Changing your transmission filter will help in improving the slipping under load.
The transmission filter is located under the transmission on a 2002 Hyundai Sonata. it is under the transmission drain pan.
The filter is on the top of the transmission under the hood and unscrew just like an oil filter
Transmission filter is usually under the transmission oil pan. If the vehicle does not have a transmission pan then it is probably a "non-serviceable" transmission, and it probably doesn't have a servicable filter.
Depending on the weight your towing the transmission may not be strong enough to bear the weight difference. Check your owners manual for towing weight limits. If your towing within the weight limit and your transmission is slipping, flush your transmission fluid and replace with new transmission fluid and change transmission filter.
Inside the transmission under the pan.
Its located under the air filter box almost under the battery.
There is no mileage where one "has" to change the transmission fluid or filter. It is your car and you can do with it as you wish. The warranty manual for my 2000 Forester recommends changing the fluid every 15,000 miles when used under severe conditions. I recommend changing ATF yearly and you shouldn't need to change the filter unless it has been damaged. It is as easy as changing the engine oil, so why not do a little preventive maintenance? --Ken
Inside the transmission under the pan.
Right under the air filter
From my research, 2003 and before has a spin on filter under the hood and a non serviceable filter inside the transmission. 2004 and up, has just the internal filter. The internal filter requires transmission removal and disassembly to access.
The transmission filter is located in the bottom of the transmission under the oil pan. You have to drop the oil pan to access it but the filter should come with a new gasket.
yes under the floor