Heat Problem, blows cold on passenger side
 

Hi All,

So, I searched and searched and searched a bunch of websites including this one to no avail. I have a 07 Civic EX, and when I turn the heat on, it comes out very hot on the far drivers side dash vent. Slightly cooler to the one to the left of the radio. Even cooler to the right of the radio, and air temperature on the far passenger side vent. It blows warmer on the drivers side than on the passenger on the floor as well. The mode control motor is working fine, and the temp control seems to be working fine as well, as it will go to cold no problem. I flushed and blew out the heater core to make sure it isn't clogged. The A/C works. The car is not equipped with dual zone climate controls. I'm at a loss, and cant afford to have honda charge me $2k to take the dash out to replace a $5 part. I live in Boston, and it is quickly getting cold here.

Is there a door that changes it from blowing through the heater core to blowing through the A/C evaporator? The one thing I noticed is that with it set to full blast heat, if you turn on the A/C, the air will get colder out of the passenger side vents. I need some help here guys. If anyone has any idea, Id appreciate the advice. Thanks.

Re: Heat Problem, blows cold on passenger side
 

I'd wild guess a partially restricted or partially blocked heater core.

A HECAT pulsator flush gun may be more effective than a simple garden hose flush.

Re: Heat Problem, blows cold on passenger side
 

Well, I did the garden hose flush, then blew some compressed air thru both lines. Doesn't seem to be any restriction, but I'll look into where I can get one of those flushers.
Is there a door that swaps the air flow from the heater core to the evap core? All I can think of is maybe it's not closing all the way, allowing evap air to pass thru even when it's set to heat. If such a door even exists. I can't find a diagram that really shows how that system works.

Re: Heat Problem, blows cold on passenger side
 

Yes there are doors (I'm not sure if the temp control is technically a 'door') but it can't close off heat for one side of the car by itself.
That's why I guessed it's a core problem.

Re: Heat Problem, blows cold on passenger side
 

Ok thanks. I'll try to find one of those flushers, and I'll report back. Appreciate it.

Re: Heat Problem, blows cold on passenger side
 

Well, I was told of a cool test to see if it's the heater core. Turn the heat off for a few minutes, then turn it on. If it comes out warm from all vents, then gets cold, the heater core is partway clogged. The above mentioned hecat costs a fortune, but this tool http://www.amazon.com/gp/aw/d/B000F5...pCL&ref=plSrch costs a fraction of the price and worked great. Heater core is un clogged and heat works great. Thanks for the help guys

Re: Heat Problem, blows cold on passenger side
 

I searched for "Keyword(s): dash, heater, vent" and a few threads caem up, this is one of em. My 2015 LX heater, when set on dash&floor vent setting barely blows any air out the dash vents, this morning at -20C it was virtually no air in my face.
I'm wondering if it's a common problem now, just when on that particular setting. The other settings seem to work fine, and when on dash vent setting only it blows alot out them. Not really a headache but even my 98 Accord worked much better!

Re: Heat Problem, blows cold on passenger side
 

If you turn off the passengers vent, you may gain a bit more air flow from the other 3.



My 12 is similar, and I usually keep it on floor/dash most of the time in cold weather.
I do kinda wish there was fully adjustable controls for air distribution, but they didn't give us that ability.

Re: Heat Problem, blows cold on passenger side
 

I'm hoping to see others with the same reaction on this model or this generation car, then decide if it's an actual defect or simply something we have to live with. I want to be prepared with some facts before I complain at my dealer.

In the same breath I won't accept closing other vents and freezing my passenger to compensate for more flow on the driver's side, if my dealer suggests that I'll be making a call to Honda Canada.

Re: Heat Problem, blows cold on passenger side
 

Go to the dealer, test drive another identical car from their lot?

Re: Heat Problem, blows cold on passenger side
 

Hello my name is David I'm having the same problem hot air in the driver side and cold air on passenger side I flush the heater core with a hose garden & Air. No difference.... the tool that you describe you think it's going to work???

Re: Heat Problem, blows cold on passenger side
 

I have not used that particular tool. I do know the tools and equipment from HECAT are top quality, and the owner of the company participates in a professional forum I am a member of.
I think if you do some searching you can find similar tool options at lower prices, but I'd expect the quality may not be equal.



Copied from another recent similar thread:

Check CRV forums for 2012-14 with poor heater output.....There was a whole bunch that had some sort of trash that ended up trapped in the core, and caused a partial blockage inside the core.
(some people have said it was leftover casting sand, others have said it's residue from the long life coolants)

It also caused a noticeable temperature difference between drivers and passengers sides.

Honda has a service bulletin outlining a pretty intense flushing procedure for the issue on those CRVs. Even though the bulletin only listed CRV specifically, other cars have needed the procedure.

This is the equipment I personally have used in our shop.
The work for those involved a large electric pump connected to the heater core, 5 gallon buckets, a half gallon of C.L.R. per car, a bunch of water, and a bunch of time.

Re: Heat Problem, blows cold on passenger side
 

Hello All so i have 2007 civic and i also have a same problem i change the thermostat and flush the coolant with machine but no result driver side vent hot air and pass side cold what i am thinking it may be heater control valve but i dont know if civic has because i searched it and did not find anything . if you guys find out the solution of the problem then please post it here i think so many people have that problem its -30 out here where i live u know how i feel when drive lol.

Re: Heat Problem, blows cold on passenger side
 

Did you read reply #6 in this thread?

Re: Heat Problem, blows cold on passenger side
 

today i flush the heater core did not effect any same problem the gun i think it produce more pressure i read some where on forum more than 10 psi pressure will may damage the heater core just the heat on driver side getting more better after the heater core flush i think i have to dig out the dash for the problem. because #6 he mention that i to close the heat and then open it check all the went i did the test but i it dont seem i have the same problem because it did not change its something else bow i have only option to dig out the dash if u guys have some idea how to take apart the dash then please post some links

Re: Heat Problem, blows cold on passenger side
 

The entire cooling system will run up to 15 PSI (or whatever the radiator pressure cap says on it) while driving normally.
You can go that high with a flush too.

If you gained a little improvement so far, I might keep doing it to see how much more improvement you can get without pulling the dash out.
Flushing is pretty easy IMO. Pulling the dash out is a whole lot of work I don't really want to do. (I'm lazy)

Re: Heat Problem, blows cold on passenger side
 

covic0 .. if you find the problem please let me know I live in apartment here in Wisconsin ,and I don't have garage to take dash a part... someone told me to change the cabin filter to help heater....so I changed..but no difference.....good luck..

Re: Heat Problem, blows cold on passenger side
 

i have 08 civic ex with same issue. New heater core based upon dealerships input, damn. Guess I didn't need all that $$. I'm not going back to dealer. Same issue. Driver side dash vent hot gets colder as you move to passenger side with far right vent blowing cold. Is there a door that could cause? AC is fine just need heat.

Re: Heat Problem, blows cold on passenger side
 

Had to do the described flush to a 12 CRV today and got a couple pics, first two are the pump (its hoses are already connected to the heater core pipes at the firewall, backflushing or backwards flow through the core), the bucket with one gallon of water and half gallon of CLR that is being circulated through the heater core, and the last pic is the same bucket after the flush period is over (I let this one run for at least 2 hours) with maybe a couple more gallons of water in it:

Attachment 113767

Attachment 113768

Attachment 113769

Attachment 113770

Yeah, that garbage stuck to the sides of the bucket and in the water came out of this CRV heater core. I'm pretty sure this bucket wasn't THAT dirty when I started.

Re: Heat Problem, blows cold on passenger side
 

^^^ Has the '12 CR-V ever had a coolant service done ??

That is a lot of crud.

Re: Heat Problem, blows cold on passenger side
 

Shouldn't matter, because the first scheduled cooling system service is 10 years/100k miles or something close to that. Pictured was a 2012 CRV with only 70k on it. Approximately a 40 degree (F) difference between the drivers outer vent and the center vents with the engine warmed up, heater temp on high and fan on full blast.
(EDIT: this car actually came from another shop that wasn't able to solve the problem, and they apparently topped up the radiator with some green coolant after their attempt at flushing or whatever they did.....but this is not a new or unique issue, and it's happened to some of them quite early in their life)

The bulletin only describes the condition as being caused by a partially clogged heater core, it does not say specifically what the clog is caused by.

I just scooped a hand into that bucket now that it has settled overnight: the stuff is not grainy, it's more like slime. (But remember whatever is in the bucket has likely been dissolved by the CLR so I can't tell what it started out as.)

Re: Heat Problem, blows cold on passenger side
 

^^ Scary.... one step forward, two steps back.

Re: Heat Problem, blows cold on passenger side