Odd Goodman Package Unit Problem

airwick

hey folks,
HVAC in not my expertise so I figured see if you guys down the hall here had any insights. I have a Goodman 2 ton PGB Series packaged unit (natural gas heat) on a house. The unit works fine during the day but won't cool at night. It has a programmable thermostat, so the first thing I did was swap that out for a new simple mechanical unit. The tenant says at night, with the unit set to 72 (they never adjust this setting) the unit will shut off and stop cooling. The unit does not move air at this time either, so the fan is not running. Come morning, the unit starts working again and during the hottest part of the day, the unit cools just fine. Come night time again around 2am, they say it gets up to about 80 in the room (Yes, the thermostat and the main return are both in this room and the interior doors are left wide open allowing for proper airflow through the house.)
You guys have any suggestions?
Regards
Eric

We Fix Houses

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flashheatingand

The timing issue sounds wierd. The best thing to do is show up at night when the system fails. One thing you can do is to jumper the r&y terminals (low voltage) during the evening, and follow up the next day. By jumpering the terminals, you are by-passing the thermostat circuit. If the system still fails during the night, you know the problem lies somewhere in the unit. It could be a control board issue. But who really knows, at least, if you run this test, you will save someones time with the diagnostics.

mdshunk

Yeah! The system is probably low on gas. At night, when it cools a bit, the pressures drop accordingly. It's probably shutting down on the low pressure safety, to keep from toasting the compressor, then when the sun comes up and pressures rise, you're running again. Did you put a set of gauges on it?