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Cold Heater

Petercarman

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Hi,
the heater on my diesel tourer is very poor, luke warm on the passenger side and cooler on the drivers side.

It has been suggested that the thermostat needs replacing.

Does anyone hve any knowlege about this and and the ease or difficulty of replacing the stat.

Cheers, Pete.
 

freddofrog

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The thermostat controls engine temperature, and so that is a possibility for the heater being cold, but there are other possibilities too.

See the post in this link (don't bother with the rest of the thread in the link) http://typeaccord.co.uk/forum/topic/21792-air-con/?p=232636

You will see that there is a built-in diagnostic in the A/C unit, and it shows several sensor values, including the engine temperature. The latter is sensor "A" (the tenth in the list) if you monitor that sensor you will be able to check the engine temperature.

If the engine temperature is normal (should climb to about 80 C) then there are several other possibilities, i'll go through those if the engine temperature is not the source of the problem.
 

Petercarman

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Hi Brian,

thank you for your reply and the information regarding the aircon test procedure.

I have been out in the car this afternoon to check the coolant temperature with "Torque" App. After warm-up it recorded temperatures of lowest 79c and highest 83c which seems to suggest the thermostat is O.K.

Yesterday I took the car to my local Honda dealer for repair under warranty, only to find out it was not covered due to the recorded mileage, it was them who seemed to think it had a faulty thermostat.

I would welcome hearing the other possible causes for this fault.

Cheers, Pete.
 

vile

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Hi Pete when was your pollen filter changed as this can result to your problem.
 

freddofrog

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It cannot be the thermostat if the engine is reaching the correct operating temperature (which it is).

One of the possibilities is indeed the pollen filter, remove the pollen filter and see if that helps.

If it does not help, run the inbuilt diagnostic and note all the other sensors when the engine is at operating temperature, with A/C ON and "target" temperatures set to HI.
 

Petercarman

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Thank you Brett & Brian,

I will check the pollen filter and let you know the outcome. It will be next week as i have other plans for the Weekend.

Pete.
 

vile

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Also Pete to check your thermostat is working run your car on tick over until the fan kicks in with the heater on high.
Don't put the fans on as it will take forever to get to temp.
If your thermostat is working when the fan kicks in your lower coolent hose will get hot as the thermostat is opening and taking heat away from the engine to cool it.
Another thing could be your heater matrix but you normally loose coolent if it's shot.
 

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His thermostat is ok Brett, because the temperature is more or less stable around 80 C, and I doubt if the heater matrix is leaking because if it is, the water level will very soon go low and then he will know about it.

The first check is to simply remove the pollen filter and try the heater without the pollen filter when the engine is at operating temperature (80C).

If that does not help, then he needs to check all the sensors from the inbuilt diagnostic, again when the engine is at operating temperature (80C), because it will then be either an issue with the flaps, or a stuck valve on the heater matrix, or a blocked heater matrix.
 

Petercarman

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Hi all,

I have run the tests as suggested in the link you gave me and the results are thus:-

1 = 50
2 = 19
3 = 09
4 = 00
5 = 03
6 = F0
7 = 99
8 = 32
9 = 00
A = 80
B = 93
C = 09
D = 01

As you can see that the engine temp is 80c (normal)

The passenger air mix is 99% (No.7), but the driver air mix (No.6) reads FO or F0. Does this mean that this sensor is faulty?

Hope you can help, Pete.
 

freddofrog

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Hi, F0 is ok, it means that the flap has rotated slightly past 100%, nothing to worry about.

The "climate control" in these cars works by mixing air from the cold source (the evaporator) and the hot source (the heater matrix), so when at 100% , the flaps are set to provide air from the hot source.

Sensor B also indicates that the system is trying to provide max heat (where the description in the link says it is deg C, it isn't, it's a virtual number which is some multiple of "target temperature minus in-car temperature").

All the other sensors also seem to be providing reasonable numbers (although I don't know what C and D represent).

So we are left with 2 possibilities
1. a fault ***ociated with the flow of air into the heater core
2. a fault ***ociated with the heater matrix

For item 1, try it with the pollen filter removed i.e. just remove the pollen filter, and put everything back without the filter, and see it that solves the issue
For item 2, the valve providing the engine water to the heater matrix is either open or shut, and you will need to visually check if it moves from one position to the other when you alter target temperatures from LO to HI and back again. I'll explain more if removal of pollen filter doesn't cure the problem.
 

Petercarman

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Thanks Brian,

I will do as you suggest, but it will be Wednesday before I can try the filter removal.

Cheers, Pete.
 

Petercarman

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Hi Brian,

managed to find some time to-day to remove the pollen filter, it was very dirty with the odd bit of leaf so my hopes were up.

However a 55 mile run home showed no improvement to the luke warm heater.

Any further advice would be very welcome.

Pete.
 

smokingman

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Hi.

The heat out of my tourer is not that brilliant at all either, in fact nor was my previous Renault diesel compared to the petrol equivalent. So maybe this is just normal!!
 

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The diesel Accord takes longer to warm up than the two petrol Accords, mainly due to larger thermal mass, so the heater will not be as warm in the diesel Accord on short journeys.

But once the diesel has reached operating temperature (80 C) there should be no difference, it should blow as hot as on a petrol model.

Note that in very cold climates, when the outside temperature is <5C and the engine temperature is <70C, the diesel Accord uses the evaporator as a hot source (A/C becomes a heat pump for the cabin) until the engine begins to reach operating temperature.
 

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TourerFan said:
Hi Brian,

managed to find some time to-day to remove the pollen filter, it was very dirty with the odd bit of leaf so my hopes were up.

However a 55 mile run home showed no improvement to the luke warm heater.

Any further advice would be very welcome.

Pete.
I just realised that I didn't answer your question.

Did you try it with the pollen filter removed, and was the temperature at 80 C ?

If yes to both, then now check the valve on the heater matrix.

With target temperature set to HI the valve should be as in the picture below (it's on the bulkhead at the back of the engine, note that this pic is from a 7th gen petrol Accord)





With target temperature set to LO the valve should be as in the picture below



If that valve is not moving, that is why the heater is cold (***uming airflow is not blocked and engine is at operating temperature)
 

Petercarman

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Hi Brian,

I have been checking the heater valve this afternoon (I guessed it was the device on the engine bulkhead) and the bowden cable has only a small amount of the inner cable showing, as in the second picture, but the orientation is such that the operating nipple is at 5 past the hour instead of 25 to the hour, as in your picture.

When I adjusted the target temperatue from Hi to Lo and then from Lo to Hi the cable did not move.

It was late in the afternoon and getting dark so I will investigate more in the morning.

If I need to check the other end of the operating cable how easy is it to gain access to the heater unit.

Thanks for the information and the 2 pictures

Cheers, Pete.
 

Petercarman

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Hi,
checked the water valve operating cable today and found it would move by hand from 5 past the hour to 20 past the hour.

With the actuator in this new position took the car for a run and found the heater worked fine giving plenty of heat after only 3 miles.

I disconnected the inner cable from the small actuating nipple and found that the inner cable could be moved easily back and forth, suggesting it is not attached to anything at the other end.

The next step is to look at the other end of this bowden cable and any advice regarding access would be gratefuly recieved.

Pete.
 

freddofrog

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Phew, that's the problem "solved", some good detective work there too

AFAIK you should not be able to move the cable by hand, so the cable has probably come detached from the drive unit at the far end. I personally have never seen the drive unit, but someone told me that it's located on the driver side (UK) somewhere above the pedals.

If you manage to find it, let us know, you're trail-blazing from here on ;)
 

freddofrog

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In case you take any pictures and want to "display" them, you'll need to upload them to a "photo-hosting" website such as http://photobucket.com/ and then use the "share" features on the hosting website to get the appropriate links.

btw the only reason my pictures above are "water-marked" is because a few years ago I started a long thread on 7th gen A/C issues (not the heater) and I water-marked them at the time (IIRC those pics above were in that thread but they're in several threads on TA)
 

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Hello guys, i just began testing my thermostat too, i think it is opening a bit soon, because when engine is at 60C degrees both upper and lower radiator pipes are warm, in addition to this, thermostat should be open at abdout 78degrees.

Anyway when i started to look at thermostat prices, i noticed that there is two different variants of thermostats, one is 82C opening temperature, and other 78C temperature. In dimensions they are identical. The main difference is make model year, where 82C thermostat come in later 2012 year accords.

Does the engine is different in 2012 year? If no, then i will buy 82C thermostat, where it should open later, thus it should get warmer quicker :)

I live in Lithuania, so i can get both thermostats,

and here is the other link in your main land: http://www.onlinecarparts.co.uk/spare-parts/honda/thermostat/accord-viii-cu/34928.html
 

Petercarman

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Hi all,

I have finally got to the bottom of my cold heater problem. The inner cable that operates the water valve was not attached to the plastic actuator on the heater/aircon. Unit.





To gain access the panel under the steering column needs removing along with the one to the left of the foot rest by the side of the clutch pedal. Access is very restricted and I used the tools below to perform “Key Hole” surgery.



This is the inner cable on its actuator after considerable effort with the forceps and the big screwdriver







With the heater set to “Hi” look under the bonnet and the water valve on the bulkhead should look like this.




Set the heater to “Lo” and it looks like this.




Note: I removed the centre console, heater controls and C.D. Player for better access but found that the dashboard “skeleton” of very hard plastic or could be carbon fibre, prevented any access from the front.
Hence the struggle via the side panel.

Hope this helps anybody else with a luke warm heater, Pete.
 

smokingman

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Hi

Looking at your 5th picture TourerFan, there seems to be a barb on the plastic peg which seems to be depressed, though stress damaged. It looks like it's there to stop the cable coming off in the first place. Maybe you could place something under it so that it stops the cable coming off in the future.

John
 

Petercarman

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Hi smokingman,

I think you are probably right.

This was only noticable when I zoomed in on the picture I took and by this time I had put everything back together.

If the problem reoccurs then I will do as you suggest.

Cheers, Pete.
 

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Hi Pete thanks so much for putting this together, my heating has been cold for a while and thanks to your photos I have been able to at least manually actuate the cable so that it blows hot when needed. Surprising that I need it in June, but there you go!

Can you explain how the bits of trim are removed? It is so cramped and dark in there I am worried that I'm missing some clips or screws. I haven't seen any of either yet!

Thanks, Paul
 

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OK I had another look in the daylight and in fact all I needed for access was to remove the lower panel below the steering wheel which is just a case of gently pulling off the point where it hooks on at the back of the panel (nearest to the pedals).



If you carefully unplug the plug from its socket in the panel, you can fully detach the panel and move out of the way.

Then you can shine a torch into the area behind the heating controls and see the offending cable which in my case had indeed become detached from the white plastic barb which is supposed to actuate the cable.





I reattached the cable and then also squeezed in a length of zip tie between the barb and the cable end which I am hoping might make it a bit more secure. I reckon a smaller zip tie would actually loop around the cable end and the plastic barb but I don't have one available to try.

Thanks again to Pete for working all this out.
 

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I know this is an old thread, but im gonna try this tomorrow. I have noticed over the last two weeks that there is very little heat coming through the vents on HI setting.
 
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