This item is interesting. Do you like it, and is it working for you?
Can you unplug this unit? Then plug it back in. Have you tried this to see if it clears the blinking PL?
I didn't see anywhere in the owners manual that specifically said what PL means, but I did find this,
"Stop the air conditioner immediately if one of the following malfunctions occur:
1. The operation indicator or other indicator flashes (5 times per second) and the
flashing does not stop by disconnecting the power and then connecting it again."
If unplugging and plugging it back in doesn't clear the flashing PL, then you need to either go into Sutherlands to see if any of them have experience with this particular item, or call the Frigidaire company (recommended), 1.***-***-****, to see what they recommend.
I would also suggest that you bookmark this owners manual for future reference in understanding the operation of your product: http://manuals.frigidaire.com/prodinfo_pdf/Edison/66129905600en.pdf
I found the above information on p. 25 of the owners manual, and the phone number on the last page. I hope this helps. Let me know.
If you feel I addressed your concerns, please be so kind as to rate my answer with positive feedback; this is the only way I receive recognition from the site for my assistance. Thank you very much!
By providing a positive rating will not end our conversation, should you need me for any follow-up. Simply click 'Reply' for clarification or additional information, if needed, and I will be happy to continue. There is no additional charge for follow-ups.