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Madiganistan/Chicago
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Discussion Starter #1
2008 Accord 2.4 Auto EXL Dual Zone Climate Control 105k miles on car.

Blower works great on both sides
Mode control works great on both sides.
Tested with car fully warmed up.
BUT there is only heat on the passenger side. Drivers side is cold no matter if heat is directed towards feet, defroster, or top vents.

I have drained and filled coolant with genuine Honda Type 2 Blue coolant every 2 years since I purchased it.

After noticing this issue I just drained and filled the coolant again this afternoon.
Coolant coming out looked exactly the same as the new stuff going in. No change.

I took a flashlight and looked closely at the air mix/blend door actuator when I changed the temp with my other hand. They seem to both be functioning normally.

What are the chances that the heater core is clogged given my coolant drain and fills at 45k, 90k and now 105k?

Given the recent CRV TSB 14-063 for no heat on driver side vents see
2012 Honda CRV LX heater core - Page 2

Either I have the same clogged heater core problem as the CRV's...
OR
even though I can see the airmix/blend door actuator moving on the outside.... it isnt actually moving anything inside?? Anyone ever seen this problem?

Any other suggestions?
Thanks in advance.

Edit I just took off the actuator and moved the door control arm by hand, it is closing completely and when done quickly it makes that "thump" sound like when quickly changing controls from hot to cold or vice versa on an older cable operated setup...
 

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Thats interesting about the clogged heater core causing a similar problem. Would not have thought that would cause a one sided issue.
Did you have the heat on when you moved the door control arm by hand? If so, did it change the drivers side heat at all?
 

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Madiganistan/Chicago
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129 Posts
Discussion Starter #3
Thats interesting about the clogged heater core causing a similar problem. Would not have thought that would cause a one sided issue.
Did you have the heat on when you moved the door control arm by hand? If so, did it change the drivers side heat at all?
Yes and it didnt seem to change, when the actuator motor is connected the blend door arm makes the full and complete travel as well.
 

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Yes and it didnt seem to change, when the actuator motor is connected the blend door arm makes the full and complete travel as well.
What about the drivers side temp sensor? In the dash, down by your right knee if I remember correctly. If that has gone south, and is calling for no heat, no matter what the thermostat is set to, could that explain your issue? Not sure. With 105k on the odo, you could be experiencing the same problem as the CRVs. You're eventually going to have to take it in to see if they can track the problem down. Suggest the CRV solution if they seem too quick to jump at replacing the core. Let us know how this turns out. You may be acting as the canary in the coal mine for the rest of us on this. Good luck.
 

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Madiganistan/Chicago
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Discussion Starter #5
so the system uses this temp sensor regardless of which setting is used?
AUTO for sure
but even if i set the fan to HI and temp to HI?
 

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Madiganistan/Chicago
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Discussion Starter #6
Fixed!

I'll begin the post by saying ... I FIXED IT!

I used the method described in the CRV TSB that i noted in the original post.
Here is a run down
Supplies used
one 1/2 HP Utilitech transfer pump from Lowes $110
3 10ft sections of 5/8in I.D. clear vinyl tubing, 49 cents per foot, $15
2 brass hose connections 5/8 to 3/4 garden hose to go on either side of the pump. $10
1 new 5 gal bucket $2
4 total 7/8in O.D hose clamps from the connection to pump and to heater core, $3
2 28oz bottles of CLR $10

This is the picture from the TSB, My setup looked the same as this but I didn't have the filter part.


Pump and bucket setup.


connections at heater core, I started with the connections circulating as the engine would do for about and hour and then later switched it and did reverse flush for about 45 mins.


While running CLR mixture


While running CLR mixture. Turned into a cream like color and consistency.


after an hour, mixture foamed up and almost filled the bucket.


close up, not sure what this stuff was on the foam, obviously dark but didn't feel oily

I didn't take a pic but at the bottom of the bucket there was about a 1/2 teaspoon of grit collected. dark black particles similar to sand in size. I didn't have a filter and when I stopped the pump I could see a few small particle suspended in the water while flushing, So i think more stuff was dislodged then I could feel because much of it was suspended in the solution.

after this I flushed with straight water, about 10 buckets full

here is a quick video while flushing with water
https://www.youtube.com/watch?v=BZg-KAzHF4o

blew the heater core out with air and refilled with coolant.

Heat works equally on both sides now...!
 

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I'll begin the post by saying ... I FIXED IT! Heat works equally on both sides now...!
:notworthy:notworthy Major props to you for doing this yourself, and thanks much for the detailed DIY! Will be bookmarking this for future reference and hoping I'll never need it.
 

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Yeah, very nice of you to post the fix not only here but at bob's as well. Good work!!!
 

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Had Same Problem

Had the same problem with my 08 Accord (75,000 miles) - very little heat on drivers side.
Just flushed heater core as you described and the heat now works well.
CLR solution started foaming as soon as I began pumping but the foaming soon stopped.
I used the Harbor Freight pump #65836 which cost around $60.00 and it worked great.
Thanks for the write up!!!
 

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Cruzing Through Life!
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My heater just started doing the same thing.

Going to give this a try. Thanks!

:)
Looking forward to your follow up posts.

Will you add pictures to this website and not a third party site?
If you post the pics here, they will stay forever.
 

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Problem solved?

So I took my car to a local rad shop to have the heat core flush done instead of buying all the stuff...

Long story short:

45 mins heat core flush (they ran air through it)...
a lovely chat with the owner about hockey...
$86.98 canadian...

AND WE HAVE HOT HOT HEAT ON BOTH SIDES NOW!

(There might be a 1-2 degree difference but that is nothing compared to having lukewarm air vs blow dryer hot air like I did before)


To top it off, my engine idles like it used to. (since i've had the heat problems the engine has been revving higher than normal when parked or with the clutch down turning the corner. she's now back down to 750rpm in neutral and 1000 with the clutch pushed in when turning a corner. she was revving at 900 and 1500 when I had the heat problem. perhaps the poor flow was messing with the thermostat...)

Still can't believe the dealer didn't even offer this option and went straight for the $1200 replace heat core solution. Not happy about that at all!

Can't guarantee it will work for all but I hope my experience helps.

:)
 

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I had same problem. My problem was air mix motor assembly. Behind center console/dash. Part #79170-ta5-a21 $55 part. 1.5 hr labor. I did not replace. When I need cold air I turn it all the way low for 10 to 15 sec, then adjust. When I need warm I turn it to high and do the same. It seems when temp is turned to extreme it somehow regulates correct air mix. Its inconvenient but saves me from parting with $200.
 

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I had a similar issue with my 07 Acura TL. Previous owner had a dog so there was some hair that had gunked up the air mix motor. I took it apart and cleaned and added new grease, and fixed the issue by a large margin, but has never been quite as good as my lower km 08 Accord.

Maybe this heater core issue is also at play on the Acura. Might need a flush.

Bdeche, did that $86 Canadian include tax and new coolant? Coolant costs abiut $20 at my shop.
 

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2008 Accord 2.4 Auto EXL Dual Zone Climate Control 105k miles on car.

Blower works great on both sides
Mode control works great on both sides.
Tested with car fully warmed up.
BUT there is only heat on the passenger side. Drivers side is cold no matter if heat is directed towards feet, defroster, or top vents.

I have drained and filled coolant with genuine Honda Type 2 Blue coolant every 2 years since I purchased it.

After noticing this issue I just drained and filled the coolant again this afternoon.
Coolant coming out looked exactly the same as the new stuff going in. No change.

I took a flashlight and looked closely at the air mix/blend door actuator when I changed the temp with my other hand. They seem to both be functioning normally.

What are the chances that the heater core is clogged given my coolant drain and fills at 45k, 90k and now 105k?

Given the recent CRV TSB 14-063 for no heat on driver side vents see
2012 Honda CRV LX heater core - Page 2

Either I have the same clogged heater core problem as the CRV's...
OR
even though I can see the airmix/blend door actuator moving on the outside.... it isnt actually moving anything inside?? Anyone ever seen this problem?

Any other suggestions?
Thanks in advance.

Edit I just took off the actuator and moved the door control arm by hand, it is closing completely and when done quickly it makes that "thump" sound like when quickly changing controls from hot to cold or vice versa on an older cable operated setup...
Thanks for posting this. Had little heat on the drivers side for at least 2 years. I replaced the blend door actuator in the past, no help. Thought I needed to pull the dashboard to fix it. This was good to hear.
I was able to fix it easy using the following method: I pinched off the hoses with pinch off tools, pulled both hose from the heater core on the fire wall. I sacrificed a garden hose using the side that attaches to the garden hose, and a piece from the middle used as the drain. Rinsed through with radiator flush and saw some black fine particles come out. Poored the flush into the core thru the small hose I had attached, let the flush sit in the core for 20 min, then rinsed with fresh water for 5 minutes both directions. Blew the water out of core, then filled the core with Honda antifreeze and put the hoses back on. The heat is perfect and I didn’t have to add any fluid in the overflow just to the core. Isolating the core was magical. Worked great.
 

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Madiganistan/Chicago
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Discussion Starter #17
Thanks for posting this. Had little heat on the drivers side for at least 2 years. I replaced the blend door actuator in the past, no help. Thought I needed to pull the dashboard to fix it. This was good to hear.
I was able to fix it easy using the following method: I pinched off the hoses with pinch off tools, pulled both hose from the heater core on the fire wall. I sacrificed a garden hose using the side that attaches to the garden hose, and a piece from the middle used as the drain. Rinsed through with radiator flush and saw some black fine particles come out. Poored the flush into the core thru the small hose I had attached, let the flush sit in the core for 20 min, then rinsed with fresh water for 5 minutes both directions. Blew the water out of core, then filled the core with Honda antifreeze and put the hoses back on. The heat is perfect and I didn’t have to add any fluid in the overflow just to the core. Isolating the core was magical. Worked great.
Glad it worked for you!
 
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