451 Climate Control Faults
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451 Climate Control Faults
The new fortwo has a more sophisticated climate control rather than the air conditioning in the 450 and Roadster. More to go wrong.
The new fortwo has a more sophisticated climate control rather than the air conditioning in the 450 and Roadster. More to go wrong.
Mechanically there is no difference, the difference is in how it is all controlled through the hardware.
With AC (air conditioning), if you set it on cold, it will blow out cold even if the air temperature in the cabin is lower than the air being blown out of the system. In which case the system is actually blowing out warm air as it'll be warming up the cabin.
With CC (climate control), the hardware monitors the temperature of the cabin which allows you to set a particular temperature. The system turns on and off to regulate the set temperature.
When you first start the car, it will only blow out cold air unless you have the diesel
fortwo with the electric heater. The car has to be up to full operating temperature
(4 or 5 blocks) before you can test the system properly. This is because the heater
uses water that is heated by the engine, if the engine is cold, so is the water.
If you have a 2009 or newer fortwo 451 then you have been fobbed off with the dumbed
down speedo (originally designed for the American 451) which doesn't even show this
important data. All you can do is moan and go for a 10 minute drive.
Fuse Fault
Do your windscreen squirters work or can you hear the pump when you pull the wiper stalk?
If not, you'll need to check
It is fuse 20 that powers the climate control hardware.
Controller Fault
If that's OK then the fault will probably lie with the heat controller (shown below).
It is the section with the rotary selector and the buttons along the top.
The black dot at the bottom of the rotary selector is the cabin heat sensor.
As yet we are unsure as to what fails on this unit but smart have been known to change
these for free and have probably since worked out the fault and updated the unit.
Climate Control Only Produces Cold Air
Thermostatic Valve
Cold air could mean that the thermostatic valve in the engine is stuck closed.
What happens is the engine circulates water just around itself until it reaches a
certain temperature, the thermostatic valve then opens which allows the engine to
pump the hot water through the cabin and through the front mounted radiator. If the
valve is stuck, the hot water is never circulated into the cabin.
The best way to see if hot water is getting to the front mounted radiator is to touch the pipes
going into it. Access is a bit fiddly but it is possible, maybe even through the front service panel.
Extreme Cold Weather
If it is extremely cold, the engine may have trouble getting up to temperature or keeping
temperature if the radiator is doing too good a job at cooling. If this is the case you may need
to create what is known as a winter grill which will be covered on the site in due course.
Controller Fault
If neither of those then the fault will probably lie with the heat controller (shown below).
It is the section with the rotary selector and the buttons along the top.
The black dot at the bottom of the rotary selector is the cabin heat sensor.
As yet we are unsure as to what fails on this unit but smart have been known to change
these for free and have probably since worked out the fault and updated the unit.
Climate Control Won't Produce Cold Air
You will probably find that the air conditioning gas has leaked from the system.
Get the system pressure tested and dye tested. If you don't use the air conditioning regularly,
the oil in the system won't lubricate the seals, they perish and the gas escapes.
Climate Control Won't Produce Hot Air
This would normally indicate that the thermostatic valve in the engine isn't fully opening
or stuck halfway open so the fully flow of hot water isn't making it into the cabin.
I wrote this on the spur of the moment so if you think of anything else, let me know.
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