Chevrolet Repair: 1998 Chevy Blazer Heating Issues, intake manifold gasket, chevy blazer

Question
Hello, I thank you for your help in advance.  I have a 1998 Chevy Blazer 4x4, and this morning I noticed that all vents were blowing cold air (everything worked fine yesterday).  All vents were working at all speeds, and in all positions, but were blowing cold air.  I turned all heater/ac functions to off, waited 5 minutes, and then turned heater back on and got warm (not as warm as usual) temperatures for about 2 minutes, and then it went back to cold and stayed cold until I shut it off and turned back on 5 minutes later (in which it was warm, and them back to cold again).  My fiance' and I are aware of the Dexcool issues, and susequently have been flushing ect. every 30,000 miles. He beleives it to be simply a thermostat?  Can you please tell us if that is an accurate assumption, where the thermostat is located, and what are the other possible issues we may have if any?
Thanks Again

Answer
Hi Danielle, This sounds to me like your coolant is low and you have a small leak somewhere. I would check the coolant level in the radiator and if it is low as I think it is you need to locate the leak. Common area for leaks are....INTAKE MANIFOLD GASKET and WATERPUMP. Most of the ime it is the intake gasket. This will leak at times so slow that you will not see anything on the ground. GM has just come out with a new style gasket which is made of metal and rubber, instead of PLASTIC. I think this gasket will last much better! Let Know what you find.

Have a Great Holiday       Mark