A/C only works on high...Why?

There are 2 likely causes, the fan switch is bad or the blower motor resistor is going bad. The easiest to replace is the blower resistor it is behind the glove box near the blower motor. This is what I would try first. If that doesn't fix it I would try the switch there is a diagnostic chart for the switch in the service manual at the link below. If you need it there is a very detailed service manual for the Camry's at www.camrystuff.com And best of all it's free!