1999 Grand Prix GT Heater Prob.

Since we have had this cold snap in North Dakota (-30 for highs). I have noticed I cannot get the heater to get hot. Replaced thermostat, flushed system and replaced resistor due to #5 spot on the fan being out. Its blows warm air but not hot. Temp. gauge barely gets above 160 even after idling for 20 min. Where do I go from here? Someone please help, its getting expensive.

I am an automotive service manager and have recently finding many problem with heating and cooling systems on GM cars. After a little searching I have found the problem to be Dexcool! I bet you get, #1 brown clumps on your rad cap, # 2 rusty color anti freeze, #3 heater problems, #4 cooling problems in the summer when standing still, # 5 an erratic temp guage. If you have any of these, I had all of these! Being a service manager, I did flushes on vehicles, including my own, changed radiators, heater core, t-stats, etc. And it solved the problems temporarily, but the problem came back. I have a friend in GM( a service advisor) and deal with many dealers during the day, when this problem first became commonplace, between one to two years ago, I got the info from my friend that the problem was with the Dexcool. I flushed my system, replaced the clogged heater coreand filled with good old green antifreeze and my problem was solved. By the way, I changed the heater core before switching to green antifreeze and got the same result. Except this time, the heater core was easily blown out with a garden hose. I now recommend this to every vehicle that enters my shop. Think about this. Vehicle warranties average 5yr/ 60,000 miles. Dexcool is called 100,000 mile antifreeze. What better way to get your car in the dealer after the warranty is up then to have the Dexcool break down and screw up your heating and cooling? Don't believe me, ask any car owners that have taken my advice online. Believe me?