climate control flashing

I have a 1999 4runner limited with about 185k miles. For about the last 6 months (I've procrastinated) when I turn on the ignition, the climate control attempts to boot up but will sometimes flash on and off and not work until I turn the key off then immediately back on. When that doesn't work I can hold the "off" and "mode" buttons under the display at the same time which works after a few minutes. Now and then it boots up properly and is fine but the problem is not predicable.



Any wizards out there with a suggestion /diagnosis?



Thanks in advance for your time.