Have two 8,000 BTU air conditioners both blow cold. With the fan speed set on high, the frigidaire barely blows the cold air.
The other model has a stronger fan output. I guess the Frigidaire has a defective fan?

Window AC's are pretty simple. Some units have a small filter in the front panel. Make sure it's clean. Check to see if the fan, a cage type blower is working. Remove the front panel, usually 4 screws and see if it is turning when it is on and calling for ac. You may be able to oil the fan too. However, if the unit is more than 7-8 years, get a new one, they are cheap and much more energy efficient.

And some brands do blow more than others, I bought one recently at a "big box store" on sale, it is not near as strong as the old one it replaced.

If the coil is dirty this is on outside and on the inside it can`t blow as much air,, if they can`t pull in enough air it won`t be able to blow out much air,, in most cases dirt,grime pet hair and dander are the biggest problem with window ac units