The promises by your employer do not matter on this context, those are "gratuitous promises" thay they may frely go back on. However, IF there is a medical need for air conditioning for you not merely that you feel faint or nausous, but that there is medical evidence that as a diabetic, you need air conditioning to manage your condition or function, or that without it, you will suffer injury, then the employer may have to furnish it as a "reasonable accommodation," which is required under the law e.g. the Americans with Disabities Act.If there is such a medical need, pull together documentation of it e.g. a note from your doctor relevant medical literature and armed with this material, speak again with your employer and request a reasonable accommodation for your disability. If they still will not provide it, contact the federal EEOC or your state equal/civil rights agency to file a complaint