[jagplates]

When you have a dead battery, it screws up the calibration of the A/C control system. (For some reason, disconnecting the battery usually does not cause the problem, but a low or dead battery does.)
In order to recalibrate, this is the process for a 1998:

CALIBRATION/DIAGNOSTICS TEST ENTRY
TO INITIATE TESTS:

* Set Blower motor ON HIGH
* Set Mode position to Panel
* Open all A/C outlets
* Set Temperature to Cold (Both slide pots if equipped)
* Depress WASH and REAR WIPER button simultaneously for 5 Seconds (Until all LED's light)

RESULTS:

* All LED's will turn on for 5 Seconds
* Calibration Test is running when REAR WIPER and INTERMITTENT are alternately flashing. Cool-down test is running if A/C and RECIRC are alternately flashing.
* Acceptable result is REAR WIPER LED is the only LED flashing. Push Rear Wiper to exit.

That should do it. If not, post again and we will try to help.