Our Frigidaire FDG4 model dryer does not heat up completely. It gets warm, but does not get hot. Any suggestions?

Gas or electric? Always check the vent to make sure air flow is present. Some older electric dryers use 2 elements and 1 could have burned out.

Gas or electric? Always check the vent to make sure air flow is present. Some older electric dryers use 2 elements and 1 could have burned out.

This dryer is gas...

I'd start with a vent and lint filter check.

I'd start with a vent and lint filter check.

Vent and lint filter are clear...

It may look clean where you have the filter, but you go by age and the amount of clothes you launder. When it gets dirty the sensors will not know how hot it is in the air since the sides of the duct where they are attached are insulated with a layer of concrete-like (and very flammable) lint deposits. You will have to clean the drier out thoroughly. Every air duct will have to be removed and scraped and washed out to remove baked on lint deposits which is like a concrete lining. This will burn so the manufacturer has installed the safeties to keep from having a house fire. Driers were the number one cause of fires at one time. For a video to help, look at: How to clean your clothes dryer. How to make it hot again. - YouTube (http://www.youtube.com/watch?v=MMP7BW1lLs4) to see how. Also: Mr. Appliance Tips: How to Clean Your Dryer - YouTube (http://www.youtube.com/watch?v=iBiRw-KElC4) ; Cleaning a Dryer Vent and Lint Trap - YouTube (http://www.youtube.com/watch?v=yFTZGgVisCI)
When you finish cleaning the drier it is best to also replace the belt, too, because you do not want to have to disassemble it again, and if the belt is over two years old you should replace it. Also, you need to lubricate the bearings with white lithium grease. EVERY bearing you find should be lubricated. That means the support rollers and the center drum bearing, if it has one.

Note that on most of the videos it does not show them washing out the parts, but this is important because it's the only way to really get the parts clean, just don't get motor wet or the capacitor if it has one. Vacuum out the motor. I would move the drier out to your garage to have plenty of space to work. You also want to check your vent and clean it, also. The job is really easier than it sounds. There is no shortcut that will work; it has to be cleaned well. Just vacuuming out the dryer a little does little good. When you are done you will have a new dryer and it will dry like new again. You want to clean it like this every two years or every year with many children.
On a gas dryer you may want to clean the flame rod with some fine sandpaper. It's a small platinum rod that looks like a spark plug and proves the pilot light is lit. It takes a few seconds to do, but will save you trouble later. Good luck and attached are some manuals: https://dl.dropboxusercontent.com/u/8010163/Frigidaire%20Dryers%20and%20Test%20Equipment.zip

Tim, if all is clean and clear I would check the thermostat, temp control located in the blower housing. You never posted the complete model #. Good luck

You could jump it out with a short wire to test it. That's only for a test.

tim, if all is clean and clear I would check the thermostat, temp control located in the blower housing. You never posted the complete model #. good luck

you could jump it out with a short wire to test it. that's only for a test.

First, thank you for all of your help. I truly appreciate it. Second, the full model # is FDG436RES1 (it's possible that the G is a 6 too. I have a tester that I'll use tomorrow. Thanks sgain.

Make sure to clean it before testing or the tests are meaningless.