That is generally not recommended:
1. The temp ratings for indoor APs are not usually capable of supporting the outdoor environmental conitions AND the solar loading (if placed in direct sun). As such, the lifetime of the AP can be dramatically lessened and warranty will not be honored.
2. Indoor APs run at much lower maximum power settings, and higher power level support is often required for outdoor deployments.
3. Placing something like an AP-103 into an enclosure will decrease overall Tx/Rx by 3dB or more due to attenuation of the enclosure. Using indoor APs with external antennas may lose the attenuation from the enclosure, but will suffer the same kinds of loss due to the addition of the extra bulkhead connectors and extra antenna cables (plus the RF loss due to the diplexors).
4. In general, the cost of purchasing an outdoor enclosure, the accessories to install it and support an AP inside it, and the MUCH larger cost of labor to install and weatherize, will at best match if not exceed the cost of something like an AP-275.
Our outdoor 3x3 11ac will outperform any indoor-deployed-outdoors 2x2 11n option in both range, throughput, and temperature support.