Why is the heater in my 00 pontiac grand prix gt blowing out cold air?

Does your temperature gauge show the engine is warm if not and it has been running for like 1o minutes probably have to replace the thermostat. If it is showing warn then probably the heater core is plugged. It could also be the the valve that allows warm water into the core is not working.

Pontiac Grand Prix Heater Problems

1) no coolant 2) bad heater core 3) on pontiacs they have a gay *** hose that connects the heater core to a few things that splits off and they want a arm and a leg for it dealer only (but you would notice water on the floor sometimes due to hose leaking

Contrary to what everyone is telling you it is probably not a coolant problem, If you are low on coolant or if the thermostat is stuck closed, YOUR CAR WOULD BE OVER HEATING!

Some of the Grand Prix GT's have a digital dual zone electronic climate control system, I.E. you can set the driver's area at one temp and the passengers at another temp within 6 degrees, the cars computer controls the temp.

If you have this it may be a problem with the computer, more likely it is the electronic control for the valve that opens and closes to allow coolant into the heater core, if it has burned out or become unplugged no signal is being sent to tell the valve to open. Also if you have been into the dash, worked on the radio or something else, the actual temp control could have gotten unplugged.

I had a Grand Prix GT with the climate control, never had this problem though.

However I had the same problem with my SVT Contour, would turn the dial for warmer air and nothing, turn out to be the electronic control was burned out, replaced it a couple of years ago and is still working great.

It may be either your Heater Core, your Thermostat, water pump, or lack of antifreeze in the radiator/coolant tank. I just recently had this issue with my 88 Firebird, and went almost 2 weeks in Chicago winter weather without heat. However, we found out that I had a massive water pump leak and it was just spilling antifreeze so none could even get into the radiator.

We got that fixed and i've been fine since then.

Okay, I'm going to be serious and not sarcastic like everyone else. There are 2 things that would cause this. 1: a bad heater core (Unlikely) or 2: no coolant. You most likely have low coolant. Your car "steals" heat from the hot coolant and uses it to heat the interior. if there is no coolant, there is no heat. check your radiator when its cold, and add if necessary. Common problems on your car are leaking lower intake manifold gaskets, and bad upper intake plenums. The "coolant elbows" (90 degree black piece of plastic that go into the block) below the alternator are notorious for cracking. have the car running when you look for a leak from the coolant elbow.

There are 2 possible answers 1 the car has not heated up fully if u did that then u might have a broke heater core

Look for water leaking ,the hose could be burst or the pumps burnt out

your air conditioning is on.