That's actually lower than most markups. I'm guessing you have R410a refrigerant, rather than R22 - you'd almost certainly pay more for R22.
You can look online and see the cylinders cost considerably less per pound, but you need to be EPA certified to buy them. With that price you pay per pound, you pay for the technician's technical knowledge and experience, and also liability, as well as your refrigerant. Compared to what I've been seeing HVAC techs charge for refrigerant, you actually seem to have gotten a pretty good deal.
You can find a Freon leak in a home Ac unit by using a leak detector. These instruments are capable of detecting trace amounts of Freon and pinpoint leaks.
4 pounds
It a word, no. Without a leak, the freon level in your unit should stay the same for years and years.
Yes you can if you have the tool, knowledge, and of course the freon. Youtube has instructional videos to help you.
$100
Depends on the size of the unit and when it was built. Modern A/C units contain no Freon (R12). It was banned in 1996. Call a home A/C professional.
it depends on the size of the unit and how many pounds of freon it takes r-22 is going for 10 to 15 dollars a pound
Either the t stat is way out of calibration or it is not level.
No easy way of doing this. These units do not come with service valves.
clean coil on outside and check freon levelstopped up coil will cause this problem
overcharging a central air unit system with refrigerant(freon) will cause the head pressure to be?
That depends on the size of the coils and the length of line in between.