Carrier 48AKT020 AC 111 HJ

[Entity]

I am having trouble with this roof top going into alarm on low saturated suction temp on both A & B circuits. My temps read normal it appears(using Network service tool V). Hoping someone can explain how this is possible that the unit is locking out the cooling. Don't have access to HVAC Partners yet, hoping someone can get me the literature for this unit, or share a similar experience.

Cheers.

[Dallas Duster]

Does it have a variable speed drive on it ?
In the history do the alarms happen at the same time or somewhat close?

[wolfdog]

http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/48_50a-6t.pdf


http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/48_50a-1t.pdf

Or go here, hit literature,search, and help yourself.
http://www.commercial.carrier.com/commercial/hvac/homepage/1,3052,CLI1_DIV12_ETI372,00.html

[Entity]

Thanks Wolfdog, I tried to use carriers site but was giving "search" too much information. I appreciate the help.

[Entity]

thegoodlistener, i have not been back to check when alarms happened, but supply fan is on a VFD, condenser fans are not. Have an idea?

[Dallas Duster]

It`s a airflow issue check in the configuration and see if the supply fan statys monitoring is set for none . I think the vfd is tripping off and that is the only other alarm that will trip the compressor unless it it extremely cold outside and in that case it should be economizing.

[Entity]

TGL, thanks for the input, i will check that out. Cheers.

[DBSLLC]

If the units have ABB drives, the keypads have been going bad. The new keypads have a gold or silver edge.
Check power connections at VFD also. Some loosed up.
The algos look for change of flow by looking for increasing pressure differential at the transducer. Previous post is correct to turn off fan status since on a hot start (Monday morning the static pressure may not climb fast enough.