Hi Everyone!
I am having issues with my Jeep Liberty 2002 (4 Cyl.) They started a while back when the A/C fan level 2 stopped working. Then central locking stopped working (I can unlock the whole car, but locking doesn’t work at all! not through the button in the car, nor through the remote). And finally yesterday, A/C fan level 3 stopped working. Are these related to fuses? what should I look for?
Help please! 
Giving advice concerning Jeeps is not my forte, but your first question is an easy one to answer.
You need to replace the blower motor resistor block to fix the fan speed problem.
If you are mechanically inclined with a few everyday tools, you can replace this yourself.
The block is usually attached to or is located close to the blower motor and in most vehicles (I don’t know about Jeep) is located below and behind the glove box.
If not, I’d advise you to locate a reputable independent tech/shop as the job will be done without them telling you (like some dealers) you also need fresh air in your tires for $xx.
In regard to the faulty power door locks, because the doors UNlock but do not lock tells me it’s not a fuse problem.
I’m going to suggest there MAY be a faulty power door lock switch involved and/or the power door lock/unlock mode needs reprogramming. I think your owners manual explains how to do this.
The only other possibility I can think of would be the security system in the vehicle needs to be checked out. Sorry, I can’t do better here.
There may be a broken wire in the door jamb causing the lock problem. If it is, the small wire harness section for the door is replaceable.