I have a 2001 nissan p/u that the starter will not click or spin when near freezing, ok when warm.

So it pops under the hood once each time you try to start it / each time you turn the key from "on" to "start"? If so, take a set of jumper cables and use just one of the cables, attach one to the negative battery terminal and the other end to a bolt or bracket (something steel - not aluminum / dirty cast) and then try to start it. If it spins the starter, then you have a ground issue from either the neg battery to the body of your p/u or from the p/u body to the engine. remove one bolt and clean the mating surfaces with a wire brush and add a dab of grease and then try to start. I just recommend that one bolt at a time so you know which one to keep an eye on later. Keep me posted please :)

You can also leave it in park / neutral, turn the key to on, remove the positive signal wire (small wire on the starter solenoid) and lay a screwdriver across from the starter signal to the main power for the starter. The main power to the starter comes straight from the positive battery cable. This acts as if you were trying to start the car from inside and will activate the solenoid and starter. If it pops loudly but doesn't activate the starter, you are hearing the drive gear being popped out to the flywheel and back to its resting place. You can also check the positive side by putting the jumper cable from the positive battery terminal and the other end on the large positive terminal on the starter to bypass the large cable. I would only check one system at a time (positive system or negative / ground system) to figure out which is the problem.

Just clean the dang connections and fit them tight at the battery. Inspect the cables well and verify good connections, volt drop test if they may be cheesed on the inside but look good on the outside... cant believe your "mechanic did not fix that symptom of discharged battery, when battery was ok, that's textbook connections and cables. No need to get the jumpers or the jaws o life or anything else.

Sounds like you need to get the battery load tested at an auto parts place or with a special meter. It could be getting near the end of it's usable life. http://www.forbes.com/sites/jimgorzelany/2013/01/22/did-your-car-start-this-morning/

A battery that fails to deliver when engine is cranked and then does deliver for another try, and temp affects it to stop the problem can be poorly connected, if the connections were "good" the battery was believed to be "good" The volt drop tests would be next. an intermittant open inside a battery can lead to an exploding battery. If it only acted up during a freeze, I would say cables and connections would get it started or get you going to buy parts, then you can try the "maybe", chinese, tester. An actual carbon pile would pull the required amps to truly perform a load test better. If they have one. A technician would have the carbon pile at a reputable shop. He could then perform the rest of the charging starting and loads and draws, cranking amps etc, the way they are required by every vehicle manufacturer before paying a warranty claim for related parts. why shouldn't you demand the same tests with the same equipment and get the complete diagnosis. They may need to charge the battery for a few, and while they are there, correct obvious neglect. and point things out that are about to cause other issues, like alternator belt, harness issues, poorly connected add ons, the whole picture. If you have extended coverage or mechanical breakdown insurance, they can call for you and say what needs to be said to get you coverage or participation. They can also run your vin and pull your file to get the Tsb or recall info that can speed up and more correctly address your issues.....or not. hey, you may have AAA and be too busy, who knows.