Fbody Locks

Hey yall im just wondering if any of yall with a 93 or earlier mustang have had troubles with the locks in cold wheather? My car is very hot/ cold when it comes to this. Some days when it is 10 or 15 degrees outside the doors open without a problem and other days when it is 20 degrees they or frozen shut. Im wondering if it has to anything with the fact that this was an arizona car for most of its life. (maybe the seals or something are dried up). I have tried about 50 dollars worth of lubricants, de icers and so on. Ive used heat guns and hair dryers and i still cant get my doors to open consistenly. Should i just get heavy duty remote door poppers(like what they use on custom rods with no handles) or should i replace the locks altogether?