OK, I have owned a 1990 240 DL Sedan for over 1 year now. It is a Canadian model with no A/C. It has a mechanical type cold/hot slide switch. The problem is, every time I take it a millimeter from the cold setting (far Left) to just a tad to the right, I get blown with extreme hot air. AND, that is with the fan setting OFF !. I am new to this model, and I think I read somewhere there is a module above the gas pedal that regulates this mechanical temperature setting from cold to hot. I would like to know if that is true and what part I need to correct this problem. And, yes, the blower works great in all settings as well as the floor button when depressed. Also, while I am on this subject of heating/fresh air, when do I use the Circulation button? I believe the owner's manual mentions this, but I don't remember why I would use it in a non-a/c car. Thanks in advance.

 

I wanted to clarify something. When I toggle the slide from all the way cold to just a little to the right., in a matter of minutes, I can feel a lot of heat emanating from the vents on the dash. This is with the fan in the off position. I can't seem to regulate the amount of heat on the slide. It is either outside temperature air OR Very hot air from the heater core. No way to just get (a little) heat. Just cold or very hot. No in between .

 

If you will take the left side panel off the side of the console - you will find the heater control valve. When you slide the lever a cable opens a simple water valve with a rubber seal that shuts off the flow of water. The valves don't really have a fine adjustment. And when old they don't turn all the way off sometimes. It's certainly possible that a new heater valve might have a more flexible rubber washer that might be less sensitive - but I doubt it. All newer Volvos use a blend door to mix heated and fresh or cooled air. Temperatures are much easier regulated with that style system - but that's not possible with a 240.

You would use the Recirculate button - if you wanted to try to prevent something like bad diesel exhaust from entering the car. It's not to be used when humid - for it will trap the humid air in the car and fog the windows.

 

The problem is not turning off the heat setting at all. It's 20 degrees out right now. If I get the car to operating temperature AND leave the slide to full cold setting, I will get 20 degrees of air coning through the console vents. AND, if I move the slide over to the right ( just a tad), it will get so hot, you can't bear it for very long as it's FULL HOT. So, my problem doesn't concern me during the summer because I get fresh outside air without any heat when set to full cold. But during the winter, it is unbearable to move over to a hotter setting for very long before it becomes too uncomfortable. Does that clarify your answer? I'm willing to test or replace any item that is controlling the mechanical regulation of my physical action of moving that wire cable slide from (OFF- far left), to the full closed setting. But to get at least a little bit of regulation of the hot air when I move it towards the right into the red zone, it just simply gets red-hot with no in between.

 

As for the re-circulating button and your answer. I would have to say that I would never have to use that button at all. Because I have no a/c. And if I need fresh air above 75 or 80 degrees in the summer, I would open all the windows for relief. So, I would have to breathe diesel fumes if I wanted to not sweat to death with the windows up. I would just use another A/C car I own at this point.

 

E-euro parts has a complete kit for $40 US. I ordered it as a safeguard to fixing it in the future if my existing parts can't be repaired to work properly.

 

The symptoms you describe are due to a bad heater control valve. The original heater control valves were rather complex and if I remember correctly had some sort of thermostatic control that goes bad over time. In my 240s I bought a simple generic heater control valve and rigged up a cable to the slide mechanism to get it all to work. I documented on a post in Brickboard but I don't see it there anymore. I looked at the EEuroparts valve and it looks to do exactly what I did. Give it a try. Not sure the quality of the valve they use (it looks pretty cheap to me).

 

Act1292 has a good point - perhaps the thermostatic bulb is bad and that is not allowing finer regulation of hot water flow - I've replaced many heater valves - always for failure to shut off - but have not seen the thermostatic bulb fail (but those valves are much older now than the last time I replaced one)

 

Thanks ACT1292 and hoonk for your responses. I believe that could be the problem. I really am just getting tired of constantly shutting off and turning on the mechanical slide when driving long distances. It could be worse: it's not leaking, I still get heat, AND I can shut the heat completely off if I want fresh, outside air. But I will get to the heater control valve and see what's happening (or not). With the kit I ordered, I get all replacement parts at a good price. I could replace the unit with the kit I ordered from eEuroparts https://eeuroparts.com/product/profe...weden/87431998 as it contains: (1) Heater Control Valve (2) Heater Hoses (1) Hose Clip (1) Control Cable (1) Mounting Bracket (1) Insulation. And see if it fixes the problem And I can keep the original parts as they somewhat work. As far as the cheap parts comment, this company says Proparts is their best aftermarket parts provider (other than OEM0, and they are in Sweden. Either way, this is a part I literally use only 4 months out of the year when it is real cold, and I need to (blend) the outside air with heat from the heater core. Another (cheap) fix may be to install a ball valve on the intake heater hose on the engine side and partially close it during the winter in an attempt to regulate the heat. Also, by doing this, in the summer I can completely close off the circulation of antifreeze into the heater core as a preventative measure should the core decide to leak inside my car. Remember, I have a non-A/C car, so that is that.