Can anyone tell me what the idle up switch does as i havent got a clue i have had my townace for 2 years but i have only had the intrernet for two months and found this web site - (#2572) John Heaps, 28 Mar 02

Self explanatory, really- it raises the tickover speed. Only works if the blower is turned on, though, as it's intended to warm the car up quicker in cold conditions. - (#2573) David Miller, 28 Mar 02

It also works via hot/cold box if you have one.
When you switch to hot it raises the tickover.
You can check the device for this on the top towards the back of the diesel pump near the throttle linkage. It looks like a diaphram type device. Hope this helps. Phil - (#2576) Phil Cook, 28 Mar 02

Or if you turn on any of the Air Con systems it will put the tick over up. When engine is warm & at normal tickover, try flicking the switch, if it doesn't put the tickover up, try turning on the Air Con, then check that the air con compressor is now turning, if it is the tickover should go up a little, if it doesn't then you have a problem. To increase the idle, the air con switch operates a small valve immediately under the passenger seat, the idle up switch operates another alongside, they then allow a vacuum from the servo to pull on the diaphragm unit on the throttle housing, thus raising the revs, you can see the diaphragm unit move when either switch is pressed, if it doesn't move, the most likely cause is a detatched vacuum pipe, this tends to be the one next to the oil filler cap, which if going nowhere has come away from the vacuum unit under the air filter hose, look for the little spiggot of rubber pipe sticking out & re insert it, this should restore the vacuum & thus make the system work. If it isn't vacuum related then it is probably one or both of the solenoid operated valves not working. PS check the fan switch is on, as it powers up all of this system. HTH Regards Rob. - (#2577) Rob Drinkwater, 28 Mar 02

There have been a few follow ups that have said what the idle-up switch does, but not why it does it. Simply, the air conditioning pump is belt driven by the engine. When you turn the aircon on, it puts an additional load upon the engine which means that the engine has to work harder. The speed of the engine therefore drops, which can be a problem if you put any additional loads upon the engine (such as rear demister or power steering which both derive their power from the two other drivebelts). The switch is therefore supplied to prevent stalling a cold engine, or to bring the idle speed up to a comfortable sounding hum, rather than a slow uneven judder. - (#2631) Barrie Kulik, 2 Apr 02

Another point no-one's mentioned is that when cruising gently, say 30-40mph, with the aircon on you can sometimes feel the accelerator pedal drop disconcertingly away from your foot slightly as the a/c compressor cuts in, and with it the a/c "idle-up" function.
This has nothing to do with the idle-up switch on the dashboard which, as I understand it, is there only for if you want to get more heat in cold weather when the engine is idling (as I was in a 3-hour traffic jam at Calais last Saturday evening).
You should not need to use the idle-up switch on the dash in for the a/c unless the a/c's own idle-up system has failed. - (#2674) Dave Mason, 8 Apr 02

Correct, Dave. Same actuator, different solenoid valve - (#2677) david miller, 8 Apr 02

Could anybody please let me know what the "Idle Up Switch" is used for? Many thanks

- (#6903) Jo, 24 Jan 03

increases the idle speed to make the heater work better. only works if the fan is on tho.

- (#6904) david miller, 25 Jan 03