This doesn t sound like heat intolerance. It sounds more like you are having a problem with your lungs or heart. Are you having problems with fevers? I m not sure what you mean by a broken body radiator. You need to be examined by a doctor and have some bloodwork done. Check for an overactive thyroid. This could cause a hyper metabolism which might make you feel heat intolerant and the constant stress on your body could eventually result in fatigue and problems with your heart. I m particularly concerned about the breathing difficulties you have with walking and carrying heavy things. What is the problem sitting up? Do you get dizzy, heart pounding, or short of breath? I strongly suggest you see your doctor and get this diagnosed so the correct treatment can be started. Hope this answers your query. If you have further questions I would be happy to answer them.