Reduce level of vehicle heater/cooler as its now too much after 1-second turns

[ghost]

Summary

SUMMARY: Bugfixes "Reduce level of vehicle heater/cooler as its now too much after 1-second turns"

Purpose of change

As above

Describe the solution

Reduce the field from hotair3 to hotair2.

Now the tile with the heater and the tiles around it go from 8c to 17-20c instead of up to 40-50c

Describe alternatives you've considered

N/A

Testing

Spawned vehicle, installed heater, turned on temperature overlay, saw that it was now hovering around 17c to 20c from ambient of 8c

Did the same for cooler and saw that it too had dropped temperature byu around 10c

Additional context

N/A

[kevingranade]

This pull request has been mentioned on Cataclysm: Dark Days Ahead. There might be relevant details there:

https://discourse.cataclysmdda.org/t/vehicle-mounted-heaters-broken/23312/5