alittle warm where the other is hot.For a RTU,I think that the pressures is close,but when the unit shuts off my gages indicate under charge(suction does not peg,only 80-90).Guys I know that my descriptions amounts to someone just rambling on but for now this is what I have.
If someone could explain what causes this alarm and why the unit did not trip on high super heat which (I think) is the suction line being to hot for both.I want to try and understand HSST is.The unit is 48/50AJ w/VFD and has the Comfortlink controls.Does this unit show what the SST is on the display?Thanks for any directions from a misfit----CJ
More info to come Monday afternoon

**HvAckid82** · 08-27-2011, 09:05 PM

You need to add more info. If you are saying the one liquid line temp is hot compared to the other that should point you in the right direction. Make sure coils are clean, condenser fan motors opperating and get super heat and subcooling

**hvacrmedic** · 08-27-2011, 10:11 PM

Originally Posted by CJ Courtney

Guys I have a 20ton Carrier package unit.Has 4 scroll compressors 2-per circuit (R22)and its couple of yrs old.#1 runs fine and #2 after 15mins goes into this alarm.It being a RTU and 100 plus(outside of Houston,Tx),my suction is 80psi w/both compressors running and 325 high side.Feeling the liq line and compareing to the other circuit it is just alittle warm where the other is hot.For a RTU,I think that the pressures is close,but when the unit shuts off my gages indicate under charge(suction does not peg,only 80-90).Guys I know that my descriptions amounts to someone just rambling on but for now this is what I have.
If someone could explain what causes this alarm and why the unit did not trip on high super heat which (I think) is the suction line being to hot for both.I want to try and understand HSST is.The unit is 48/50AJ w/VFD and has the Comfortlink controls.Does this unit show what the SST is on the display?Thanks for any directions from a misfit----CJ
More info to come Monday afternoon

Read the manual. The answers to your questions are in there.

**Phase Loss** · 08-27-2011, 10:44 PM

I don't know about your unit, but it sounds like it's monitoring suction pressure via~transducer and doing a conversion to temperature (hence the high SST alarm)

this alarm would lead me to believe that your controller thinks the suction pressure is above it's alarm parameters for a set time.

**HJ Controls** · 08-27-2011, 11:38 PM

unit uses thermistors. you cannot troubleshoot refrigerant problems without information. what is your superheat, what is your subcooling. are thermistors accurate. comfortlink will show you what the tempertures of the thermistors are, if the machine is using exvs it will show you % open. so first off get the manual and read it then check your thermistors and get subcooling and superheat.

**hvacrmedic** · 08-28-2011, 01:26 AM

I suppose he'll need the manual. Should be one of these.

Comfortlink version 2.x:
http://www.docs.hvacpartners.com/idc.../48_50a-2t.pdf

Version 3.x:
http://www.docs.hvacpartners.com/idc.../48_50a-3t.pdf

Version 4.x:
http://www.docs.hvacpartners.com/idc.../48_50a-5t.pdf

Version 5.x (Current):
http://www.docs.hvacpartners.com/idc.../48_50a-9t.pdf

**mizzouhvac** · 08-28-2011, 10:27 AM

I would agree that reading the manual to familiarize yourself with the unit should be your first step. In the alarms and alerts section it will give you possible causes to your issue. I have alot of time on this particular unit so if you can provide more accurate details (sh/sc etc) i'm sure we can help you.

**Dallas Duster** · 08-28-2011, 12:46 PM

Originally Posted by CJ Courtney

Guys I have a 20ton Carrier package unit.Has 4 scroll compressors 2-per circuit (R22)and its couple of yrs old.#1 runs fine and #2 after 15mins goes into this alarm.It being a RTU and 100 plus(outside of Houston,Tx),my suction is 80psi w/both compressors running and 325 high side.Feeling the liq line and compareing to the other circuit it is just alittle warm where the other is hot.For a RTU,I think that the pressures is close,but when the unit shuts off my gages indicate under charge(suction does not peg,only 80-90).Guys I know that my descriptions amounts to someone just rambling on but for now this is what I have.
If someone could explain what causes this alarm and why the unit did not trip on high super heat which (I think) is the suction line being to hot for both.I want to try and understand HSST is.The unit is 48/50AJ w/VFD and has the Comfortlink controls.Does this unit show what the SST is on the display?Thanks for any directions from a misfit----CJ
More info to come Monday afternoon

Well CJ I would be willing to bet you have a version 2 or version 3 software in there . There are actual pressure transducers on the suction of the compressors but thermistors on the condenser giving you that discharge pressure reading. Start your unit up earlier in the morning when it`s cooler I think your alarms are happening at start-up. Yes it show`s the SST in temps.And just confirm your suction pressure transducers for accuracy.

**MUNC** · 08-28-2011, 04:34 PM

Just a thought, this thing have hot gas??

**CJ Courtney** · 08-28-2011, 05:59 PM

Thanks for all the replys and it has the verison 5 controls and does not have hot gas.This is the very first problem with this unit since it was installed about 2yrs ago right before school started.I did not know about the transducers,I will check that out and see what the actural gage psi is and see what the display shows.In the book under alarm code T123 all it says is high load(which the other circuit will run)and TXV problem.Guessing what "Goodlistener" is saying that the transducer is off from actural gage pressure.Thanks for some guidence and I will go through the manual and read alittle.Hope the school dist. appreciates the outside help,I do---Carroll

**gyhooyabat** · 08-28-2011, 08:03 PM

Hey CJ,

if it hasn't been done yet, you can increase your Hi SST alert delay from the factory setting of 10 minutes up to 30 minutes. this will allow the logic to give the unit a little more time to start bringing the RAT down before it begins to think the load is greater than the unit can handle.

**CJ Courtney** · 08-28-2011, 08:22 PM

Where can I take alook at that?Guessing Configuration,just for my own info---CJ

**Dallas Duster** · 08-28-2011, 08:37 PM

Originally Posted by CJ Courtney

Where can I take alook at that?Guessing Configuration,just for my own info---CJ

Configuration---Cool-----H.SST usually this will knockout both circuits sounds like there is something else going on to me. Good luck.

Also checkout the REV.R right before H.SST and make sure it says Yes, might save you some nuisance alarms in the future.

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