Turned on the heater the other night and I noticed the air flow coming out the vents is maybe 50% as strong with the temp set to 90F as it is when it's set to 60F. I tried with the air going to the footwell, and it's the same thing. With winter around the corner, I'd like to get this fixed beforehand if possible. Any suggestions on the issue? I'm thinking maybe the fins in the heater core could be partially blocked? If so, this would require it to be removed which is a very tedious job I hear.

 

You know, it could be because cooler air is more dense, and warmer air is less.

 

No the difference in vent flow is much more drastic than air densities would account for.

 

Check your codes, more than likely the actuator switch is burned out, shorted, bad ground, etc.

 

No codes. I think it's a physical obstruction in the heater core ducting. If I listen closely to the passenger footwell, I can sort of hear what sounds like a flapping/slapping noise when the heat is on. The heat gets as hot as normal, it just blows maybe half as strongly compared to the cool/AC air. Is there any way to access the heater core without removing the entire dash? All I assume it's some leaves or something, all I need to do is reach my hand in, not change it out. Everything I search for regarding heater core is to R/R, which requires complete disassmebly of the interior it sounds like, way too much work for some heat. Plus with Texas winters, I really don't need it working at 100%, but it annoys me that it doesn't.

Edit - blower fan is free of any debris. I know I can feel the AC evap when I remove the blower fan with the HVAC on AC mode, if I switch it to heat mode, then cut the power, will the blend door stay open so I can reach into the heater core housing?

 

update - it's definitely debris around the heater core. I removed my blower fan and stuck my hand as far into the ac evaporator and got a bunch of dirt and leaves out. Couldn't reach the heater core though, and I'm not sure there's anyway to access it without removing the entire HVAC unit? Can anybody confirm this? I don't need to remove the core, just clear the duct area out.

 

Not sure on the answer to your question, but that is the area that mice love to set up for the winter.

 

Doubt i have any mice. No smell, plus i daily the car so it never sits for too long. I'll probably tackle this at some point. I'll replace my cracked HUD bezel at the same time.

 

bump.

anyone who has replaced their evap or heater core care to comment? How/where does the heater core sit in relation to the evaporator coil? And is there like a door or something that will blend the air? It doesn't look like there's anyway to clean it out short of removing the HVAC assembly and taking it apart, which of course means ripping out the dash, not to mention evacuating the freon and etc. For reference, the heat with the max fan setting blows about as much air as with cool at the 2nd fan setting. I use to occasionally park near some trees and I'd always get leaves and pine needles and etc falling on the car. I'm guessing some made it under the rubber mesh that sits on the cowl.

edit - looking at pictures of the HVAC assembly http://forums.corvetteforum.com/1581487172-post4.html and http://forums.corvetteforum.com/1560382509-post4.html , it looks like the evaporator sits in front of the heater core. So I don't really see how I could have an physical obstruction from debris on just the heater core. I'm a little lost on why the air is so weak on heat now. It doesn't look like there's any blend door of the sort that diverts air to/from the heater core or AC evap, so I'm assuming it just varies the amount of coolant that runs through the heater core in order to change the air temp? I'm also not sure what's wrong with my heater now. It blows cold and strong with the AC on, and hot with the heat on, just not strong.

 

To give you an idea on how complex the AIR BOX removal can be, here is how they build the C5

They put the HVAC Air box on the assembly line and then they bring ALL the other parts out and build the car around it.

YEP,,,,,,,,,,,, Its a BIG job.

BC

 

NO!!!! My heater whispers on me even at full strength

 

Yep I changed out my heater core a couple of years ago, it was loads of fun.
More than likely you have an air blend problem or a mouse nest sadly there is no other way to access that area without removing everything.