Volvo Repair: 91 volvo 240 inst. panel lights, fuse block, fuse box

Question
QUESTION: I have 1991 240 that keeps blowing the 8a fuse in the fuse block that is responsible for the instrument panel lights.  The fuse blows as soon as I turn on the headlights.  I'm not real knowledgeable about wiring.  I did connect a test light to the fuse block terminals and the test light lights when I turn on the headlights.  All other lights function normally other than what is on this circuit.  Any help would be greatly appreciated.  
Thank you.
Joe

ANSWER: Try turning off the dash lights by turning the dimmer all the way to the left. The rheostat may have shorted internally.

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QUESTION: Thank you for your response and suggestion. I turned the dimmer all the way left but the fuse blew again as soon as I turned on the headlights.  Anything else I can try?
Thank you.

Answer
The headlight relay is located on the driver's side under the hood. It has a metal cover and is held in place by two screws(located toward the front)Try unplugging the two electrical connectors and see if the fuse still blows.If it doesn't blow plug the connector in from the fuse box and see if it blows, if it still hasn't blown plug in the other connector.If it still blows with that disconnected the problem is inside the car, possibly a bad switch or shorted wire.