Heater Not Working

**fbodyNATION** · 11-27-2011, 10:58 PM

So i am on my way to work tonight & my heat does not come on,at first i thought the car needed to warm up a little before the heat started working,but after 13 miles or so nothing happens,no heat at all i live approx.20 miles from my job so the heater should have kicked on by then,but nothing happened i always let my cars run until they reach normal operating temps before i pull off,but i didnt turn on the heater until i left home,i put a brand new radiator,new hoses,new thermostat,new antifreeze just last week so i dont see why the heat isnt working,i checked to see if the heater core was leaking but it seems to be intact what else can it be? The radiator and overflow bottle are both full with coolant so what else can cause the heat not to work? Its not my T/A with this problem its my 05 Grand Prix GTP Comp G, i know this is an LS1 site but i just need help

**smokestack** · 11-27-2011, 11:19 PM

Are you able to feel both heater hoses to check if they are both hot? Just had this issue on my truck. Had to flush the heater core. Worked fine after that. So if only one hose is hot. I would imagine thats it.

**fbodyNATION** · 11-27-2011, 11:31 PM

Originally Posted by smokestack

Are you able to feel both heater hoses to check if they are both hot? Just had this issue on my truck. Had to flush the heater core. Worked fine after that. So if only one hose is hot. I would imagine thats it.

Thanks for the input,but no i didnt check the heater core hoses,it was raining & too cold outside & i did not think to check that plus i did not have a lot of free time to thoroughly inspect everything,but i did check the coolant levels they were fine both in the radiator & overflow container,i will check the heater core hoses tommorow though & BTW if it is the heater core hose how do you flush it? I never flushed a heater core before

**fbodyNATION** · 11-27-2011, 11:42 PM

Things i changed concerning this car's cooling system:
2005 Pontiac Grand Prix Comp G GTP Supercharged

1.)New Radiator
2.)New Thermostat
3.)New Overflow Container
4.)New Hoses
5.)New Water Pump Bypass Hose
6.)New Clamps
7.)New Antifreeze/Coolant
Like i said both fans are working a/c & cooling fans,car is operating at normal temp,heater core isnt leaking,water pump is working fine & isnt leaking ,a/c works great i never thought to check the heater until it got cold

**smokestack** · 11-27-2011, 11:51 PM

You can just remove both hoses from the engine and spray water through the hoses to flush it. I replaced the same things. Flushed the radiator and block. Was a few days later i had no heat. When i flushed my heater core it was so pluged up i had to use air. Sludge with what looked like parts of a old thermostat was in there.

**matt evans** · 11-28-2011, 12:15 AM

the dex cool orange is horrible for clogging up heater cores. As smokestack said, take your lines loose and run water through them with a hose. Seen too many people take cars to shops for heater cores and get charged for replacing one and all they do is flush them.

**justinmc978** · 11-28-2011, 07:29 AM

dont mix that dexcool with normal antifreeze, I learned that lesson a while back..

**KMdef9** · 11-28-2011, 10:22 AM

I replaced a few parts on my cooling system on my Jeep and had a similar problem.

What happened, while changing parts, I dislodged build up and it clogged the heater core since It's made of smaller passages. One hose going into the heater core was hot, the other cold. I did a reverse flush, with hot water, collected the nasty water, poured concentrate antifreeze into the heater core (I did this a garage in freezing weather) and got the hot air back.

**Johny Bee O** · 11-13-2012, 11:48 AM

Hi all

I know this thread is old but i have the same issue. Did you solve them?

My Story:

Heater is weaker day after day until it blows only cold air. After that i replaced the orange dexcool with green glycol stuff. I removed the heater hoses and flush them with watertube.
After that the heater is working much better so 70% (100% melting the plastic

). Now 2 weeks later, same problem, heater blows cold air

. Heater core plugged? any suggetions?

regards

Johny

**blackcar** · 11-13-2012, 12:24 PM

When you went from orange to green did you flush the block or pull the drain plugs? If not you had quite a bit of orange still in there, and mixing orange with green is not good.

**Johny Bee O** · 11-13-2012, 12:44 PM

I disconnected both waterpump hoses and the drain plug at the radiator. Recently i saw orange mix in the radiator, i thought all water was out of the engine. But know i know there is another drain plug between the gap of the starter and engine block . Hmm thats sound to flush the complete system, i should use a cleaning liquid?

**Johny Bee O** · 11-15-2012, 10:16 AM

So problem is fixed. a flush solve the problem

**pajeff02** · 11-16-2012, 02:54 PM

When you flush a cooling system, it is always a good idea to push water through the heater core in reverse of its normal flow. Had a '98 Durango that was always plugging the heater core no matter how often I serviced the cooling system.

**2002ssslp** · 11-16-2012, 07:19 PM

Did you check your heater box to see if the vacuum door is operating correctly. If the door on the heater box does not open, NO HEAT !

**Johny Bee O** · 11-18-2012, 07:02 AM

My 01 Camaro has electric control not vaccum. Vaacuum is only the postion where the airs comes out (dash, legs)
Ah there was little problem, i fill the system with new fluid over the reservoir. I stop fillig after it comes out of the reservoir.
After that i start the engine and wait, but there was no addional fluild to add. After 5 Mins the cars run hotter, than before.
I remove the big hose wich goes to the upper side of the raditor and remove it. Okay i know i should not do this wen the cool system is hot.
But there was no time, so i relase the hose and puff much steam, but not much water comes out.
After that i refill over 3 quarts water in the system. After that the engine is run normal and heater is 100% function.