Heater not working properly

Welcome to 2CarPros. and welcome back:

This is an interesting issue because the when you increase the temp, the blend air door actuator is what should react. When you change direction of air flow, there is a different actuator which should respond, the mode door actuator. I think what we should start with is the mode door actuator. What I would like you to do is disconnect it and see if changing the temperature still has an affect on air flow direction. If it does, then we will need to inspect the mode door itself.

The mode actuator is located on the HVAC box under the dash. If you look at the attached picture, I highlighted both the mode door actuator and blend air door (air mix) actuator. You can see they are not close. That is what is causing me confusion.

Regardless, if we find air flow changes after the mode is disconnected, we will have to inspect the door and make sure nothing is loose or disconnected.

Let me know what you find.

Joe

Thanks for the information! Thankfully I have warranty with my dealer so they will be inspecting it, free of charge, on Saturday morning. I will let you know what they say.

Welcome back:

Happy to help. Let me know what you find. I'm interested in knowing what they find.

Have a good weekend,

Joe

Got the call from the dealer just 15 minutes ago, turns out all the actuators and doors are working as they should, it is the heater core that has some “calcium build-up” which is clogging it and preventing heat from flowing out. They want $570.00 for labor and parts since my warranty plan does not cover the service since it is not a part replacement. Can I do this myself because I don’t plan on spending that amount of money?

Here’s the invoice.

Welcome back:

I can't quite read the RO. Are they replacing the heater core or are they going to flush it? I would try flushing it first.

If it is a flush, you can do it. I attached two pictures below. The first one shows the heater hoses and how they connect to the core under the hood at the fire wall. The second pic is an exploded view of the heater core. I circled the core, and the steel hoses which come through the firewall into the engine compartment.

In pic 1, you will see the hoses disconnected. That it the what you have to do, disconnect the hoses. However, you will need to drain the cooling system partially to prevent coolant from leaking when you remove the hoses. You will still have some loss at the hoses, but it should be minimum.

Once coolant is drained in the radiator (about half way down), remove the hoses. At that point, take your garden hose and spray water through one of the two steel lines. Water will come out the other steel hose. Do this until the water is clear.

Next, reverse flush it. Basically, spray the water into the other tube until it is clean. If water comes out easily and is clean, you're done.

Reconnect the hoses and refill the coolant. Once the coolant is full, turn the heater on high and start the engine. Allow it to warm up. It should bleed the air from the system itself. If it doesn't, let me know.

Please let me know if you have questions or need help. Also, let me know if this takes care of the problem. One more thought, I find it a lot easier if I have a piece of heater hose long enough to push on to one of the steel heater core tubes so I can just spray the water into that. It's easier because first, you aren't trying to reach for the heater core tube with your garden hose, and second, it's rubber so it's easier to spray water into it.

If you decide to get the hose, get about a 3 foot section from any parts store. While at the parts store, see if they have any flush products specifically for heater cores. They will have radiator flush, but I question if that will work for this.

Take care and let me know how it goes.

Joe

They said it needs a flush, not a heater core replacement which is better for me! But thank you, I will definitely be trying this!

Welcome back:

I can't believe they were charging you that much for a flush. Wow! That is something which would be under $100.00 here. I just don't understand things anymore. I had a customer that was quoted $1,400.00 to replace an alternator in a Honda this past week by a well known national chain. I did it for $250.00. I guess one of two things. Either I'm just getting old or I need to raise my prices. LOL It must be age. I couldn't do that to someone.

Take care and feel free to let me know if you need help. Also, let me know if this helps take care of the problem.

Joe

Yeah I definitely knew it was a rip-off as soon as they told me the price through the phone. I will be doing it myself as I just located the two hoses going into the firewall and there is plenty of wiggle room to remove them so it should not be too hard, dealer prices in general are known to be ridiculous!

Let me know how it works out for you.

Take care,
Joe

Hey there,

Finally got around to attempt to fix this issue of mine. Bought some clear rubber hose from Lowe's, got some fresh coolant and got started. Man was it a pain in the ass to remove these two heater hoses after removing the clamps, I had to remove that long stabilizer bar on top of the engine in order to have more room for my arms and hands, along with more leverage. As soon as I started flushing the core with my garden hose, I noticed a faint amount of particles flowing out but mostly really light green coolant coming out. I sealed it all up, started the car with the heat on high, and drove around for a bit, I still have no heat.

What gives?

Wow, that looks really clean. And you have no heat? Were you able to bleed the air from the system? Do both heater core hoses get hot when the engine is warmed up and the heater is on high?

As clean as that is, the core most certainly isn't plugged.

Let me know.

Joe

I did not check the temperature of the hoses, I do have a temperature gun that I can use tomorrow to check that. But yeah, it certainly wasn’t clogged from the looks of it, that Honda dealer should really reconsider the “technicians” they hire, I do not know where they got that it was clogged. My guess is that it is a blend door issue, because whenever I turn the temperature all the way up to “hot”, the air starts blowing from the defrost and from under the dash. What do you think?

I agree. It is an actuator issue. Let me know what you find with the temperature.

Take care,
Joe

Where are the actuators in this particular vehicle?

Update.

I went ahead and messed around with the AC controls, as there are so many buttons on the dashboard, and I managed to change the settings in order for the air to blow out only from the front vents and not the defrost, all while I kicked the temperature all the way up to hot. However, I checked under the dash to look at the blend door actuator and everything is properly working, the lever moves up and down in correlation to the temperature change. The air on the passenger vents is barely warm, and the air on the driver vents is cold, what gives??

Did you try removing the blend door actuator to confirm that the door is moving?

No I have not. I would have to try to figure out how to get to it.

Hi,

If you remove the actuator you should be able to see if it moves.

Let me know if I can help.

Joe

So I checked both heater hoses going into the firewall with a temp gun. The top heater hose reads 135F, bottom hose reads 120F. Both hoses read over 160F from where they start, near the thermostat housing.

You should be feeling heat in the vehicle. However, I'm surprised the temp dropped that much. Are you getting any heat in the vehicle?

From the two passenger vents, only the small vent next to door is actually hot whenever I have the temperature all the way up. The passenger front vent is lukewarm, and the two driver side vents are cold, no heat whatsoever .

Something has come apart. If you have full air flow and control over the mode door, something isn't allowing the heat to enter. There is only one heater core. If you have heat on one and not the others, it's not a core issue. You have replaced the air temp actuator. I have one more suggestion. Try this self diagnostic test and see if any codes show up.

_______________________________

2008 Honda Accord V6-3.5L
Heating/Air Conditioning
Vehicle Heating and Air Conditioning Testing and Inspection Reading and Clearing Diagnostic Trouble Codes Heating/Air Conditioning
HEATING/AIR CONDITIONING
General Troubleshooting Information

How to Use the Self-diagnostic Function

The HVAC control unit has a self-diagnostic function for heating, ventilation, and air conditioning system. To run the self-diagnostic function, do the following:

1. Turn the ignition switch to LOCK (0) and then to ON (II).
2. Set the FAN CONTROL dial to OFF, the TEMPERATURE CONTROL dial on Max Cool, and select the VENT mode.
3. Turn the ignition switch to LOCK (0) and then to ON (II).
4. Press and hold the RECIRCULATION CONTROL button, then within 10 seconds press and release the REAR WINDOW DEFOGGER/MIRROR DEFOGGER button five times. Release the RECIRCULATION CONTROL button; the recirculation indicator blinks two times, then the self-diagnostic begins.

NOTE:
- The blower motor will run at various speeds when in the self-diagnostic mode.
- If there is any problem in the system after the self-diagnostic function is finished, the recirculation indicator blinks Diagnostic Trouble Code (DTC) 1 through 15. In the case of multiple problems, the recirculation indicator blinks in order with the lowest number DTC repeatedly.
- If no DTCs are found, the indicator does not blink.


pic 1

1 - 15

pic 2




Clear the DTCs

When the problem is repaired, DTCs will automatically clear.

Max Cool Position Function

When the mode control button is in the MAX A/C position, the HVAC control unit will automatically select the recirculation mode and turn the A/C on. If the recirculation switch is pressed when in MAX A/C, MAX A/C turns off. If A/C is pressed when in MAX A/C, the A/C turns off.
_____________________________________________

Let me know what you find
Joe

So I took my car to the dealer once again because the timing belt needed replacement and I told them that I had flushed the heater core myself and explained that it seemed like there was no clog at all. They checked the car again for the heater issue when they replaced the timing belt and they told me that everything looked good, the blend doors all worked, the vents were properly working and they’re more than sure that the heater is clogged. They told me that once it is flushed, one must run the car for 8-9 hours, not just drive it around for a bit like I did. How legit does this sound?

Once the engine reaches operating temp and there are no air locks, that should be all that's needed. I never heard of driving 8 to 9 hours to check the heater core or to make it operate.

If I recall, when you flushed it, the water flowed freely in both directions. If that is correct, that isn't any indication of a heater core issue. Are both heater core hoses getting hot now?

Let me know.
Joe

That is what I thought when he initially shared that information. Every other place I have looked at have said just to wait until the car to reach operating temperature, I am pretty sure it should not take that long.

I did not check the heater hose temperatures before doing the flush, but a couple of weeks ago I did check with a heat gun and they were around 130 degrees Fahrenheit.

Hi,

That's a little cooler than I would expect at operating temperature, but you should be getting heat. I have a feeling this is a blend door actuator issue.

I am assuming it is the passenger side blend door, I only checked the driver side one and it is functioning properly. The heater hoses should be checked while the heater is on, correct? I think I might have checked them with the AC on .

Hi,

Check the heater hoses with the engine at operating temp and the heater on.

Let me know.

Joe

So I went ahead and turned on my car, let it sit for about 15 minutes till it got to operating temperature, with the heater on high. Used my heat gun to check both hoses going into the firewall, top hose read 138 degrees, the bottom hose read 124 degrees.

I also went ahead and checked all the vents, the small drivers side vent near the door read 43 degrees, the front drivers vent read 51 degrees, front passengers vent read 68 degrees, and the small passengers side vent near the door read 92 degrees.

If you had 92 degrees at one point, something is going on in the HVAC box. I want to say mode actuator, but at this point, I would have to remove the assembly and check to see if something is broken, disconnected, not getting power and so on.

Take a look at the pic I attached. It shows both actuators that have been in question. One is the mode door actuator which directs air flow direction. The other is the air temp actuator. At this point, I hate to ask again, but is the manual HVAC or automatic?

If you had 93 degrees at one point, the heater core isn't plugged. You wouldn't be getting heat if it was. Interestingly, if you had them replace the heater core, they would have to remove the HVAC box.

Let me know if you have confirmed both of these actuators are working.

Joe

Yes, the vent that is blowing 93 degrees has always been hot, that is the small passengers side vent near the door, but it is the only vent that blows hot. I only checked the actuator under the steering wheel as I changed the temperature from hot to cold, it was moving and functioning properly. I have not checked the actuator on the passenger side because I do not know how to get to it from under the glovebox. I believe it is an automatic HVAC, what is the difference between manual and automatic?

Hi,

Automatic VS Manual is simple. With an automatic system, you pick a temp and the system maintains that temp. With a manual, the air temp coming into the vehicle is controlled by the driver via the blend air door.

I attached a pic showing both actuators.

Joe

I have this setup:

If I can tell, it looks like the one button indicates auto, which would be the automatic climate control.

You know, a thought just came into my mind. If I remember (and bear with me. It's 2:11am here) there was an issue with a sand like material in the engine block cooling system from when these were new. I wonder it that is blocking parts of the heater core and hasn't come out when you flushed it.

It's just a thought. I'm a bit tired at this point. LOL

Joe

Well like you said, if I am getting some heat then the heater core may not be plugged. I have yet to check the passenger side blend door simply because it seems to be covered and somewhat difficult to get to.

I totally understand. I can't tell you how many times it felt like I was standing on my head to access actuators. Not only are the hidden, but also there is usually hardly any room to work on them. I miss the old mechanical cables. They were much easier to deal with.