Cat 930H is getting hardly no heat from the heater, could it be a thermostat problem and where is it?
Post your machines serial number and maybe a nice person will send you a schematic, and heater valve location. Have you pulled the actual rad cap off to check fluid level, not just the overflow container. Just asking. Are your cab air filters clean, 2 of them I believe. Does the fan turn strong. Check these things first. Simon C