heater goes on and off randomly

I have a 97 Aurora and I have had no other electrical or major issues with the car. However randomly the blower goes on and off. It does it on all the settings, and wether it is on AC or heat. It is really starting to bug me but its almost time to put it away for the winter and I would like to have it ready for "constant" cold AC this spring. I have tried tapping on the motor and it makes no difference. The temp flashes on the climate control all the time but it has always done this. Any ideas to what the random on/off issue could be? It is not throwing any body codes, just the usual o2 sensor in the engine. Thanks in advance

If the temp flashes, chances are there is a code set in the control head....never worked on Aurora's, so maybe someone can chime in on how to manually push the buttons on the control head to read codes...

This an auto system?

It is an auto system. However it only has 2 knobs, one for the position, and one for the fan speed. The temp set is an up/down button set under the temp

I remember on Buick auto temp systems, they had a temp symbol and when it flashed, there was a code set in the head.....you would press the off and warm buttons at the same time to get into diagnostics....and in some cases, there was a "hidden" button on the touch panel, that accessed it.....

I will have to play with the buttons and see if I can get something to happen. I have a 1997 Motor GM service manual the is super in depth and I have learned alot about the car, but still no real help for this situation. The same for Mitchell programing we use at the shop...