Fan motor over heating & Shuting down.

[Rookie]

I recently tried to fire up my home Central AC unit for the first time this year (and older Heil solid state model CU 325BQD1C) and after approximately 3 minutes of cooling the fan motor stopped running, and the unit shut down. This unit had been installed by my father in law (no longer with us). The unit has had a history of needing to be recharged every few years but no big deal. So ... figuring this being the problem, I called in the heating and AC Tech, he verified the unit was slow on coolant and proceeded to recharge it. After completing the recharge shortly thereafter the fan kicked out and the compressor went (as the tech said) "by pass" (I assume this is a protective function of the compressor). He said I'd need a new fan motor .. well being fairly knowledgeable (but not in no means a heating Air conditioning tech ... but that's why I'm asking) I decided to pay the current bill, and tackle the motor replacement my self. 1/4 HP, 2.0 FLA 1/2 shaft 230 volts cap start ... no big deal! So I went to the local Grainger store, got my company discount, (I bought had stuff from them in the past) and proceeded to install the new motor.

After the installation, I proceeded to fire it up. The results were the same ... unit started to cool, but after about four to five minutes, fan slowed and turned off (over heated.. hot to the touch) and eventually the compressor turned off.

After all of the above ... i have a few questions

1) What is the function of the solid state sensor located in the fan tunnel (by the condensor coils)? (One of the leads from the fan motor are attached to it)

2) What direction should the fan be operating? I currently having it pulling the out side air through the coils.

I hope I provided you with all the pertinent info needed to help me with this issue. Or if anyone has any ideas (other then replacing this dinosaur) they would be greatly appreciated.

Thanks in advance,

A Rookie