The blinking ECC display typically indicates that an issue has been detected by the ECC, and a code set.
A brief google discovered this thread on another board:
Automatic Climate Control - blink codes
I think you can for the 98...this is from the 99 service manual:
1. Press & hold the OFF, AUTO, and RECIRC buttons for 1 second.
2. the DTC'* will display for 2 seconds each and then return to normal operation.
There are 24 DTC'* listed in the manual ; 18 start with B; 6 start with U.
This may be worth a crack to try and get some answers. Have you noticed any other issues with the climate controls?
Also, when you attempt this, make sure you are able to record the codes when you do it, as it was suggested that doing this causes the ECC to dump the stored codes.