Amp cooling fans going crazy

[djm]

I built an amp rack for my car subwoofer amp, and there are two fans at the bottom (of different size, one pulls more amperage than the other) and they are wired in parallel to a relay which also turns on the amp. (when the amp goes on so do the fans) well the positive and negative for the relay are wired into the amp's positive and negative terminals. i tested it out in my workshop with a ac/dc transformer and everything worked fine, both fans turn on, the bigger fan pushes a little less air and the smaller fan (of better quality) pushes more air (normal) so everything checks out and i go put it in my car, well i turn the car on and the amp turns on...the smaller fan dosent turn on, the bigger fan is going at about 3 times its normal speed (and im talking SELF DESTRUCT type FAST) so i turn it all off and bring it back inside try it again and it works perfectly, so i put it back in the car and it works fine, the next day it freaks out again and has the same problem. i can also hear the fans noise thru the subwoofers.

i dont know why this is please help out.

Thanks,

John

[skittlesRgood]

pull out the DMM and see if you find any weird voltages. probably wired something wrong.

[djm]

it was a thermo resistor that was hot because it was like 90 degrees outside and thats what caused it to happen only outside