I have a 2002 Toyota Echo. The air from the a/c is not cool. I took it to have it check out by an A/C mechanic. First, I was tol that it had too much freon. (The low side gauge indicated over 70 psi). The excess freon was removed and it seemed that the a/c started to work "ok."
But the mechanic recommended to removed all the old freon completely and recharge the system with the right amount, so he did. He also mention that the compressor may have some damage because of the previous overfill.
Now, the compressor is working when turned on, but again the air is not cool. Now I was told to replace the compressor and also the expansion valve which may be stuck. Total cost: $1500
My question before spending the money, does it seem right what I was told or it can be something else not that expensive? If it is what I was told, $1500 seems like a reasonable price or its too inflated?
I will appreciate the help of an expert. Thank you.

First: Agree that the system should be completely evacuated and recharged to the proper amount.
If after that, the pressure gauge goes negatively low on the low pressure side, then that would indicate a stuck expansion valve.
If the needles vibrate on both the gauges, then that would indicate a faulty compressor.
I would like to hear you went for a second opinion for this. Cost can add up quickly for wrongful ac diagnosis.
If you trust this guy, then do the expansion valve and receiver drier first and hold off on the most expensive part. It's not a very difficult job on a Echo. Tell him to also check the heater control valve to make sure it's fully off on max cold position.

Here are several links that you may find informative and provide background information:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-9.html#post1864159

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-9.html#post1722090

Compressors often need to be replaced every 100,000 miles. On your car, I would replace the compressor, TXV, and dryer, if you feel you're a candidate. I'd recommend that you take it to Toyota.

If you need a new compressor, have them use BG Universal Frigi-Quiet Refrigerant Oil (Part No. 7018). Very good stuff.