Air Conditioner Making A Soft 'choo' Noise, Power Affected

[tridentt150v]

Hi all,

1998 Gts2.5t with mods, but the mods aren't the issue.

When driving my car and the a/c is on every 5 - 15 minutes [its random] there is a soft 'choo' sound and the car feels the same as if you hit a shallow puddle of water on the road - so a soft lurch like the motor misses a beat???

If I turn the a/c off the sound stops. I can drive 500km on a trip and with the a/c off and the sound never happens. But as soon as I use the a/c the choo and the slight miss happen. Both are soft, the choo is soft and low and you can sometimes not hear it [but you feel the car react and then realise you did hear the sound]. The miss/lurch of the car is soft, as I said it feels sort of like when you hit a shallow puddle of water on the road.

Here is the kicker......my shitbox Courier is doing the same thing but its a bit harder. No I haven't played with the a/c, the belts aren't slipping [different sound anyway], and the a/c compressor in the courier is newish.

I've had it to two different auto electricians and they have driven the vehicles and have experienced it. Neither business has ever seen it before and both are scratching their heads. A/c's work fine, pressures and all good, they say that the gauges and diagnostics are all fine and as good as you could want, they cannot explain the reason for the sound.

So I thought I'd ask the brains trust on SAU and see if anyone else has had this issue and what it is.

[kingtube69]

Never heard of the "soft choo" but the difference/lurch whatever you call it would be the compressor clutch engaging and disengaging to as it reaches desired temperature or tries to cool down to the desired temperature. It's normal for idle to drop a little or for you to feel it in the car when the compressor engages or disengages because its additional load on the engine..

As for the sound, nfi why it makes it.

Does it sound like its coming from any particular area?

[hardsteppa]

sounds perfectly normal to me? Aircon compressor kicking in/shutting off causes power change, more noticeable depending how shite it is (used to be like putting on the handbrake in my old celica) and the system gives a little pssh as pressure activated/released.

Also if you happen to be driving in the tropics and going 100k and the aircon is on and you start to see steam/smoke coming out thru the aircon vents it does not mean your car is on fire, just water vapour apparently from the change in humidity coming through the system too fast for it to disburse normally...or something similar, forget the exact reason....(but caused me some brief concern when driving back from Cairns, I tells you)

[tridentt150v]

Sorry guys but its not normal...........as I said two aircon businesses have heard it and felt the effects and they are stumped. But I'm in a small town and their exposure to plus the fact that they are both auto electrical businesses means that they have good experience but maybe not a wide experience.

If my vehicles were 1000cc 4 cylinder units then yeah the compressor cutting in and out would be very noticable, but they are bigger motors with good power, and the old days of turning the a/c off to drive up a hill or overtake are long gone. The courier is a v6 4.0 petrol manual, and my Skyline pumps out 300rwkw so I honestly can't see that happening. I drive [and have owned] other vehicles with aircon and the compressor cuts in and out and you hardly notice it, this is nothing like that.

[Ben C34]

Wierd.

I assume the guys that inspected it put a meter on the battery and checked what's happening with the voltage when the ac is engaged.

What ecu.?

[tridentt150v]

PFC for the Skyline, standard for the Courier. Might get them to put a meter on the battery and see if anything is dragging out big power. And you are right.........weird!!!!

[Ben C34]

Actually sounds like you have a voodoo curse.

[blind_elk]

I had something similar happen after I had the gas changed to a more modern gas. The solution was to have the a/c fan on permanently, rather than as a thermo fan.

[tridentt150v]

Thanks blind elk [aka noeyedeer lol], I might check that out and see.

[Kylie81]

lol, the choo sound seems to be weird

[tridentt150v]

Never ever cured it, just live with it, still happens.