The freezer section of the fridge freezer in our garage works intermittently while the fridge section works well. Why?

Sometimes this can happen with fridges that have two evaporator circuits. One circuit controls the freezer and the other controls the chillier part. I can't be sure how your fridge has been configured but the first thing to do is defrost it.
Has the fridge been moved recently or tipped on its side? The compressor has a small amount of oil in it to help it run smoothly and prolong its life. If any of this oil finds its way into the gas circuit it can restrict the calibrated evaporator jet. Defrost the fridge and let it stand for 12 hrs. before restarting it.
This problem can also point to an old and worn out fridge or a fridge that requires re-gassing. Either way its best to buy a new fridge in this case, you can generally tell as the fridge motor will run almost continually and get very, very hot indeed and can become a fire risk.
Lastly, some people put fridges out in a cold garage or store. This can also prevent some fridges from working properly when the garage temperature drops below the temperature that the fridge operates at, it this case the freezer part might also stop working if the temperature of the garage dropped below freezing.
So, Defrost your fridge and let it stand for a while at normal room temperature. Restart the fridge and it should work normally. make sure the temperature dial is set to a reasonable setting, it should work, if not it might be time for a new one.

Empty fridge and if possible put steam down vent behind the cover in the freezer section. or hot water. it will com out in the fridge so be carefull. this unblocks the aif feed from the freezer to the fridge section. also make sure the fan is working.

The problem is with the garage temperature. The temperature sensor for the refrigerator is in the fridge compartment, but the evap coils are in the freezer. Refrigerators were designed to work in an air conditioned space. When they are put into unheated spaces, it does not work well. The fridge thermostat typically is set to 40 deg F. If the outside temperature is close to that, then it does not turn on the compressor as much so the freezer will have a hard time staying below freezing.

There are garage refrigerator kits for people who put fridges in un heated garages in the winter. They just simple electric heaters that warm the fridge's thermostat to cause the compressor to run more often. This helps the fridge to maintain temperatures better in the freezer compartment. The same thing can be accomplished by putting a small wattage bulb in the refrigerator compartment. Just remember to remove it during the warm weather otherwise you will pay a large electricity bill in the summer months.

It could be a problem depending on how cold your garage gets in the winter. Most refrigerators depend on the compressor turning on to cool the freezer section and that cold air is used to cool the refrigerator section. If your the temperature in your garage gets in the 30-40 degree range in the winter. The compressor may not turn on sufficiently since the refrigerator is typically around the 35-40 degree range. This will cause the freezer to warm up to the fridge temperature and your freezer items will defrost.

the freezer takes first priority for cooling,then the fridge,the unit will take about 24 hours to reach optimum cooling even with the fast freeze button on.we used to have unit in garage with power on to unit permanently.using a power breaker in case of shorts etc......(f/f are supposed to be on permanently)

Since refrigerators were designed to run in your 72° kitchen, when you put a fridge outside, where its colder than normal operating REFRIGERATOR temperatures, i.e. 35-40°F, because that ambient temp is colder than fridge temp, the thermostat in the fridge section reads it as normal temperature, and does not turn unit on. it does not read what the freezer temp is. You have a couple of choices: bring the unit inside, heat your garage, or only use it for pop and beer in the summer. You can reply here or send me a question from my website: www.FixMyFridge.net

I'll assume you don't have much food/items in the freezer section. Because you have the fridge set on the max cooling setting and the freezer set higher than the mid setting, it could be that you have frozen the cold air passage from the freezer to the fridge.

If you can, 1) remove all contents that would spoil; 2) turn off the fridge 3) open both doors and allow the fridge to manually thaw out completely (this will speed up the opening of the cold air exchange passage between the freezer and fridge, which is likely blocked and frozen solid. Have plenty of towels handy to soak up the water from the defrosting process,

After a FULL day of being left off and doors open to thaw out, check for any further thawing and dripping water inside, if present wait another 8 hours (you really want to get it thawed out the first time!) When that's done, reset BOTH temperature controls to the factory mid-point setting (5?) as marked on your control knobs.

The key to having a refridgerator run properly is to allow for it to run at the factory settings for at least 24 hours BEFORE you adjust the controls higher and/or lower for each section. Adjust it up or down in ONLY 1 setting increments so as to not cause ice build-up and freezing of the internal air exchange passages.

Also, as you've relegated this fridge as a garage "beer & backup" unit, make sure to keep the freezer as full as possible to make it run as efficiently as possible. You can freeze jugs of water and pack it with cheap thrift store bread to help it run correctly. An empty freezer has to work harder to keep just air at freezing temps. As such, it will pass much colder air into the fridge, and cause these types of freeze ups. By the way, turning up the temp controls only makes it worse and just results in a total "freeze up" inside the cabinet panels that you can't easily see or get at to rectify, hence the reason to shut it off and let it fully defrost.

When you're done, you should have your fridge back in action working like it should, but remember, don't rush temperature adjustments, even thou we all want those frosty beverages, it'll take a couple of days to achieve the desired "chill" you're likely used to getting when it was your primary fridge.

Hope this helps and Best Regards! Semper Fi!

Top mount refrigerator installed in a garage and the food in the freezer is defrosting when
the temperature in the garage goes below 55 degrees fahrenheit.
On top mount refrigerators you cycle the compressor and fan/fans from the food
compartment temperature. When the room temperature gets colder than 55 F, you have
long off times waiting for the food compartment to warm enough to trip the cold control.
This long off time is allowing the freezer temperature to get high enough that food can start
to defrost.
There is a kit for refrigerators installed in applications where the temperature can go as low
as 34 F and still maintain good freezer temperatures. The kit part number is 5303918301
and it contains a heater that mounts in the control box and an instruction sheet advising
how to install the heater.
Kit 5303918301 contains:
Part # 5303950194 Instruction sheet
Part # 241532101 Heater

Assuming you have a frost-free refigerator:
Is your motor-compressor running?
If so, check if you have ice in the freezer section; if so, maybe your defrost thermostat or heating element is kaput.
If the motor-compressor is not running, check in the back of the refrgerator if the defrost time is stuck open, bu turning clockwire the small test screw, with a 1/2inch screwdriver.