Sam Hill

Hello Everyone. I'm hoping someone can give me input about an issue I'm having.

The car is a 2002 TT Quattro Roadster 6 speed manual.

The issue is that if I turn on the AC with the "econ" (air from outside) feature active, engine temp begins to rise above its usual position at the halfway mark on the gauge.

I'm assuming this overheat also causes my fuel pressure to drop because when the needle rises I also hear the fuel pump begin to make It's irritating high pitched hum from just behind the passengers seat.

As soon as i toggle the "econ" button off, the temp gauge slowly returns to normal. The fuel pump isn't as forgiving, but it stops whining after the car has cooled off for a few hours.

I learned about this issue when I tried to make a rushed 2.5 hour trip with "econ" active. the car overheated to the point of stalling and not running until it cooled down for a good while. I had it towed home thinking I had to put a new fuel pump in, but the next morning it started right up and still works fine as long as i keep the econ set to off when the AC is on.

Also, econ has no negative effect with heat on, only with the climate control set on the low side.

Thanks in advance!

Walpole5

I would suspect your radiator fan is not working properly. With the AC on, the fan comes on automatically, keeping things cool. I've only had my TT for a few months, so not an expert on the car, but I would check the fan temp. sensor first.

J. Patterson

Either your fan control module or the radiator temp sender for the cooling fans is bad. The AC Econ switch turns off the AC compressor. Since fans run all the time when AC is on ( Econ off) this is hiding the fact that the fans are not coming on as they should to control temperature.