Please help! Heat doesnt work!

[em5568]

I double checked the actuator, i can visibly see the range of motion. It currently moves between the two lines indicated in red. I had installed a new actuator when my heat began giving me issues.

 

[east302]

That range mimics the one that you'd see for the mode actuator by the gas pedal, so that looks correct.

Can you see the air door with the bottom cover off of the core?

 

[em5568]

Yes, i didnt realize i was capable of seeing the actual door being positioned from where i was. It was a tight squeeze but attached are a couple pictures from full cold, no blower on and full hot no blower on. You can physically see it move open and closed. so it seems to be functioning properly. Which now leads me back to thinking it may be a potential flow issue.

And thanks again for all your time and patience east. I appreciate all the help man
-E

 

[em5568]

Would you happen to know if using a radiator pressure tester would properly burp the coolant system? i believe they rent them at autozone.

 

[east302]

I agree, if the damper is closing and the water valve is opening, then it has to be a coolant flow issue.

Are your hoses installed correctly...not reversed? Inlet comes from the goofy intake connection, outlet goes to water pump. The hoses on the firewall side of the valve cross each other.

 

[east302]

Here's mine, 1998 350.

Top hose going to water valve is from the intake. Lower hose is to water pump.

 

[em5568]

East, you are a gentleman. I will double check that tomorrow when its light out and touch base with the orientation, though i have checked my lines per-diagram a few times and everything lines up. You never know, will touch base tomorrow!

Thanks
-E!

 

[em5568]

Alright, so i have triple checked the hoses. They are all right as per your pictures and the GM diagram i have, I'm almost starting to wonder if there is potential for there to be a factory defect in the new heater core i installed.

 

[em5568]

Also, a couple other small things i'd like to add (In case it makes any difference, maybe it'll give someone a light bulb).. At one point, i did have heat. But only while driving, it worked fine. Then out of nowhere that stopped as well. I can also still feel air coming into the car even with all the hvac controls off. As if something is stuck open.

 

[Big Mama]

Great advice so far. Did you replace the heater core for a reason or was it because you thought it was the problem? My guess is vacuum at control valve. I had an old Mercedes that would blow hot if I idled but when driving. I went through all the steps you did and found a bad control valve and a small vacuum leak. When you test everything make sure the dash dial is set to hot and the fan is on all the way. Keep at it. You’ll get it fixed.

 

[shoplizard]

Hi, I have read your story and I feel your problem is a flow through the heater core problem. When you replaced the heater core, what was the condition of the coolant? Was it clear and not cloudy and orange, like rust sludge. I used to see a lot of that in R and W engines. Did you flush the cooling system thoroughly, pulling the drain plugs to flush the block? If the coolant was contaminated with the rusty debris when you replaced the heater core, it could plug again shortly after replacing it. This will cause a restricted coolant flow through the core. You note that the core will be hot with no air flow but with the fan on and low air temps, the limited coolant flow will cool rapidly and produce cool air again. I suggest you back flush the heater core and if the coolant is contaminated flush it thoroughly and replace with new 50/50 mix coolant.

 

[retiredsparky]

^^^^^^^^Bingo! Very common in older vehicles that at one time or another did not have properly scheduled coolant replacement, especially with the "long life" coolant. A gel can build up in the coolant system, or rust or silicates, etc.