Q: I have a 1999 chevrolet silverado 1500 5.3 vortec, engine is running hot very quickly and heater is not blowing hot.

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My truck runs hot rapidly after i start it. I tried to turn the heater on to let the heat out and it blows cold. Also the truck will run hot while parked with the ac on. I just had the truck serviced at a penzoil quality lube. There are no visible leaks from any hoses, coolant reservoir, or passenger flooarboard.

My car has 275000 miles.
My car has an automatic transmission.

Hi there. Generally speaking, when the heater is blowing cool air and the engine overheats, it’s caused by the same thing - a clogged or damaged heater core. The coolant from the motor once hot circulates through the heater core to supply hot air. If the core is clogged with excessive debris or sludge, this will cause an overheating issue and the heater problem. You might want to have a professional mechanic complete an overheating inspection to correctly identify this problem and recommend the right repairs.

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