There's a couple of reasons this could be happening. In your interests, its best that next time you post the porblem with specific details and a bit of history.
Its a 2003 Mehran and unless you've had the wiring significantly tampered, there should'nt be need for a relay. I have a 2003 Nov Mehran CNG, and its never displayed such problems.
Firstly open up the radiator cap in the morning or when the when the car is COLD. See if the thermostat is working, meaning does it open water flow. Should be visible as moving water in the radiator accompanied by the thermofan. If the water starts to flow, but the fan doesn't turn on, have wiring checked before throwing on a relay. Check Polarity, i.e. see if the fan is "sucking air" (front-back) not pushing it (back-front). Check water pump belt for tension and if you're adding water instead of coolant, flush your radiator and check for flow. Also check A/C heat exhanger for blockage. The fins usually get bent while highway driving and there's usually alot of bugs that get stuck.
The front grille has a metallic air restrcitor covering part of the grille from the inside. Make sure your vehicle's not been removed or isn't loose.