I have a 2004 LS with 55,000 milesOnce the car warms up the only way I get heat
is when I start driving down the road. I get no heat while siting stoped and no heat
when 1st started siting still. I checked the over flow level and it seems to be at the correct
line when cold. I have no idea what the problem is my 1st thought was thermostat
I was just getting ready to trade it in a 06 or 07 but there's no way I canhide the
heat issue when whoever I trade it into tests drives it so I just will have to spend the $$
and hope its not too much !

 

Considering where you live it would be pretty tough at this time of year to hide it unless we get a freak heat wave but I don't see that coming.

I don't have much experiance with the heater at all. My first instinct is that there is an air bubble in the system, but then I don't think it should matter whether you are stopped or driving; the waterpump should take care of that.

I guess I would start to see if you can bleed the system though and start from there. The heating system can't be that darn complicated. It's only 2 radiator hoses to the inside of the cabin to another radiator with a fan on it.

 

I would say since you have heat when you are moving Tstat would be the first, second I check your blower doors and vacuum going to them and even vacuum leaks in the engine compartment. Third would be air in your cooling system but sounds like you have heat sometimes so this is a long shot .
Tstat would be my guess if it is already cold where you are!

 

I would check the thermostat first. Go ahead and replace it to eliminatepotential trouble with an inexpensive part.

 

First off,
What is the temp gauge in the car saying, If its in the normal range.
I would look at the heater control valve.
If its lower in the range then normal, change the thermostat. It most likely stuck in the open postion

 

1) if the temp guage is reaching the normal range, then it is not the stat

2) start the engine, and as it warms up, compare ( by carefully holding ) the heater hoses that go from the engine to the firewaal (heater) and back

3) if one is substantially hotter than the other, then the heater core might need flushing

4) check your cabin air filter, as with 50K, it may be plugged and the blower is working but not pushing any air thru. You can also check this by using the recirc mode, which closes off outside air, and permits the warm air to get warmer as it recircs thru the heater unit

good luck ..maddog