Batboard

My vhf maxtrac that is mounted in my vehicle
acts strange when it gets cold (below 35F).
The radio when receiving a signal will sound
a low tone and then basically lock up on me.
It takes a while for it to recover after turning it off. When it locks up you can't
change channels etc and it seems to always
revert to channel 25. I really could use some
help with this one. Thanks.

Take the radio apart and unplug then replug EVERYTHING in it with a connector. This includes boards, plugs, ribbon cables- ALL.
Check the VCO area for any loose inductors. The Radius/Max/GM family is famous for things like this. It's possible the VCO is just on the edge of being out of adjustment and when things expand/contract, it goes off.
It could also be a solder joint. Get it on the bench and use a component cooler to isolate.