S40: blowing in hot air even set on cold

[richysb]

I have had the same problem.

I found a potentiometer and swapped it out. Still no good.

When replacing the unit in the dashboard I pushed the cables going to the larger of the two plugs (bottom left looking from the front) and the heater control started working again, Let go and it stopped.

I now have a piece of plastic pushing this plug up at the bottom left and the heater control is working fine!!!!

Looks like it could just be a dry joint or loose connector in the plug. I am going to check out in more detail when I have more time but until then, I have hot and cold as and when I want them!!!!

[RandomGuy]

Originally Posted by hobbo

There is no clicking noise that i can hear. Thanks for the advice I am dreading taking the dash apart so will check what I can get too. I think the whacking the top of the dash on the passenger side will have to do until it stops working. Then pay out loads to find the problem.

Just found this, tried the slap-dash solution, worked a treat.

Thank you soo much, heaters been really bugging me, especially with the winter coming again.

[pierremcalpine]

Originally Posted by sebaveh

Potentiometer is not such exotic part to get. Every local electronic store should have it - or order it, if it is not on their stock.
It is just regular 5 K , vertical, size PT15 with big hole for axle. But you will have to bend the center or both lower pins. Compare boh old and new one, and you will see why.
Another thing that must be done is the adjustment of axle. Because potentiometers come with 20% tolerance in resistance, and not two are the same. Climate units are built so that are soldered first and programmed later. That means the each program (firmware) is also set for potentiometer specific tolerance. And if you change potentiometer with another one, you may have a little error in position. You won't feel that error in temperature knob (unless you measurre the exact temperature, which is pointless for +/- 1 °C); but you can see it with fan speed knob.
I changed both potentiometers on my automatic climate module. Of course, new potentiometer had different tolerance as original. Result was, fan was turning on position 0, but it stopped somewhere between AUT and 0. So what I did - took the fire lighter and heat up knob axle, then twist it just a little bit and try it again. After 3 tries, I got it all set. Well, there is still non-linearity in speeds (it misses 3,5 and don't reach full 5, but 4,5 only), but I don't care that much. As long as AUT and 0 works fine.

Sorry for lond writing, but you get the idea.

I just finished the same job and noticed that the first position on the fan dial is the "0" verses "Auto." I've taken a good guess at how much a need to twist the plastic axle but have not had any success finding the right gizmo to heat the thing up...just so I'm clear, you used your car lighter? Not a bad idea. I was thinking of going with a heat gun (as I don't have a lighter)...wondering whether that would be too much fire-power though.

Funny thing is that at first I thought I had royally messed up the re-soldering job on the new potentiometers because my air conditioning would no longer turn on when the fan was set to "auto." It was only an hour later that I figured out that "auto" was in fact "0" - a setting where a/c turns off automatically, due to the potentiometer being set differently than the old one.

[S40isGreat]

2009 S40 2.0 right hand drive

It happened to me a second time yesterday. The first time it cleared on its own after a week or so; I wasn't prepared to wait this time. I switched the car on, switched both sides temperature to 30 deg C, put the fans on full and left the doors closed for five minutes. Then opened the door, switched the aircon on, dropped the temperature setting to minimum and both sides started blowing cold. Pro-tip, don't stay in the car while the doors are closed unless you are in Sweden in the dead of winter buried in a snow drift.

I suspect that the temperature control on the drivers side got stuck at a stupid high value and the driver side climate control was trying to bring ambient temperature up to that level, so I let it and hoped it it would be satisfied and would allow changing the temperature to a lower level. Whether or not I guessed the problem and/or the solution right, this worked for me.

[druid]

Not only is the post at least 2 years old, its also for '95-'04. you would do better in the http://www.volvoforums.org.uk/forumdisplay.php?f=58 section.

[volvo for ever]

sorry wrong model

[MikhailN]

Hi,

I have a similar issue.

I had aircon gas checked.

My aircon blows hot air during middday when you need the cool air most.

Any ideas/suggestions?

[Simpo]

Hi all I have a 2011 v50 and the heater blows hot or cold nothing inbetween. Can anyone help on this please. Kind regards Simpo.by the way I am new to this forum and not sure if I am using it right. Apologies in advance.

[ITSv40]

Welcome to the forum. You need to post in the S40/V50/C30/C70 section of the forum as this only deals with the classic S/V40 upto 2004. Completely different cars.