QuestionQUESTION: My '98 A4 has issues with the AC. Just recharged it yesterday but it's blowing warm air. Compressor doesn't seem to kick in, as there is no additional noise, which was the case when the a/c was working fine previously. On a side note, my engine gauge shows the engine overheating with a warning sign even when starting from cold. An ECT replacement might be due. Will the high engine temperature indicator prevent the compressor from kicking in by any chance?
Please help!
ANSWER: Hi Ranja,
I doubt the temperature indicator is directly responsible for the AC not working, Start off with the AC console, check if the 'Econ' light goes off when pressed,if not then that means that the AC compressor clutch is not engaging, a fact that can be verified by looking at the compressor and having some body press the switch a couple of times, the Middle part should engage when the econ light goes out. if it doesnt then there could be a couple of possibilities,
Either the wiring to the AC clutch itself is faulty(or the wiring is ok and the clutch is faulty), the external temperature sensor (located infront of the radiator viewed with bonnet open between bumper and radiator) is fautly, or one pressure switch in the AC lines is faulty or also there isnt enough pressure in the lines to activate the above pressure sensor.
Before spending any money make sure that the knob that controls the temperature in the cabin turns all the way end to end freely, it could be stuck in the 'hot' position.
As for the temperature indicator (for the engine) disconnect the sensor and see if the warning disappears, if it does then the sensor it self is faulty, if it doesnt then there is a short to ground some where along the line, find and rectify it as necessary.
---------- FOLLOW-UP ----------
QUESTION: Thanks very much for the fast reply. A few more questions by this newbie who knows as much about cars as politicians know about speaking the truth.
Where is the 'Econ' light? On the display unit, I lower the temp all the way to low and then press the button next to it with a * image on it. This is when the ac should kick in. It stays on throughout.
I will check if the compressor clutch is engaging...where is the compressor located? I will also check the outside temp sensor.
Lastly, where can I find the engine temp sensor?
Sorry for the newbie questions...thanks in advance.
AnswerHey dont worry about it, we all got to start somewhere right??
The button that you describe should be the econ light, if it doesnt go off then there is fault some where in the system, the AC compressor is located on the engine and it driven by the engine via a fan belt, it should be on the front side between the radiator and engine it self, depending on the engine type.
As for the temperature sensor it is loctated on the coolant circuit, but the exact location depends on the engine type as well. follow the pipes coming out of the coolant radiator and you should find it mounted on the engine usually on a plastic flange. it is either black or green and had four pins.
also try going through Audi forums on the web, there is a wealth of information available from other Audi owners and you might even find another Experienced audi owner near you who can help you learn the ropes.
