View Full Version : Why does my compressor decide to randomly turn itself on?


ChrisWB
03-16-1999, 12:03 PM
Throughout this whole winter in CT, I have had no reason to turn the compresor on. If you only need heat, why bother to turn it on? You can totally hear and feel the drain on the whole system.<p>Once in a while, like this morning, after I turned my car on I notice the compressor is on also. I know I didn't have it on before.<p>What da diley yo? (What's the deal?)<p>ChrisWB<br>99 1.8tqm<br>

Andy Hedin
03-16-1999, 12:29 PM
Totally normal operation for the climate control system in the A4. At some point in time you did hit the "Auto" button, which under normal operating conditions (temps above 35 degrees or so [check archives for the exact temperature cutoff]) would turn on the A/C compressor. Chances are, the outside temps in your area have been below that temperature for a while now and the first day above 35 (today), the compressor "magically" comes on.<p>Ways to avoid this:<br>1) Don't use the "Auto" button. Adjust temp, fan speed, air output manually. <br>2) If compressor does come on when you don't want it on, just hit the "*" [snowflake] button to turn off the compressor.<p>Andy Hedin<br>'97 A4 1.8Tqms, Wett 1.0 Bar Chip, ABT Filter, Euro Headlights...

Drew S.
03-16-1999, 12:30 PM
If you are trying to defog the inside of your windows, having the AC turned on helps immensely. What you need to realize is that just because the compressor is on, doesn't mean that it has to blow cold air. What you can do is use the AC to dehumidify the air and defog the windshield quickly.<br>

Drew S.
03-16-1999, 12:30 PM
If you are trying to defog the inside of your windows, having the AC turned on helps immensely. What you need to realize is that just because the compressor is on, doesn't mean that it has to blow cold air. What you can do is use the AC to dehumidify the air and defog the windshield quickly.<br>

tp
03-16-1999, 12:33 PM
if someone already said this, sorry, but in addition the compressor will also shut off under full power in order to focus energy on accelleration, then turn on once gas pedal is let up. great idea, but not something Audi thought of first.

Larry Victor
03-16-1999, 03:04 PM
Unfortunately, it appears as though the compressor CAN'T be turned on when the temp is below that mysterious number. I would love to be able to activate it when add'l dehumidification would help defog the windshield. Is this correct? I'd welcome a solution.

HVAC envy
03-16-1999, 07:19 PM

ChrisWB
03-17-1999, 06:25 AM
This morning in CT it was way warmer than yesterday (like 45-50 degrees outside). Compressor did not come on automatically.<p>It just seems ridiculous that it would turn on even in cold or even mild temps. The only time I see a need for the compressor (except to remove humidity of course), is when you want air cooler than the outside temp blowing in. In that case, the compressor should automatically come on in "auto mode" when the outside temp is above the setting on the climate control.<br>

JonC
03-17-1999, 07:06 AM
the refrigerant contains a lubricant for seals. It is good practice to run the AC for about 10 mins. every week or two in the winter to circulate the lubricant and keep seals from drying out.

Cathleen
03-17-1999, 07:16 AM
You had to manually turn on the A/C on my Honda Civic sedan. No one ever told me that I should turn it on periodically during the winter when it was above freezing. One spring my A/C compressor died and had to be replaced. The Honda dealer tells me that I should have turned it on at least once a week in the winter because if you don't keep it running now and then it will break down. The car was only 2 years old at that time.<br>So IMO Audi is smart to make the A4 compressor come on automatically now and then to save this potential problem from occuring.<br>-C.

Andy Hedin
03-17-1999, 09:33 AM
The compressor won't just automatically come on...you've got to either press the "Auto" button or the "*" [snowflake] button. What I'm trying to say is the system is smart and remembers what you've pressed....it will remember for a <b>long</b> time. Maybe an example will help illustrate my point:<p>Monday: outside temp is 50 degrees when you press the "Auto" button. Compressor comes on and you see the "snowflake" light up in the display. Turn car off ("Auto" mode is still engaged).<p>Tuesday: Cold snap hit last night, temps now below 32....climate control shows no snowflake symbol.<p>Weds: Temps back up in the 50's when you start your car up in the morning. After a moment you notice that the compressor has come back on and your climate control now displays the snowflake symbol again. You actually never left "Auto" mode.<p>I do agree that it seems ridiculous to run the A/C on a dry, cool day (temps in the 50's, low 60's). On days like that, I turn the compressor off. I will run the compressor if it's very humid out, like during a rainstorm.<p>I have no idea why Audi felt it was necessary to run the A/C compressor so much (other than keeping the internal seals lubricated).<p>Andy Hedin<br>'97 A4 1.8Tqms, Wett 1.0 Bar, ABT Filter, Euro Headlights, more...