Heater Control Valve
 

It's been leaking almost all the time I've owned the car (around eight years) so as it's been much worse in recent months, and with possibly some warmer weather on the way I'm hoping to be able to get it fixed. I at last managed to contort myself enough to get a picture and part number, and did a search on Ebay. There are several which look to be the same, but one or two, also apparently compatible (for 1992 Torslanda) which look quite different, e.g. this - 391962271529. The other type (as 282888587846) comes in a confusing range of prices so I'm not sure which to get. Does the first type incorporate a thermostat, for example? It looks as if it might, and it also looks to be more substantial.

Any advice gratefully received, please.

As far as I know, all are interchangeable. The two kinds require different angled hoses, as obvious in the pictures. I don't know, but I assume the cable angle/attachment is the same, or at least easily adjusted.

The first picture does have a thermostat, which I am coming to think I need to fit on mine, which has the second type. Not having a thermostat is useless - mine basically has only an on/off. It's either full on, or off. Even the tiniest movement of the lever turns it fully on.

Also the second kind are flimsy plastic and notoriously prone to leaking.

If I do swap to the earlier thermostat kind, I'm unsure where the sensor coil should go. Commonsense says you need it in the footwell, but an earlier car of mine had it poking inside the heater duct. That doesn't seem to me to be controlling the actual interior air temperature, unless there is some subtlety I don't understand.

I'm resurrecting this thread because I'm hoping to get the valve replaced soon. I bought the metal type valve and the mechanic had a brief look at the set-up and couldn't immediately see how it could replace the existing valve - how, for example is it fixed to the bulkhead?. Has anyone carried out this replacement? If so any advice or information would be really welcome.

Clifford, the mechanic asked the same question about the thermostat. My thought is that it should be in the footwell, but I imagine that even if it's in the duct it would still control the temperature, and the desired temperature set by the control lever in the usual way. At present I have the same problem as you, it's either on or off, I haven't even dared to risk moving the lever too far for fear of roasting to a crisp! I have the added inconvenience that whenever I use the heater some coolant is lost and ends up soaking the carpet, so something really needs to be done before the autumn.

From memory the plastic one isn't really fixed at all - it just sort of floats, held by the outer cable, the semi-rigid inner cable, and the two hoses?

But probably the metal kind needs a more substantial bracket. If I become inspired by your efforts and get round to doing this job I'm sure I could fabricate some kind of bracket, if necessary drilling holes in the bulkhead and using self-tapping screws. It's so long ago I had one on a car that I can't remember how it was fixed, but I do have two removed from previous cars and the thermostats appear to work. They might leak of course!

I did a replacement in about 2007, so can’t remember huge amounts, but the metal type with the thermostat are the original type and the thermostat did go into the heating ducting, not the footwell. I think they are no longer available, and wasn’t even then, my replacement came from a spares car I had. They were replaced by the plastic ones if you needed to buy a new part from Volvo. I’m afraid that’s as much as I can remember.

I don't understand that. The air in the duct is the first thing to warm up - that doesn't mean your feet are warm. It would be like mounting your room thermostat just above the radiator.

That is very true Clifford.

I think the idea must be to determine and stabilise a temperature of air being blown in to the vehicle interior.

Then the driver can choose whether to decrease or increase the temperature of the air coming from the heater to suit the temperatures &c. that prevail inside the vehicle.


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Yes quite true, the temperature setting isn’t what you want the inside temperature of the car to be it’s how hot you want the air that is being blow. You have to determine if you want the inside temperature of the car hotter or cooler and adjust the blower temperature accordingly.

I remember changing these now and again a long time ago , they have one or two self tapping screws holding them to a bracket and the sensing probe goes through a slot into the heater casing .. Easier to do with the glove box out ! There are several alternatives around if you cannot get the correct one , have you tried your dealer who can get a lot of vital 240 parts from the volvo classic warehouse in Sweden .

how about this :

https://www.carbuildersolutions.com/...s-heater-valve

or this :

https://www.carbuildersolutions.com/...n-heater-valve

That's not using the thermostat at all, just turning the heat up or down as required. Any progressive tap would do that.

The point of a thermostat is you set the temperature of the room or cabin at the temperature you want and the thermostat turns the heat source up or down to maintain it.