Burning out door actuators

Hey guys, I got a question for ya...

I installed an alarm in my car back in Feb./05...My car never had power locks, but I installed door actuators into each door, and wired them up with two relays. About three months after that(they worked fine by the way), I was wiring in a varad scanner, and I thought I shorted them out, and burnt both out.

Well that was fine, I got another set, and they worked, problem solved...Well just the other day, my newer set of actuators stopped working..I just ripped the door panels apart again, and both actuators were burnt out again...

My question is- Why do they keep burning out after approx. three months of use?

I checked the relays, and both seem to be functioning properly, but I'm not getting any power to the actuators...?I was thinking maybe a bad ground? or one of the wires that go from the relay to the actuator being bad and shorting or something?

Also, not sure how revelent it is, but I had to wire my alarm scanner up using three relays, because my alarm doesn't have a "ground when armed" wire. Basically the scanner is turned on by taping into the unlock and lock wires from the alarm modual(same ones that go to my actuator relays), and the three relays function together turning ther scanner on and off...The scanner has worked perfect since I installed it, and still works how it should. So could this be contributing to my problem?

I really appriciate any help given, and since my baby is going away for winter in a week or so, I really want this problem solved soon...Thanks

Deppends on the quality of the product.....don't use "the cheapest one you can find" I personally use SPAL products.

If you think about what this thing has to do.....thats alot of work....specially for a 5 dollar piece of junk. If the unit your using (the alarm) has programable adjustable lock pulses, make sure it set for the shortest poss.

http://www.spal-usa.com/

I have my alarm set for a shorter pulse(0.8sec.)...not sure what the actuators are generally rated at. The actuators failed, but I don't think the relays have yet, cause both(relays) are clicking when they should be. Hopefully I can go over every wire to and from the relays tomorrow and see where the problem lies. The relays all have fuses, and all are still good as far as I could see.

The actuators are just cheaper ones, but my idea was get them working right before I buy a good set, so I don't burn out even more moneys worth...lol

I was thinking also, that they do seem  to "stay on" longer then really would be required...Like it would go "unlock, quick pause of still pushing, then power released" if you know what I mean.