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Discussion Starter #1
Hello

I have an issue with air conditioning / heat in my FN2 Type R (presumably same system as the MK8 Civic).

  • At first I had no air from my central vents. I changed the heater flap motor on the drivers side to no avail. However I was getting heat and air con (though not super cold) from the side vents.
  • Then I appeared to lose all cold and heat - only lukewarm air. I checked coolant (and after a slight panic as I thought there was oil in my coolant and my head gasket had gone ... but it was just a dirty cap) and it's up to the top of the radiator and seems green and watery.
  • I checked my cabin air filter (which I replaced a few weeks ago). It was slightly damp along the bottom and had a small red/pink mark on it (coolant leak? though it's a blue filter and my coolant is green - blue and green make yellow?)
  • I noticed that there was a heater flap motor on this side too - I had replaced the healthy one! I plugged the motor I had taken off into that side. My central vents now worked! However I had a new issue ...
  • I now get ice cold air from the passenger side and warm (but not hot) air from the drivers side. This is no matter if I set it to Auto or manual or what temperature or fan speed it is set at. The central vents seemed a little intermittent with the power of the air flow.
As you can see, all very odd. Anybody have any ideas? Will cross-post into Type R forum as well.
 

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Air con gassed up properly?

Relay working ok?

Coolant up to the level of the radiator and in the expansion tank? How many miles is your car on?

Cabin filter round the right way?
 

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Discussion Starter #4 (Edited)
Air con gassed up properly?

Relay working ok?

Coolant up to the level of the radiator and in the expansion tank? How many miles is your car on?

Cabin filter round the right way?
I don't know if the relay is working or not, but I ordered from eBay a replacement ac relay as I heard it is a common problem - for 6.99 worth a try.

It could probably do with a regas - I have had the car two months and haven't had it done, it has FSH but I can't see a note of it having been done previously - though surely I wouldn't get ice cold air at all if it was a problem with the gas?

Coolant right up to top of radiator. Expansion tank is really hard in the dark nights to see will check again this evening, failing which the weekend. Car is on 57k.

I checked this - arrows pointing into cabin, which I think is right!

Very strange sounds to be that the motor that directs the air to which part of the car is faulty , I’ve never had one apart but I assume it’s a simply open close system (flaps) maybe one is jammed ?
I'm wondering if it is to do with the blower motor I replaced tday. The part number is not quite right (one number is different), and the parts number for the driver and passenger side motors do not match either. Perhaps the motor only works one way i.e. the one I installed on the drivers side (and the one I removed from the drivers side and is now on the passengers side) should be round the other way - will switch them this evening to see.

I will have a poke around to see if flaps are working.
 

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based on the fact the pollen filter is damp, i'd go with the heater matrix is leaking. also since your only getting no hot air, that could be due to an airlock in the heater matrix. As the coolant system cools down, air has got in and now stuck.
i've not really looked at the 9gen heater unit (8&9gen are reasonably similar) so dont know if you can easily access the heater matrix for inspection.
a leaking matrix can lead to excessive interior condensation on glass. do you get that?

since the heat control is essentially just a flap, can you see/hear any movement of it as you adjust temperature?
 

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Discussion Starter #6
based on the fact the pollen filter is damp, i'd go with the heater matrix is leaking. also since your only getting no hot air, that could be due to an airlock in the heater matrix. As the coolant system cools down, air has got in and now stuck.
i've not really looked at the 9gen heater unit (8&9gen are reasonably similar) so dont know if you can easily access the heater matrix for inspection.
a leaking matrix can lead to excessive interior condensation on glass. do you get that?

since the heat control is essentially just a flap, can you see/hear any movement of it as you adjust temperature?
I cannot get cold air on the drivers side either - would the heater matrix cause that?

Or could I possibly have two problems - one no hot air (heater matrix) one problem with flaps (ice cold on one side only). Will check the flaps later tonight.
 

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I cannot get cold air on the drivers side either - would the heater matrix cause that?

Or could I possibly have two problems - one no hot air (heater matrix) one problem with flaps (ice cold on one side only). Will check the flaps later tonight.
i might of missed that about the no cold air. no, heater matrix wouldn't cause that. it does sound like a flap is stuck/broken.
i could be wrong, but i think coolant flows through the heater matrix all the time on dual zone models (unlike old/single zone cars that have a valve in the pipework to the heater matrix). The flaps inside the heater unit now direct air around the matrix.

this generic picture i found online shows how i believe it works. i think the pollen/cabin filter sits before the evap core on civics:



if it's not heater matrix causing the issue, it could be both flaps as the issue - one broken all together, one lazy that isnt fully blocking off the cold air side when you try to heat.
heater matrix should run around engine water temp - so around 80-90c when engine hot. one of those IR temp reading guns could be useful if you cant get close to it with fingers.

I'm not ofay with the civic heating system, so this is me trying to be helpful rather than experience with this type of fault.
 

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Discussion Starter #8
Thanks mate, much appreciated. I was wondering whether it was a flap that was directing all cool air one way and all hot air the other, hence adjusting dials not changing anything. However, not sure that explains the damp pollen filter and the inability to get hot air, only warm, out of the drivers side ... I will have a poke around when home from work.

The pollen filter does sit before the evaporator core - you can see it in the housing.
 

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Discussion Starter #9
I had a drive around this evening to try and resolve the problem. After a little bit of driving I did indeed get heat, but only from the drivers side (not sure if it was getting as hot as I would expect though). I was getting cold from the passenger's side. The fans and temperature controls are pretty hit and miss and it's never quite clear what they are going to do next.

I also noticed that I get a whirring noise when my windscreen heater is going full blast. A quick Google suggested alternator / aux belt as a cause.

This got me thinking - very occasionally I get an odd flickering of my dash lights. Could the alternator be the cause of all these odd issues? I.e. not enough juice to work the flaps properly etc.

Or do I just have twenty different problems.

I think a trip to a garage is probably in order.
 

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I have worked it out. I am an idiot.

It is the heater flap motor. In installing the one on the driver's side, I just plugged in the wiring loom - and didn't actually attach the arms that control the flaps. Indeed, I removed them as they got in the way (though this appears to be because the part I have is somehow wrong - the arms are not the same). As mentioned above, it was the passenger side one that was faulty, not the driver side - and I didn't remove the passenger side one, again just unplugged it and plugged in the new one. Obviously, nothing happened.

So, I need to buy two heater flap motors that actually fit, and install them properly. I don't think I can remove and install the passenger side one without removing the glovebox/dash however, which I am not sure how to do.

Suitably embarassed ... hopefully once sorted the issues will be resolved.
 
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