City multi pqry-p96tgmu 1500 alarm overcharge

[Shreadhead]

I was wondering if someone can point me in the correct direction. I am receiving 1500 alarms onoccassion. The unit never seems to lockout on this alarm but it will show up consistently. I tried replacing discharge thermistor with known to be good thermistor and the problem persisted. The literature only states that unit is overcharged or there is a problem with thermistor or input circuit on board. I set up maintenance tool for several hours and monitored discharge temperature and saturated high side temperature but was unable to catch the problem occurring. Tech support unavailable, I am awaiting training. Would the next step be leave computer on monitor mode for a day? Could it be solenoids or lev? Thank you.

[al]

You need to get gauges on it and monitor pressures, could be a faulty pressure transducer or a refrigerant related issue, or poor condenser fan control. Is it happening in heating or cooling? Full load or part load, random times of day?

[Shreadhead]

You need to get gauges on it and monitor pressures, could be a faulty pressure transducer or a refrigerant related issue, or poor condenser fan control. Is it happening in heating or cooling? Full load or part load, random times of day?

I will verify readings with guages and temp sensor. Unknown whether it happens in heating or cooling, maybe I need to leave computer on for a day or more to catch what happened at time of fault. Unit is water cooled and shares water loop with many other units, so that’s the one thing I think is safe to say not an issue.

[al]

Have you verified correct flow at all times on water loop? I'd start there funnily enough:))

[Shreadhead]

Have you verified correct flow at all times on water loop? I'd start there funnily enough:))

I have not, that's a good call. Unit is tied into the same loop as all the others, but it is the first unit that gets picked up by the return piping, so maybe it suffers being end of the line. I'll also have to purchase wet manometer and verify proper setting of flow balancing valve I suppose. Maybe check the strainer too. Thank you!