QuestionQUESTION: My w124 mercedes aircon cut off during hot weather, but during cold weather( as in not so hot), it works fine. The cut off as in the compressor is not engaging so I am wondering what could be the problem. Also when it cuts off, it emits a foul kind of smell. Just like when I start the car and turn on the A/C, it has a bit of the foul smell and then is ok.. but as soon as the weather is so hot;is no cold anymore, but there is fan.
my climate control units has 3 button in the middle and 2 temperature selectors.
ANSWER: Timothy,
I would locate an independent AC service center and have them place the system on their diagnostic unit. It sounds like you have low freon. Then freon is low your evaporator in the car collects frost from the humidity and that block airflow over the unit.
This excess ice melts and causes flooding of the collection tray. If the exit tube is clogged to the outside of the vehicle then you could have mold and mildew form in the tray. The wet environment can cause odor.
Good Luck
Rob
---------- FOLLOW-UP ----------
QUESTION: Actuallly I did a recharge the A/C, so it should be no problem. When I went to the Auto electrician, they told me is the compressor and the climate control unit. It cost me heap to change both of these and I skeptical about their opinion. So I went to another auto electrian and they told me is the fan unit.
I am just wondering whether the A/C temperature swtich need to replace. It could be something this simple.
ANSWER: Tim,
You say recharge. Was this done using a service machine that vacuums the system and returns the correct amount of freon, or did you add freon yourself?
Rob
---------- FOLLOW-UP ----------
QUESTION: No it was done using a machine by a reputable mechanic that I know very well. However the mechanic told me it was some sort of electrical problem and can't help to remedy the problem. I done the recharge/top up gas about 6 months ago and it was great. So now my A/c has problem that I stated above.
I am just guessing whether the A/C temperature switch got to do with this problem..
Now the problem even happens during the night.. When i drive the car about 10 minutes, the compressor cut off. So in order to have the compressor to cut in; I have to switch off the car and turn it on again..
AnswerThe AC compressor clutch is controlled by a thermocouple switch at the evaporator. It also has low side and high side freon pressure switches in the system. Low freon shuts off the compressor to avoid damage because the lubricant travels with the freon. The high pressure switch disengages the compressor clutch to keep from damaging the compressor seals or blowing out a line.
There must be a certain amount of space for the freon to expand and contract for the system to operate properly.
If you are satisfied that the freon level is not too low or too high then there may be an air restriction in the evaporator.
If the evaporator is freezing over then the thermocouple will switch off the compressor until the ice melts. The evaporator must have sufficient airflow through the vein to keep the moisture from collecting there.
If the intake filter is dirty then the moisture from the passing air condenses on the fins and freezes. Your odor indicates that there is some debris in the evaporator or its pan.
