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[Millerboy]

Hello peeps, got an annoying issue with the climate control in my '99 V6 CDX. The climate will provide heat at a set temperature for a short while after starting, for how long varies, and then it decides I'm warm enough and stops supplying heat. I've tried it on auto, manually controlling the temperature and the only way to stop the wife and kids moaning they're cold is to have it on hi and turn the fan down. It piles cold air in on lo and hot aair on hi. Just won't maintain a set temp. The sampling fan is working, there's no gas in the air con (suspect the condenser!) and before I changed the panel last year in an attempt to fix the same problem I got the dashes on the temp displays. Please help, I don't feel the cold that much but my passengers are moaning buggers but I love 'em!

[Kevin Wood]

Sounds like the sampling fan in the climate panel has packed up.

If you hold a little bit of tissue up to the vent in the centre of the climate panel does it get sucked onto the vent or just fall off?

Kevin

[Millerboy]

Thanks for the reply Kevin, I checked that today and it sticks like the proverbial to the proverbial!
Todd

[Kevin Wood]

OK. What about the outside temperature. Is that displayed correctly on the MID?

Kevin

[Millerboy]

Fixed that last winter, wire had broken. That's all working fine now. :-?

[Steveplumb]

Mine behaves similar, didnt notice it too much in the summer, but in the winter it tends to just keep  heating up and up... . Not trying to hijack this thread but is there a sampling fan on the facelift that i can 'do ' the tissue paper test on ? 

[Kevin Wood]

Facelift has the vent in the climate panel, but no sampling fan behind it.

On the PFL, when the fan fails, heat soak from the radio and panel lights make the panel think it's hotter than it is, so the car goes cold.

Other things to check:

Panels do get confused sometimes. reset them by holding down OFF and AUTO for a few seconds until the motors start whirring.

The blending flap linkages can fall off, causing a fixed hot or cold output.

Also worth checking the HBV and its' vacuum supply setup.

Failing that, get it on a tech 2 as there is quite a bit of live data available on the climate panel.

Kevin

[Steveplumb]

Thanks Kevin,   Is it ever the temp sensor itself behind the vent that fails ?

[sjc]

I had same on mine.  Stripped the climate control panel and found that the temp sensor was coated in fluff, dust and other general muck that has accumulated over the years.  Gave it a good clean up and all ok now.

Hope that helps.

[markrl]

Steve, the answer to your question re the temp sensor (thermister) going wrong from my experience would be yes it can. If I were you and your satisfied that the fan is working and the aperture is not full of dust then I would get hold of a late replacement second hand panel. A good one will sell for about £30-£35 on ebay. Although they look identical there are two versions of panel the late ones (from 1998 model year) have a small yellow dot on the back. As your car is a 1999 model this is what you will need. If you fit an earlier panel you will get -- -- on the panel displays. The LCD displays can easy be swapped over should your replacement one come with a few scratches from careless cleaning (as many do  ) I think this will be the easiest and cheapest way to sort out your very irrating fault. 

[sneakypenguin]

well it won't keep it at the exact temp you want because your a/c isn't working, when you press the auto button you may see the revs rise and feel the clutch/compressor kick but it can't do anything because of lack of gas, if you put it on normal/eco mode it will try it's best to maintain the temp but it won't be precise. On the flip side tho you shouldn't have the extreme in temps, as kevin said check the hbv (as that supplies the hot water(?) to the heater matrix, make sure it isn't leaking.

[markrl]

The original Op's point was that the system could not maintain a warm cabin and was going cold after a period of running. These are classic symptoms of a misbehaving climate panel usually caused by the poor drive electronics on the sampling fan. When the fan stops working or runs intermittently heat from the radio and dashboard panel bulbs misleads the climate system into thinking the cabins hot and it switches into cooling mode something which is not welcome when it’s the middle of winter.   

[Millerboy]

Wow, lots of replies, I'll pick out the ones that apply to me! Right, I've continued checking the sampling fan and when it's not sucking like a good 'un it's actually blowing out instead, I've turned the vents off above it to rule that out and it still blows the paper away, which is odd I think. When the system is on auto and it's deciding to chill me instead of warm me the cabin fan speed also increases, by quite some margin. On the occasions it's actually working the fan is very unobtrusive, as soon as it stops warming the fan steps up 2 or 3 speeds. Is this symptomatic with the poor fan drive electronics that markrl mentioned? The sensor was clean when I checked the panel a few weeks ago but if it was dirty surely it wouldn't warm at all instead of just for a short while?  :-?

[Millerboy]

Picking out from a post further up the list, does anyone know someone who has tech 2 in North Shropshire that wouldn't charge the earth to plug mine in?
Ta

[Millerboy]

Changed the HBV a few weeks ago, due to a leak, all the vacuum pipes are present and correct and have a vacuum as far as I can tell.