varad hyper led's

I recently purchased 5 blue varad led's.  I am planning on putting them in the a/c vents in a 99 chevy silverado.  I plan to have them flash with the alarm led (which i will replace with a blue led), and the one's in the vents stay on when the parking lights are on.  I have a couple of questions about this setup.  Let me explain how I was going to do this and see if it makes sense.  I was going to cut the wires for the alarm led and use them to power a relay to control all 5 led's.  The positive wires of the 4 that are in the ac vents will also be run to pin 87a on another relay.  I will then wire the 4 leds to pin 30 of this relay.  I was going to use the parking light wire to trigger the second relay and send 12v to these 4 leds.  Does it seem like this will work without any problems.  One more thing.  Will hot and cold air cause problems for these leds in the future?  I think that's it.  Thanks

Let me clarify in case this is confusing.  All 5 leds will flash for the alarm.  When the parking lights are on the 4 in the a/c vents will stay on and the 1 that replaced the alarm led will still flash for the alarm.