Yes, sounds low on charge. If you're experiencing cool nights and warm days, it will cool intermittently. Also, sometimes if you pump it down, you've backed up the refrigerant and it may work normally for awhile until the ambient drops. If it were me, I'd add a little gas. Your sight glass will clear once the headmaster kicks in. Make sure it operates correctly. Find and repair the leak. Charge the unit properly. There is a Sporlan document floating around this site on proper headmaster charging.