Did not recharge A/C after changing timing belt

Most Chrysler electric radiator fans turn on at 210 degrees and off at 198 degrees.

There are two concerns with running around with no refrigerant. The first has to do with winter driving. The AC compressor is supposed to run in "defrost" mode. That is to condense out the humidity from the incoming air so it will not condense on the cold windshield and cause fogging.

The second issue relates to air getting into the system. When the system is opened, air gets in and brings its humidity with it. Water mixed with refrigerant forms an acid that attacks the metal parts. We always pump the system into a vacuum just before adding the measured amount of refrigerant. Under a vacuum, water boils at 77 degrees. The resulting vapor is easy to draw out with the vacuum pump.

When enough refrigerant leaks out that the pressure is below a set point, the low-pressure cutout switch prevents the compressor from running so it cannot pull the low side into a vacuum. If it could get it into a vacuum, air could get sucked in along with its humidity. When you have no refrigerant at all, the compressor will never turn on, so there is no danger of pulling the low side into a vacuum, however, you have to consider changes in barometric pressure. If that goes up overnight, in effect, that puts the AC system in a vacuum. Once again, you have the chance of air and humidity sneaking in.

If you add refrigerant without drawing the system into a vacuum first for at least a half hour, any water is supposed to be captured and stored in the receiver/drier, but there is a limit on how much water it can hold. When a droplet circulates with the refrigerant, besides the corrosion issue, it will freeze and block flow at the expansion valve where the pressure and temperature drop a lot. It can take up to an hour for that ice to melt, then the refrigerant will flow again, and cooling will occur, until the next time that drop of water gets to the valve. If no air has been allowed to enter the system so far, you can add a small amount of refrigerant to keep it under a little pressure. That way no air will enter when barometric pressure goes up.