john.marje4u@my
10-05-2008, 08:48 PM
My 1995 C180 has an intermittent problem with its heater. I have it set to cold air (both sides) and vented to screen. occasionally, (getting more frequent), the cold air turns to hot - (I do not have air con) and both sides are either allowing cold or hot air in depending whether the fault exists.
When the car is in the shade ie: in garage, the rotary heater control switches that operate the blower and air direction, can be seen flashing with a regular pulse with the centre air recirculating switch only flashing momentarily each time it is operated and remaining inoperable. Normally, after about 20 minutes or so, the fault goes away and everything returns to normal, but recently the problem has remained for a whole day. If I switch on the side lights, everything seems to work OK but then the mileometer illumination flashes with an irregular pulse. I can remove fuse no.2 which controls the heater control panel and horn - this has the effect of illuminating the rotary switches and thus stopping them from flashing but the blower still works (I assume that the air would now become cold again if I waited long enough). I think the problem lies with the heater control unit ( I cant see it being a wiring short or similar) but I am no professional mechanic. Anybody have any suggestions please. The car has been with a local main dealer for 2 days without the fault appearing. The day after collection, the fault appeared again and remained until I pulled into the dealers forecourt when It promptly 'cured itself'.
When the car is in the shade ie: in garage, the rotary heater control switches that operate the blower and air direction, can be seen flashing with a regular pulse with the centre air recirculating switch only flashing momentarily each time it is operated and remaining inoperable. Normally, after about 20 minutes or so, the fault goes away and everything returns to normal, but recently the problem has remained for a whole day. If I switch on the side lights, everything seems to work OK but then the mileometer illumination flashes with an irregular pulse. I can remove fuse no.2 which controls the heater control panel and horn - this has the effect of illuminating the rotary switches and thus stopping them from flashing but the blower still works (I assume that the air would now become cold again if I waited long enough). I think the problem lies with the heater control unit ( I cant see it being a wiring short or similar) but I am no professional mechanic. Anybody have any suggestions please. The car has been with a local main dealer for 2 days without the fault appearing. The day after collection, the fault appeared again and remained until I pulled into the dealers forecourt when It promptly 'cured itself'.