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Diagnosing Aircon Problems

freddofrog

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charlesa said:
Ok, thanks v much Freddo, I'm going to be out of reach for a few days on a boat. When I get back I will be in touch again.
Thank you so much for the time that you have taken to advise.
I'm driving 200 odd miles in the Accord tomorrow so I will do some more tests during the journey.
Bw C
No problem. Note that you can drive the car with it in diagnostic mode, you just won't see the "target" temperatures. but note that it's 14 presses from LO to HI so you can use it for heating e.g. do 14 "up" presses to be sure it's in HI then if you want say 24, do 5 "down" presses.
 

Sonoflal2

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So after a few weeks of monitoring my Aircon it seems I can only have hit and cold air separately, not together as you would normally expect to get a stable temp. I initially get cold conditioned air blasting from the vents when the engine is switched on then after a while when the coolant is up to temp I then get hot air blasting out for a few minutes, maybe 5, then it goes back to cold air again and that's pretty much where it stays. I took out the cabin filter and I could feel like warm air venting through there but had no effect on the cabin temp. Changing temp settings individually didn't make any difference to what air was vented where in the cabin. Seems I can't have warm air in the winter. One of the reasons I'm thinking of upgrading to a late model post facelift exec tourer instead.

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honda_saj

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Have you checked to see if air mixers are working ? One one on drivers sid by clutch and one on opposite side

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Sonoflal2

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The diagnostic shows both flaps move as the temp is adjusted. What appears to be an issue is both pipes into and out of the water control valve are cool. No hot water going into the matrix then even tho the valve opens and closes as it should and isn't leaking. Engine coolant temp peaked at 98 degrees this morning so that is getting up to temp ok. The big pipe going into the bulkhead directly above the water pipe is red hot but I don't know what that is to do with.

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honda_saj

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Faulty thermostat or blockage

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Jon_G

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If Freddofrog said that the heater matrix was blocked, then I'd believe him...
freddofrog said:
I don't know if they use a common sensor or not, but the valve should be either fully open or fully closed and if you're 100% sure that the valve moves from fully closed to fully open, then remove the pollen filter and see if that helps. If that makes no difference and the valve is fully open, then the heater matrix may be blocked.
In fact, are you sure that the whole engine isn't silted up, the i-CTDi should run at 80 not 98... the heater matrix gets hot initially until the silt builds up in the matrix whenever the engine is running again, like a blood clot causing a stroke.
 

Sonoflal2

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The engine didn't stay at 98 degrees, that was a peak value. It was usually around 83-85 degrees. If the matrix is blocked why do I get a blast of hot air to begin with that lasts for about 5 mins? If the matrix was blocked surely I wouldn't get any hot air. Unless the blockage moves away when the engine is off and the water isn't being pumped round then clogs the matrix as it moves through the system.

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Jon_G

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Leave both sides on HI all the time and keep checking the valve position as the engine warms up. If the valve is always open with temp always on HI and you don't always get hot air out, then something is wrong with the flow. In the ESM the thermostat begins to open at 76-80 C and is fully open at 90 C, so 98 C indicates a flow issue if the heater goes cold with the heater valve open. Maybe an air lock, could be anything, but not an aircon issue.
 

Sonoflal2

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So it seems I was low on water. [emoji15] Oops. All better now tho, lol.

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tonedepear

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Oh, how I hate photobucket. So many online car DIY threads ruined. I had this saved a while back, but I was having back surgery so had to wait a few months before I could get to trying to diagnose my accord's aircon woe, and here I am and all the pictures have gone. I don't spose anyone has any pictures of the accord (petrol) relay and bridging/battery wire before I try and do it from the text and **** it up?

Wonderful thread everyone, well done.
 

Ian.H

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Can anyone advise how to activate the built in diagnostics for the a/c please.
Thanks
 

honda_saj

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Freddofrog ? Are you around if not I can look up

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bigngroovy

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Hi, can't see photo's in this thread, is it my settings, or are pics no longer available?
thanks.
 

bigngroovy

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Is Freddofrog still on here? Does anyone else have pictures of which relay terminals to power up the compressor clutch from positive battery terminal? what about accessing self diagnostics menu?

Any help would be greatly appreciated. Thanks.
 

NugentS

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By request:

I managed to get hold of him on freddo dot frog at virginmedia dot com
 

honda_saj

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thats goods news has he left typeaccord not seen him on here for a while
 

honda_saj

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i have access to honda esm if anyone needs
 

honda_saj

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oh dear :huh:
 

elmo298

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Does the Sat nav on the cdti have a self-diagnosis for air con similar to the GPS diagnostics?
 

blaccord

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Good morning,
I had a problem with preasure sensor in my Accord diesel. Diagnostic shows error "R" and air-con diagnostic displays Error on position no 10.
I followed Honda ESM guides to check sensor wires and they looks to be fine, so I replaced sensor for new one from Ebay then re-gas air-con but still it does not working.
I am confused now there is problem with new sensor as well or some think else. Relay and compresr clutch are fine and working.
There was picture on this topic how to bridge sensor wires with paper clip to check sensor but it is not longer avalieble.
May any one knows how to bridge wires?

Best regards and thanks in advance
Dan
 

Scottydog

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Freddo great thread but I keep getting picture no longer available. Want to find out which relay in which box controls compressor clutch. My 2.4 petrol was ice cold this morning but when I came home the air was warm. Popped bonnet and could not hear clutch engage or disengage with she who must be obeyed turning ac on and off. Are these photos somewhere they can be seen?
 
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