Menu
What's new
By:
Advanced search...

Blowing hot and cold air

J

jpacoupe

Members
Messages
41
Reaction score
3
Location
near croydon
Car
accord
Climate control went silly today. The drivers side blows hot air no matter what temp you set it to, while the passengers works fine, hot or cold. Doesn't matter if it's on the vents, screen or feet, drivers side is always hot. Even with no fan blowing, the air coming through the central vents is heated on the drivers side..

Any ideas?
 
The evaporator is on the left hand side so the cold air tends to be "biased" to the left side when A/C is weak

The system either needs re-gassing, or the condenser is badly perished, or both.
 
Thanks, but would that make the drivers side hot, I don't mean not chilled, it's actually hot like it's set to full heat..
 
That might be a bit different

The system is "climate control" which means that, unless you manually turn off the A/C (which stops the compressor completely), then the system "blends" cold air from the evaporator and hot air from the heater matrix, all the time.

So in normal operation in mild temperatures, both the A/C and the heater matrix are fully on. The only way to be sure that the latter is turned off is to set the target temperatures to LO, this will close the valve on the hot water inlet to the heater matrix. Maybe try that but it won't really prove much anyway.

The only other possibility is that the mixture flap on the driver's side is stuck, but this turns out to be extremely rare, and the cause has usually turned out to be low A/C efficiency.

There are a couple of very good threads on this that I will try to find.
 
Interesting my brother was complaining his cl7 EuroR is doing this since last week although it's warm air rather than hot from one side. His aircon is low on gas so maybe that's the cause
 
Last week the car was in the Honda dealers for the passenger airbag recall.
Is there any way it could be related?

It's the fact that it's blowing very hot air that's odd,
Even with the climate fully off, the air flowing through the vents is heated on the drivers side, which makes your something stuck open suggestion sound possible.
 
jpacoupe said:
Last week the car was in the Honda dealers for the passenger airbag recall.
Is there any way it could be related?

It's the fact that it's blowing very hot air that's odd,
Even with the climate fully off, the air flowing through the vents is heated on the drivers side, which makes your something stuck open suggestion sound possible.
Click to expand...
In answer to the air-bag question, not if the passenger side is working ok

The system is quite simple, but has subtle nuances that are difficult to explain (even with the diagrams)

As I say, there is an evaporator (cold source) ad a heater matrix (hot source). Both of these are either on or off, no "in-between". In normal target temperature ranges they are both on all the time, but you can hear the valve on the heater matrix being turned on or off if you ramp the target temperatures up and down and know what you're listening for. The evaporator is always a cold source unless the compressor is off, and the only way to turn the compressor off is to manually turn off the A/C. If the A/C is not off, then you can hear the compressor coming on and off, but if the A/C is low on gas (or condenser is perished) then the amount of cold air is limited, and biased towards the passenger side.

Even when you turn the whole thing OFF you will still get air-flow over the evaporator and/or through the heater matrix, which seems very strange until you know how the system works. With the system OFF the compressor is no longer running, so the cold source stops sooner than the hot source (because the latter has thermal mass).

With the engine cold, set the target temperatures to LO, and then you should never get any hot air from any vent, but as soon as you raise the target temperatures sufficiently, the valve to the hater matrix will be opened, and then there is a hot source. That source has thermal mass, so even if you turn the system OFF you will still feel hot air for quite a while.

There's a built-in diagnostic system, I'll dig out those two threads in a bit.

(btw I had to concentrate a lot when typing hot source LOL)
 
thanks for all the info.

i think i'll have to book it into the dealers for diagnostics though, I haven't got the patience or ability to have a go at this myself.
 
jpacoupe said:
i think i'll have to book it into the dealers for diagnostics
Click to expand...
before you do that, take it to an independent aircon specialist (or a Halfords service centre if there's one in your area) and ask them to test the gas pressure

note: Halfords service centre is like a garage attached to the store, an ordinary Halfords (without a service centre) might also check the gas pressure as well. But only ever go to a dealer to get them to "diagnose" anything, especially aircon, on a 7th gen Accord, as a last resort.
 
Apparently one of my flaps is stuck !

The one that diverts hot and cold air needs replacing,

Its not a big part, but a lot of the dash needs to come out to fit it, so labour will be more than the part.
 
jpacoupe said:
Apparently one of my flaps is stuck !

The one that diverts hot and cold air needs replacing,

Its not a big part, but a lot of the dash needs to come out to fit it, so labour will be more than the part.
Click to expand...
I presume that a dealer said that

79160SDC941 £111.99

Labour £100 per hour, couple of hours if you're lucky

after VAT, should come in under £500

good luck with the wallet and let us if they were correct
 
If they had ordered the right part last week it might be fixed now, unfortunately they ordered a flap for a 2.0, and mines a 2.4.

2.4 flaps are not in stock so i have a 3 week wait.

Oh for flaps sake...
 
I'm surprised they're even different to be honest.
 
i agree, it doesnt seem worth engineering two types of flap,

or should we say good for honda for not compromising and having attention to detail when designing these things ?
 
without bothering to look, the 2.0 and 2.4 will be same part, because the entire A/C system on the 2.4 and 2.0 is identical in every way.

does not inspire one with confidence does it, because I say they are wrong

will they give you your money back if they replace it and it changes nothing ?
 
does anyone have a parts list?
if i can see that the parts are the same for the 2.0 and 2.4 i'll go back and get them to explain themselves.
 
Heater unit for Accord Tourer 2004 2.4 Exec https://www.lingshondaparts.com/honda_car_parts_selection.php?block_01=17SED01&block_02=B__1721&block_03=529&block_05=hcr

Heater unit for Accord Tourer 2004 2.0 Exec https://www.lingshondaparts.com/honda_car_parts_selection.php?block_01=17SED01&block_02=B__1721&block_03=515&block_05=hcr

As I predicted, the parts lists are identical for 2.4 and 2.0 (because the two cars are virtually identical at the same trim spec)

If you want to make your own comparisons start here https://www.lingshondaparts.com/honda_car_parts_catalogue_C01.php

when you open a page with the part numbers displayed, you will see that the part numbers begin with "PFKL", remove "_pfk" from the url to get proper Honda part numbers (as I have done in the two links top of this post)

btw, If you never took the car to an independent aircon specialist, or Halfords even, then you are starting to discover what everyone eventually comes to realise, which is, only take an Accord to a Honda dealer for any kind of "diagnosis" as a very last resort (preferably never at all).
 
The dealer has been told "thanks, but no thanks".

especially as the thing has started working again.

if it happens again in the future, a) i will know what it is, b) i'll get it done at an independent AC place

thanks for everyones advice
 
Glad it's working again ;) If it's been re-gassed then that's why it's working ok again

tbh in all the time I have been on this forum (and, on a couple of occasions in the past, I myself have suggested that it might be the motorised flap that has gone wrong) there has never been a motorised flap failure, the described symptoms have always turned out to require a re-gas or a new condenser or a new pollen filter.

The rule is, particularly with aircon issues and in general even with Honda, never take a car out of warranty to a dealer unless it's something bog-standard like a clutch etc. We've all come to that conclusion in our own (bitter) experience and also by reading the misfortune of others.

If it goes wrong again, honestly the self-diagnosis in the aircon on the 7th gen is a doddle to use, a fabulous hidden gem in the car.
 
"If it goes wrong again, honestly the self-diagnosis in the aircon on the 7th gen is a doddle to use, a fabulous hidden gem in the car."

that sounds interesting, can you fill me in?
 
this image explains how to get into the aircon diagnostic system (click on the image to enlarge)



SEA3E50K71100000000BBAT00_4.jpg




The only "difficulty" ergonomically speaking is that, when in diagnostic mode, you can't see the "target" temperatures in the upper display (satnav car, which you have). This is because the upper display shows the value from the selected sensor instead.

Best thing is to practice "blind" setting the target temperatures when in normal mode i.e. start with the target in LO then count how many presses of the red "up arrow" it takes to get to HI, so that you can set any desired target temperature "blind" by counting the up/down presses from LO.

Then set the target temperature to LO, switch off the engine, and follow the instruction in the image above.

You can drive the car while the system is in diagnostic mode and look at any sensor.

For "sensors" 6 and 7, as you change the "target temperature" (blind) you should see the flap % change.

Sensor 9 is strange, I think it is "virtual", and is a function of "target temperature" minus "in-car temperature"
 
Hi guys,
I've been advised that my aircon isn't blowing into the cabin as I do have a motorised flap failure. The system is fully gassed and the compressor replaced. They claim that it's 12 hours work to get to the flap and therefore not worth their time or my 1500 quid, plus an additional £800 plus VAT to replace it.
Guess I'll just leave the roof open! :)
 
freddofrog said:
Glad it's working again ;) If it's been re-gassed then that's why it's working ok again

tbh in all the time I have been on this forum (and, on a couple of occasions in the past, I myself have suggested that it might be the motorised flap that has gone wrong) there has never been a motorised flap failure, the described symptoms have always turned out to require a re-gas or a new condenser or a new pollen filter.

The rule is, particularly with aircon issues and in general even with Honda, never take a car out of warranty to a dealer unless it's something bog-standard like a clutch etc. We've all come to that conclusion in our own (bitter) experience and also by reading the misfortune of others.

If it goes wrong again, honestly the self-diagnosis in the aircon on the 7th gen is a doddle to use, a fabulous hidden gem in the car.
Click to expand...
freddofrog said:
this image explains how to get into the aircon diagnostic system (click on the image to enlarge)



SEA3E50K71100000000BBAT00_4.jpg




The only "difficulty" ergonomically speaking is that, when in diagnostic mode, you can't see the "target" temperatures in the upper display (satnav car, which you have). This is because the upper display shows the value from the selected sensor instead.

Best thing is to practice "blind" setting the target temperatures when in normal mode i.e. start with the target in LO then count how many presses of the red "up arrow" it takes to get to HI, so that you can set any desired target temperature "blind" by counting the up/down presses from LO.

Then set the target temperature to LO, switch off the engine, and follow the instruction in the image above.

You can drive the car while the system is in diagnostic mode and look at any sensor.

For "sensors" 6 and 7, as you change the "target temperature" (blind) you should see the flap % change.

Sensor 9 is strange, I think it is "virtual", and is a function of "target temperature" minus "in-car temperature"
Click to expand...
hi could you please explain how to use the heater diagnostic system? i cannot see the pic you attached. thanks
 
You must log in or register to reply here.
Top