I have a 2007 Chevrolet Equinox and had my cluster repaired for the temp gauge. Now it works but will not drop the entire way after it cools down. I was told that this is a temp problem with GM vehicles and not the temp gauge...is this true ...is there an ongoing problem with the temp gauges not working in these vehicles.

Unlikely to be the battery, but they can be checked very easily.

you need a good auto electrician with a pro grade scan tool computer to diagnose all the electrics.

https://www.google.com/search?q=auto+electrician+near+me&

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Question edited for year make model.
Question moved to sub category.

It is a known fault on that model.

https://www.google.com/search?q=2007+chevy+equinox+gauges+not+working

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Early and mid 2000 GM Trucks have a instrument cluster issue, think the cluster is your problem and the unit will have to be repaired or replaced.

I know that you can't trust the Trailblazer instrument cluster at all. Our 2007 was the biggest mess, but it's the gauge clusters and not the sending units that are defective. There are Good Folks making a Living doing nothing more than rebuilding Trailblazer Instrument Clusters and you can google that. The only way to know for sure is to verify with other means. For example, For MPH on the speedometer simply drive an indicated 60 mph on any Interstate Hwy that has Mile markers and time how long in seconds it takes to get from one marker to the next. 60 seconds means the speedometer is perfect. A temperature gun can tell you if the temp gauge is working right or not. Is your mileage changing or are the gauges giving you bad info? My advice is start at the gauges because they will drive you nuts. I hope that helps you!

These codes have nothing to do with instrument cluster !
DTC P0420: Catalyst System Low Efficiency Bank 1 , Catalytic coverter is bad ,
DTC P0496: Evaporative Emission System Flow During Non-Purge
Evap emissions purge solenoid is bad more then likely . Your best bet , take it back to where you got it .

Check for possible air in coolant system

when a temp gauge drops to cold ,it indicates a problem in the cooling system
temp gauge sender units need water to activate the resistance that makes the gauge read so a falling gauge indicates no water around the sender unit --- air lock in the system--faulty wire connection to the gauge sender unit
the ac unit is not connected to the temp gauge so there may be another separate problem there
the temp sensor is an entirely different unit to the temp gauge sender unit and the short term working would be from an altered coolant level from changing that sensor --air lock in system
the temp sensor connects to the ECM to activate the fans and monitor engine operating temp so as to keep the air/fuel mixture exact for the engine conditions
the temp sender unit just makes the temp gauge read
a faulty thermostat will either be stuck open and the engine temp will take a long time to rise or it will be stuck closed and that will cause an overheat very quickly

Cluster is going bad it's a common problem

Its probably the gage itself. A quick stop by a Dealership and they can check the instrument cluster gage by gage. For free maybe! If not the gage, could be the engine temperature sensor.
As long as the engine is NOT overheating, you can still drive it.

try replacing the coolant temp sensor, if that doesnt repair it then may have a bad cluster or the wiring to sensor, try connecting two terminals together gauge should drop . hope this is helpful,