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heater doesn't work[200/1986] posted by Maarten on
Wednesday, 26 August 1998, at 3:01 a.m.
The heater in my heater 240DL does work or doesn't. It either produces cold air or hot air (depending on the positins of the regulator swith in the dash). Once the switch is all the way to left it produces cold air. When I move it only a little to the right side it produces only hot air. There is nothing like warm or a little bit warm air.
I found (after removing the under dash panel) a mechanism that regulates the airtemp under the dash. Does anybody know how this thing works? Or waht is causing the problem? The cable is mounted properly and I can see things moving in the mechanism while adjusting the switch.
Thanks
-Maarten
Re: heater doesn't work[200/1986] posted by Don Foster on
Wednesday, 26 August 1998, at 8:26 a.m.
Maarten --
That valve is the temperature control valve, and has almost certainly failed. It's not uncommon for that valve.
It has a built-in temperature sensor that monitors the temperature of the air coming out of the heater. If it's low, the valve opens slightly; and if it's high, the valve closes slightly.
When you set the temperature knob on the dashboard, you're setting a desired temperature (called a setpoint) and the valve attempts to self-regulate the temperature to your setpoint. The valve opens or closes itself depending on the setpoint and actual temperature.
The newer 240s use a more simple gate valve in place of yours -- sort of like the faucet on a kitchen sink. When you adjust the dashboard knob, it simply opens or closes the valve directly. Volvo sells a retrofit kit for the earlier 240s to install this simple valve, and I've used one succesfully (on an '89). Of course, you can get an exact replacement valve instead. The downside is that the exact replacement valve will probably fail again in 8-10 years, whereas the gate valve is good forever (unless you physically break it).
--Wednesday, 26 August 1998, at 12:39 p.m.
Maarten,
Try replacing the heater control valve with the updated kit p/n 9131998.
It takes a little time to replace, but the new valve is a shutter valve and is easier to control.
Ted
Stillman Volvo
Re: heater control -cheap fix[200/1986] posted by Dave Stevens on
Thursday, 3 September 1998, at 4:52 p.m.
On the older style heater valves there is a little adjusting nut (on the temp compensator "saddle"). If your heater valve isn't totally shot, you can often extend the useful life by simply re-adjusting this.
You'll need to loosen the valve from its mount, but you don't need to open any hoses. Start by checking the cable adjustment so that the valve fully shuts off when the console control is fully off. Make sure there are no kinks in the temp sensor tube (game over) and it is fed well into the heater box. With the engine fully warmed up, the heat control set at mid-point and the fan on high, adjust the nut until "room temperature" air comes out the dash vents. You pretty much have to do this on a cool day.
Maybe I'm just lucky, but I've fixed 3 out of 3 on this one. Normal reaction is "Gee, that's better than original". I've had to re-adjust them again after 3-5 years. At any rate, certainly worth a try.