There are modules called "Regeneration & Cooldown Module" which ONLY give heat reduction and energy regeneration.
Actually from a certain level on these modules are most of the time prefereble to pure heat or energy modules because cooldown and energy regeneration is much more important that just eh amount of energy and heat you got.
With regeneration you can "tank" more energy of heat and therefore let you last longer.
I alreadyhad many mechs which had 40 heat points and 50 cooldown meanding when somebody overheats me to 50 heat points I still get back to 0 heat with a single shutdown.
Checks all the available moduels guys and think about what they mean