Blower starts up, while climate control turned off

[JSNMV]

Hello, I have a unusual situation with my 1986 300 SDL. While the climate control is turned of (right button depressed) the blower fan starts on its own, and blows air at whatever temp the temp controller is set at. You can hear a relay kicking in and out near the pass. side panel below glove box. My questions are, which relay is this? Is the relay at fault or is it recieving a signal to start fan from another component? I should also mention that if the fan starts erroneously, I can push the "off" button again and the fan will stop, but its just a matter of time before the fan will restart again. Thank you all for your suggestions, today and always. Jim