I have the red triangle symbol lit up what does this mean?

Fault

Red light lit on freezer means that is not reaches operating temperature.

Most often the old freezer has three indicator lights.
- Green light : that it is brought to a power source and turned on - Red light : means that the temperature is above -18 degrees
- orange light : pressing the so-called SUPER-switch which means that the compressor is running continuously. The SUPER-button switch on a few hours before you begin deep-freeze foods. Freezing time depending on foods quantity (kg). With old freezer must be careful to turn off the switch S (orange light) when the red light goes out or when foods are frozen, otherwise after a few days may burn out the compressor. You should be following the instructions from user manual.
In new freezer managed by the electronics, this function has a predetermined maximum duration, in order to protect the compressor, and can have different marketing names like "shopping".....

Dado

Good Morning Jon, this is Z. Thank you for allowing me to assist you!

I see that your post is listed under Frigidaire freezers. Please help me understand if the question you are asking is related to the "UP" and "DOWN" arrows that are designed to change the temperature setting? If you are speaking about another triangle symbol, I will need your model number please. The serial tag, which lists your model number, is normally located inside the cabinet, on the left side wall. With this information I can better address the issue at hand. Thank you!

Under normal operating conditions, the internal
temperature of the freezer will ensure the longterm
conservation of the stored food.
When such temperature rises above a certain
level (-12 °C), the appliance will trigger an
acoustic and light alarm. The light alarm is a
blink red light (Red Alarm Indicator Light), while
the acoustic alarm is an intermittent sound.
You can stop the acoustic alarm by pressing
the Acoustic Signal Stop Switch once.
When switching on the freezer for the first
time, the Red Alarm Indicator Light will
blink until the internal temperature has reached
a level required for the safe conservation of frozen
food.

Dado

It's a temperature warning that the freezer is no longer at the correct temperature. Check all is clean and working, door seal intact etc. If short of gas, probably time to get a new one!!! Bet it won't last 18 years this time though!

Is all ok now?

you need to clean the condensor coils with a brush or compressed air

its too warm,could be iced up or worse.

two reds and green are the auto max freeze on indecators the reds go off one at a time when unit drops to safe temp mode.also means unit needs defrosting manually when too much ice is present.

Is your circulating fan working?
Sometimes they stick and need a shot of WD 40 and then work
it back and forth a little until it wants to take off again. Keep me informed
and PLEASE give a Thumbs Up for the effort. The Raz Shack