Recently, my '96 Platinum Wagon started having an issue where the Electronic Climate Control (ECC) system would blink the REC and AC lights for 20 seconds whenever I turned on the blower motor. With my car being strictly an OBD-II model (no engine compartment diagnostic connectors like on '95 and earlier models), I figured that I'd have to use my scan tool (OTC Genisys) to retrieve the ECC codes. As I found out from a good buddy who worked at a Volvo dealership in the 90's, the ECC codes on '96 and '97 models can be retrieved via the OBD-II connector using the "blink method" with an easily-constructed blink code reader tool. Good thing too, because my Genisys refused to 'talk' to the ECC module on my car (weird, the Genisys worked on a '00 V70 XC ECC module).
To make the tool - only a few parts are needed. A 12-volt LED, a "momentary on" push-button switch (single pole, single throw), some female spade crimp connectors, some fork crimp connectors, and some wire (I used 14ga). Attached is the wire diagram that I created of my blink code reader tool.
My car had code 417 in the ECC module's fault code memory. Code 417 means: passenger side temperature sensor inlet fan seized. On these cars, there are two temperature sensors in the passenger compartment. They are located behind the grab handles above the front passenger and driver. Each sensor has a little fan that blows cabin compartment air past a thermistor and this is how the ECC system figures out the temperature on the driver and passenger sides of the vehicle. These fans start getting a build up of lint and dust over time, and could eventually cause the fan motor to seize. In my case, a few quick blasts of canned compressed air cleared up the fan blade and allowed the sensor to work again. Here's the video to my repair.
Lastly, I've attached a .pdf with a list of the various ECC codes.
I hope this information is helpful!
