Heater problem

[NGHaydon4]

I have suddenly developed a problem on my 440i with the heater. It has stopped working in that it will not blow out hot air plus the air blower does not appear to be working at full force. The engine temp is also slightly higher than normal and the electric engine fan appears to cut in more frerquently. Thought it might be Thermostat? Any ideas/experience please? Thanks

[leeleefocus]

Not familiar with the heater on that car so cannot help with the speed of the fan but the lack of hot air could be down to a blocked heater matrix or faulty thermostat.

Are the hoses hot where they go into the bulk head. If they feel cooler than the other hoses once the car is up to temp then i would say its probably a blocked matrix.

[terrywilde07]

it;s quite possible it could be a dodgy thermostat... feel the top and bottom hoses on the Radiator.. they should be the same temperature, if there's a big difference in temprature between the two the 'stat needs swapping... go for a 'Gates' thermaostat, they're the best in my opinion.

The heater might not be blowing hot because the heater control valve has had its day... or the water level might be LOW... the water will always circulate around the engine if it is too low, a higher engine temperature does point to a lack of coolant... possibly down to an air lock if the header tank is full... to bleed the system there is a screw in the top of one of the rubber water hoses on the right hand side of the engine (see pic), simply undo this and any air that might be in the water jacket will be released, check header tank and top up if neccessary, oh it's winter so the key word is 'anti-freeze'.

not sure on why the blower fan is giving you problems... best check the air intake duct to see if there's an obstruction, leaves or something, on the pollent filter if it's got one. the fan will blow 100 cfm on low speeds but when you put it on speed 3 or 4 the possible blockage will still only allow 100 cfm through instead of 150 cfm... worth checking though

[terrywilde07]

here's the location of the coolant bleed screw in the top of the hose

volvo 460 GLEi 050.jpg

[B20F]

it;s quite possible it could be a dodgy thermostat... feel the top and bottom hoses on the Radiator.. they should be the same temperature, if there's a big difference in temprature between the two the 'stat needs swapping...

If the thermostat is working hot coolant runs through the rad too cool down, so there hould be a difference in temp between top and bottom hose. If the thermostat is dodgy it stays open and coolant is running through the rad no matter warm or cold. This would mean the coolant can't get to normal operating temp and the heater can only become luke warm.

The heater might not be blowing hot because the heater control valve has had its day...

The 400 series don't have a heater control valve. Coolant is constantly running through the heater matrix if the engine is running. An air flap controls the hot/cold flow to the interior. You can check the cable running from the dash regulator to the flap on top of the heatermatrix. If the cable became disattached or loosened you can't close the airvalve so only cold air can comes out.