Your problems is very similar to an electrical issue I just had on my dad's van. Same fuse was blowing (15amp) in the junction box. Some days it would run fine, while others the fuse would blow as soon as the ignition was turned on. You have a short somewhere blowing that fuse. I purchased a resettable blade fuse -and this helped in troubleshooting the issue as I could reset and disconnect and test when the problem happened. If its related to temp, let warm up in your driveway.?My issue turned out to be an exposed wire that would ground when going over bumps or when there was vibration causing it to short.
