With an American standard variable speed air handler, does the motor circulate air at a lower speed continuously when compressor not in use

High and low voltage AT the motor with no motor function is a bad motor. Should have 12 to 13 volts DC on r+ and r- (I believe are the correct terminals) You must test this when the machine is trying to run. Yes, it's dangerous, hire a licensed contractor!!

Yes, all manufactures are using the dreaded X13 ECM motor. If you can get a tech to do so replace it with a single speed motor and add a relay

Variable motors are used on select Goodman EVAP AIR HANDLERS. What model do you have?

Possibilities:
A: If the compressor turns off but the circulation fan continues:

1. Insufficient refrigerant charge;
2. Refrigerant overcharge, causing evaporator coil freeze-over;
3. Defective compressor clutch;
4. Clogged screen in orifice tube;
5. Front condenser coil is clogged with dead bugs, dirt, foliage, or other material.

B: If the entire system turns off, including the circulation fan:

1. Defective system breaker;
2. Defective system relay;
3. Defective climate control module (at dashboard);
4. Fan motor overheating due to clogged air intake or other obstruction;
5. Fan motor overheating due to debris in air handler box, such as leaves or other plant debris.

Some companies do sell a variable speed kit. It includes the motor and controls. Get your model and serial number of your unit and contact your local Payne dealer. The can locate the proper kit if available for you.

most have a run capacitor. replace that.

They are expensive to buy, and to replace it as well. I would not to expensive. Any air handler, just not a variable speed.

Air Handlers differ in the way they adjust there variable speeds. Carrier you just plug into a pin. Trane has dip switches with directions on the fan housing. Before you try to adjust please kill power to air handler. Varriable speed are very sensative to voltage. If I new your air handler brand I could help. But just check the wiring diagram and they may ahve dirrections on there for setting speed. Need more help call back Rus

If your outdoor fan is a vertical discharge in other words if the fan blows the air up from the top of the unit then one foot from house is fine, but if it is horizontal discharge or blows it out the side then the airflow needs to be directed away from the house or the unit needs to be moved away from the house far enough that it doesn’t restrict the airflow.
For the blower running on high speed a 4 ton unit is usually 1600 cfm so on low cfm it may seem like high speed. There should be some speed taps on the indoor pc board and if you look in your installation guide it should tell you what taps you need to get the lower airflow if its not correct.
For the luke warm air in the 2 ton mode, the coil is a still 4 tons but the compressor now is only pumping 2 tons of refrigerant so the discharge temperature and head pressure will be much lower and that is what determines how much heat you get, so you will get less heat. The 2 ton mode is for times when you only need a little heat or cool, when you need more then you will get the 2nd stage which is the full 4 tons of heat.

i dont think so that variable speed air handler is a nightmare when(not if) that motor goes bad its 700.00 to 900.00 the regular 3 speed one your getting 125.00 and it will last 10 to 15 years ....... if you realy want fun install a 17 seer system ,you will have your repair guy on speed dial