AC sometimes does not go on even though controls are set to on. Noticed that the little slit light above AC push button on dash does not light up when this happens. Other lights above other buttons OK. Sometimes this condition lasts for 20 min., other times lasts for hours. Is some electrical part ( relay?) going bad. Please give any advice you can on how to solve. Is bad part accessible or does whole instrument panel have to be taken apart?

Thanks

 

Have your A/C system pressure checked. May need to be charged.