Blend door on chevy suburban

[AaronW]

hey everyone. I've got a 1995 Suburban 2500, 454 engine.

My heater doesn't work. It's got a new thermostat, both hoses going to the heater core are warm when engine is warm, and I've flushed the heck out of the front heater core. Back heater doesn't seem to work either.

I've seen some youtube videos on the actuator for the blend door, but it seems to me like I ought to see first if maybe the blend door might be stuck. Maybe that isn't it at all, but I'm just trying to envision possibilities.

Where is the blend door, so I can check that? Anyone have any other potential suggestions for what my problem might be?

Aaron

 

[bucket]

I don't remember why, but I changed the blend door actuator on my '90. Iirc, it is accessed by removing the glove box (my dash is the older style though) and it is on the top side of the hvac box.

Also, apparently the '95 hvac controller is failure prone these days. It looks like the '96-later unit, but it is not the same on the backside. Shaggy has another site called gmt400.com and it's a great place for info on the '88-'98 trucks.

 

[AaronW]

I don't remember why, but I changed the blend door actuator on my '90. Iirc, it is accessed by removing the glove box (my dash is the older style though) and it is on the top side of the hvac box.

Also, apparently the '95 hvac controller is failure prone these days. It looks like the '96-later unit, but it is not the same on the backside. Shaggy has another site called gmt400.com and it's a great place for info on the '88-'98 trucks.

Thanks for the site suggestion, I'll look at that. It's going to be 20 below zero tomorrow night, and right now, it's blowing sideways, snowing, and running about 5 degrees plus wind chill. Would be kinda nice to have a heater.

Aaron

 

[Catbox]

We have a 1995 Suburban as well.
I think there are 3 blend door actuators in them.
I had my kid change them all out at the same time as they can be buried deep in there.

Also check to see if there is blockage on the AC coil.
I quit using a mechanic because he said the AC worked fine.
He tested it in the shade and the temp right at the vent was good.
But there was no air flow a few inches away from the vent.

Kid cleaned that out like I had asked the mechanic and now it blows good and hard again.

 

[fast 99]

Just because both hoses are hot doesn't mean the core isn't restricted. You will need an infrared temp gun. Engine up to temp, blower and heater on high, temperature split between inlet and outlet should be close. If near or more than a 20-degree split core is restricted. Take the temp at same spot on each hose near firewall.

Of course assume full system properly bleed.

 

[bucket]

Just because both hoses are hot doesn't mean the core isn't restricted. You will need an infrared temp gun. Engine up to temp, blower and heater on high, temperature split between inlet and outlet should be close. If near or more than a 20-degree split core is restricted. Take the temp at same spot on each hose near firewall.

Of course assume full system properly bleed.

But 99.999% of the time, if both heater hoses are hot at the firewall, the heater core will be hot as well. So if both hoses are hot and there's cold air blowing out of the vents, there's an issue in the dash bits.

 

[fast 99]

But 99.999% of the time, if both heater hoses are hot at the firewall, the heater core will be hot as well. So if both hoses are hot and there's cold air blowing out of the vents, there's an issue in the dash bits.

If ice cold maybe, slight heat better check flow. It's very hard to positively diagnose a temp spread by touch. Even on severely restricted cores outlet temps are usually only 30 degrees lower. Cores flow a lot of coolant. Ever accidentally start a car with a heater hose off?

I am not suggesting this particular vehicle has a bad core it may very well have door problems. Only suggesting an additional diagnostic option before digging into it.

We have to be sure before recommending repairs. On today's cars it might cost $1000+ to fix a heater problem. Have checked customer vehicles this way for 15 years...... since I got a temp gun, it works.

 

[bucket]

If ice cold maybe, slight heat better check flow. It's very hard to positively diagnose a temp spread by touch. Even on severely restricted cores outlet temps are usually only 30 degrees lower. Cores flow a lot of coolant. Ever accidentally start a car with a heater hose off?

I am not suggesting this particular vehicle has a bad core it may very well have door problems. Only suggesting an additional diagnostic option before digging into it.

We have to be sure before recommending repairs. On today's cars it might cost $1000+ to fix a heater problem. Have checked customer vehicles this way for 15 years...... since I got a temp gun, it works.

Just going off of past experiences with the specific vehicle in question. The actual temperature of the hoses doesn't matter too much... if both feel warm or hot, there should be a similar temperature blowing out of the dash. If it's blowing significantly colder air, there is a problem with the temp blend door operation.

That is not to say that there isn't blockage as well and the temps may not be what they are supposed too. But that is a separate problem to diagnose, if needed.

 

[fast 99]

That is not to say that there isn't blockage as well and the temps may not be what they are supposed too. But that is a separate problem to diagnose, if needed.

That's true it just saves time doing the job twice. I got in the habit of checking the core temps on just about every vehicle in for a heating complaint. It's just too easy not to do it.

Temp guns today are a cheap useful tool.

 

[AaronW]

hey everybody, I'm finally getting to this problem, have some space cleared out in the shop. Had to get the flatbed for my 89 V3500 out of the way first. Ok, so is there a way I can check to see if the blend door is operating, without actually removing it, or do I have to pull it out in order to check that?

Aaron

 

[75gmck25]

I have not worked on a Chevy, but on the 2000 Ford Expediton it was fairly common to cut out a section of the plastic plenum to expose the blend door, and then repair or adjust. Then just patch and glue the plenum. In my case I also had a leaking heater core, so it all had to come out to be fixed.

On the Ford it was at least an 8 hour job because the dash had to be removed to expose the heater core. I hope Chevy had a better design.

 

[rusted nuts]

I had a square sit a while in the fall one time,, Damn mice got in the heater box and built a nest that covered the heater core 100%,, But Ya could smell mice piss 100 foot away

 

[AaronW]

hey guys, new question on this rig. I was replacing my driver's door pins, and broke both of those little retaining clips, prying them off the ends of the door pins. Anybody know what those things are called? I can't find any, and it's probably jsut because I don't know what words to type in.

On the other issues I started with, on this thread: So I think my blend door is ok. I got my fingers in there, and could feel the actuator turning when I switched the knob on the dash back and forth. So, I bought a gun, and blew out the coolnat system really good, and went ahead and replaced the front heater core. Fingers crossed. I got hot air out of it, though it did take a long tmie to warm up. 454's....

No heat out of the back, so I assume I'm gonna need to replace the back heater core, too.

Let me know, if you know what those little clips/push nuts, whatever they're called, are.

Aaron

 

[bucket]

New door pin and bushing kits generally come with new retainers. The original type round ones would be called starlock washers, push on lock washers, etc. The rectangular ones that often come with aftermarket pins probably have an assortment of other names.

 

[bucket]

Dorman Products - 13441

Push Nut Assortment - 2 each 1/8,3/16,1/4,3/8,1/2 In.

www.dormanproducts.com