is it normal to feel a drop in power when i switch on the a/c in my fiesta? is there any way of stopping this like putting in a bigger battery?
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Is it normal? Don't know about the Fiesta specifically, but if you have a small engined car, it's perfectly possible for the air conditioning to draw enough power from the engine to make a noticeable difference.
The battery gets its power from the alternator, which is driven by the engine... basically, a bigger battery won't make any difference at all. (In fact, as the battery is only there to provide electrical power when the engine is off, it's not a battery issue at all). There may be a fault in your air con that is causing the compressor to take too much power, but if there is not, there is not much you can do.
(I assume you have the 1.25 engine - Blue, if you are not too busy burning around in your new 1.4, let us know your experience of a/c with that engine).
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>>I assume you have the 1.25 engine
No i have a 1.4 i Ghia Fiesta. I do notice however that in th corolla my wife drives there is a slight drop in power also.
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Yes, it's normal. The a/c compressor pump is powered by the engine via a belt, not the battery, so don't waste your money replacing it with a bigger one. Even on my 2.2 litre, 147bph Vectra I can feel the drop in power with the a/c switched on.
Mate of mine that used to work for a Saab main Dealer said that during the summer months customers would phone up to book their cars in for a service as the engine was feeling flat and lacking in power. Their first response was to tell the customer to turn off the a/c, and if there was no difference to call again to be booked in for a service. Very few people called back.
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I really don't understand that with bigger cars you can still get a drop in power. I have never noticed a drop in power in any of my Mercs from the C220 up to my current one so for a Vectra 2.2 to lose power with the A.C. is awfull.
I can understand it in a small engine like a fiesta as obviously the compressor will sap power but not enough to notice in a bigger engine.
Could it be that the Merc compressors are undersized or do some car manufacturers not work out the A.C. loading properly and install badly designed systems.
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so for a Vectra 2.2 to lose power with the A.C. is awful.
Marcos,
Don't get me wrong, it's only a marginal difference in power. There's still plenty available on tap from the loud pedal, you just have to press it down a little further to compensate for the compressor running. On a smaller engined car it can be significantly noticable.
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O.k. I thought you meant a big difference.
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For what it's worth I have always noticed a power difference with the a.c. on in an S reg Honda Accord 2.0l (150bhp?) and an X reg Merc E240 V6(170-ish bhp). In fact in the Merc I regularly turned it off when I needed to do a 'quick' overtaking manouever. It wasn't a drastic drop in power but enough to make a difference.
In fact the current car, Omega 3.0 (204-ish bhp) is the only one I've had with a.c. that I can't tell whether it's on or off (apart from feeling colder that is).
PST
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The compressor takes about 8bhp @ 300 rpm, so you can work out for yourself what effect it will have to driveability.
Most new cars now have variable displacement compressors that run continuously, so you don't get the 'all or nothing', on and off. Mercs, vauxhalls, VAG etc have ad them for some time now.
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So how do you tell which one you have fitted?
306 2.0 SE Cabriolet
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.>> So how do you tell which one you have fitted?306 2.0 SE Cabriolet
By the way they cut in. The instant clutch type come in with a clunk and a noticeable dip in the rev counter. For info the old 1.6 90bhp scenic did just that, "clunk dip every switch"
The variable type dont which i think i have on the new Laguna, it has two modes of aircon, economy and brass monkeys. Neither mode causes a clunk dip that i can tell.
Mind you opening the windows on the move causes a minimum 4% drop in fuel economy
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You don't get owt fer nowt. My Toyota 2.0 litre doesn't particularly drop noticeably in power but try this : Get on a straight fairly fast road and glance at your rev counter with a/c off. Then switch a/c on and see the power surge. That's what it's costing your engine (and fuel consumption) to power your a/c.
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Hi Conor,
the a/c in my 2000 Fiesta 1.25lx really cuts the cars power (like chucking an anchor overboard). In fact to such an extent I flick it off when negotiating junctions etc where decent acceleration is required for safety.
During normal running it can be felt cutting in and out but it doesn't bother me too much anymore, I've got used to it. I think really the engine is too small to cope with the extra burden of the a/c system smoothly.
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Conor,
oops, just read thread properly, I see you have a larger engine. Still if it's anY consolation I would guess mine is worse than yours and I have lived with it from new, drive it all day for work!
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Same here, I had the 1.25 and the A/C made a noticeable difference to the car's performance.
Just like Cosmo I could feel it cutting in and out as I drove, and I would switch it off if I needed to use the full power of the engine.
I would imagine that it won't be much different in the 1.4
Although, in my new Fiesta MK6 1.4 I have to say it is much less noticeable than on the 1.25, but it's still there...
Blue
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This thread will be moved across to Technical Matters later today.
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Although I agree with these feelings of power loss, it should be noted that if full throttle is applied the A/C will cut out for a set time of 12 seconds or so. There is no point in switching off the A/C yourself. Just use full throttle.
The cut in/cut out is most noticeable and was very bad on a Mondeo 2.5 that I once had. Big engine does not mean you don't feel it. There is a move now to use more sophisticated drives for the compressor which are not just on/off clutches.
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my 2.0 beetle looses power as well, not alot but enough that i notice it, you can see the revs drop slightly although i have not noticed any problems with performance.
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My Primera 1.6 is similarly affected when driving gently. The worse time is when the air con clicks on/off while you are changing gear - makes a right game of matching revs!
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I could feel the air con cut in on my Nissan Primera 1.6.
I now run a 2001 Ford Mondeo 1.8 and I've never noticed it.
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I have a 2001 1.6 Fiesta with aircon. Run it all the time. Only notice any change when the car has been left in the summer sun and I switch to coldest setting and highest fan speeds. I would imagine a 1.25 Fiesta would struggle a bit with aircon .. that's why I bought a 1.6.
My experience of older cars was power loss with aircon was quite severe (especialy US car rental 6 cylinder cars in the 1970s which pinked and were horrible ) but my Audi A4TDI saw no difference altho' fuel consumption was about 2mpg better in the winter when the aircon rarely switched on...In S Africa a Mercedes 260 coped happily with aircon at highest speeds and hottest days:-)
madf
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