Chevrolet Repair: Heater Problem, hose connections, waterpump

Question
I live in Oregon. I have an 04 K1500 Suburban w/24,000 miles. All service has been done on schedule w/dealer.After a day of skiing I restarted the truck. The truck had been sitting for 7 hrs @ 22 degrees. I drove a few miles when I noticed that the heat system was blowing cold air. The engine temp gauge read 230. I pulled over and checked the surpantine belt and the hose connections. They all appeared fine. I drove the truck home a distance of 130 miles. Even though the outside temp was 40 @ home the heater never came around to regular operation. The reading on engine temp would drop for a few seconds periodically to about 215 and warm air would come out of heater. Then would just as quicky turn to cold and the engine temp would go back up to 230. I called onstar and they ran a diagnostic and said as far as they could tell the truck was running fine. What do you think?  

Answer
Hi Matt, sounds to me like your coolant is low and you have a leak in the cooling system. The most common thing to leak is the waterpump. Take it in for repair, but check the coolant jug first to make sure it has coolant in it!!

Have a Great Day      Mark