Blower defroster

Hello Everyone: Yesterday is the first time this happened. I put my defroster heater on the night before and it was working great, the next day I drove a bit and decided to put the defroster on, and Nothing happened, I keep trying to put it on with no success. I went into the place I was visiting and when I came out, I put the key into the ignition and turned it twice without starting the car, and the defroster/heater worked great again! I thought it was a fuse but a fuse would not work on and off!
What could be the problem? Maybe I should wait to see if it does it again first, but any idea's would be appreciated?
One thing I am doing that is new, and I dont know if this has anything to do with it or it is just a coincedence, but I am using a Power Inverter for my portable radio?tape player! Could that do something to cause this problem? Thanks, Tom

Could be ignition switch going bad. Defroster, wipers, anything that works when the key is on accessory all come off the same post on the ignition switch. If it happens again, see if others things have failed as well. Good luck! JWS

Well, it has not done it for long while now. But the air bag light keeps coming on at startup then it doesn't do it for a long time. Do you think that is connected?

It could be a relay going bad

Is the Relay something I could put in and are they expensive?

this isn't the exact one for your car of course, but this is what they look like.

http://www.partsamerica.com/ProductDetail.aspx?mfrcode=GPS&mfrpartnumber=415098&parttype=591&ptset=A

You can also have the parts store run the codes on your car, they might find something else.

I dont see the picture and I dont see my model plymouth acclaim??

here copy and paste if needed

http://www.partsamerica.com/PartTypes.aspx?pgid=RELAAMS&desc=Relays

but basically pop the hood, look around for a few small square plug in like fuses, there may be a few together, and there may be a cover over them, but the cover should say whic relays are beneath

Ok, Thanks, I will take a look and get back to you

Just checking in to see if you figured out the problem

I think I know what the relay switch looks like now, but let me tell you what happened the other day, I came out of Target store and went to start my car up and the ignition would not turn. I had to call AAA and they came out and changed the ignition right on the spot and so far everything is working ok. Does that switch have anything to do with the defrosters and fan going on?

uggh that sucks, well jwsmith did say that earlier in this post. I have to believe that it was the source of your problems. I said relay because, as a practice I try the easy, and more inexpensive stuff first. But I am glad that you got it worked out.

Thanks JW, To bad it did not sink in my hard scull, when you mentioned ignition. I learned the hard way.
Stompin60, Thanks for all the replies too.