Heat Only Get Warm All of A Sudden

[spadepro22]

My heat is blowing, but its only getting warm. It used to blow very hot and I'd have to turn it of by the time I took a 20min drive with it on the 3rd knob. I've checked the fluid, its full. The t-stat is working, car doesn't pass the halfway point on the temp gage ever. No know or obvious leaks. The vents are all open in the car. If the heater core was bad, would it still even blow, and what else to check for?

 

[BurrowZ]

Have you tried a quick coolant flush, or even just a heater core flush? I would start there.

 

[Diamond Star Werks]

Heater core is just a small radiator with a fan. Only way for it to be "bad" is to be leaking or clogged. Poor coolant flow or low coolant level/temperature are the things that would make it blow colder. As well as the vent doors not opening/closing properly.

 

[spadepro22]

How do I flush the heater core?

 

[BurrowZ]

How do I flush the heater core?

Drain coolant, remove both hose ends that lead into the firewall, flush just the top hose and let the bottom drain out.

 

[spadepro22]

Drain coolant, remove both hose ends that lead into the firewall, flush just the top hose and let the bottom drain out.

The two hoses here are the two runnning to the t-stat housing from the firewall right?

 

[BurrowZ]

The two hoses here are the two runnning to the t-stat housing from the firewall right?

One to the thermostat housing, the other runs to the back of the big water pipe.

 

[spadepro22]

Ok, I went and took a look. The top one runs to the t-stat housing and the bottom one to a hard line that runs into the big pipe correct? I have a feeling that the core is clean, because the coolant is pretty new but I'll flush it in the a.m. anyway.

Other options if the core flushes clean?

 

[Diamond Star Werks]

Flushing it with just water isn't going to accomplish much. Anything that water will flush out would just be circulating through the system most likely. If you want to flush the system you need a chemical flush to remove any solid particles and such that would actually be limiting flow.

You can by such flush at the parts store. You have to remove all antifreeze from the system. Block and rad. Add the flush and fill with water. Drive it around like that for an hour. Let it cool down then start it back up and drive it or let it idle for 30 min.

Then remove all water+flush from system and flush system thoroughly. Then drain rad and fill with full strength coolant till it reaches full. Run it through a heat cycle at idle (till the fans come on) and fill & burp system till no air bubbles can be see coming out off coolant. Its ok to idle car with rad cap off to ensure no air is in the system.

 

[buhay6]

Flushing it with just water isn't going to accomplish much. Anything that water will flush out would just be circulating through the system most likely. If you want to flush the system you need a chemical flush to remove any solid particles and such that would actually be limiting flow.

You can by such flush at the parts store. You have to remove all antifreeze from the system. Block and rad. Add the flush and fill with water. Drive it around like that for an hour. Let it cool down then start it back up and drive it or let it idle for 30 min.

Then remove all water+flush from system and flush system thoroughly. Then drain rad and fill with full strength coolant till it reaches full. Run it through a heat cycle at idle (till the fans come on) and fill & burp system till no air bubbles can be see coming out off coolant. Its ok to idle car with rad cap off to ensure no air is in the system.

^^what he said...... garenteed if its clogged that should solve it, if it doesnt then start looking at the heater control cables and linkages into the heating system under the dash, something could be stuck/broken which would also cause a problem.

 

[007jimmy]

dont we have a one way valve on the blend door vacuum source that likes to go bad. i know when i forgot to hook the vacuum line up that goes through the firewall mine was doing similar. ive also noticed that after a good WOT pull my outside air/incabin air lever will be in the center position.. its become habit to automatically push it back to where it was.

i would put the bend door through a couple cycles while listening to it to make sure everything is moving right. you should be able to hear the doors opening and closing with each position.

 

[spadepro22]

Are there any sensor on the t-stat housing that could cause anything like this?

 

[Diamond Star Werks]

Are there any sensor on the t-stat housing that could cause anything like this?

No there isn't.

 

[spadepro22]

Everything was flushed and coolant was pretty much clean, but it did get warmer. Not as hot as before, but better. There is so air in system. Anything else to try?