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Old 07-12-2009, 07:52 PM   #1
Snowphun
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Question Air conditioning causes rough engine, ideas?

Recently I had a significant amount of work done on my MY02 WRX: engine was removed to resolve an issue with one of the heads, t belt and clutch were replaced. AS a result the AC system was opened, then recharged by the shop. Surprisingly I had only one issue as a result of the work: my AC does not work as it used to. With the AC on the engine feels much rougher at idle when the compressor engages. The revs don't appear to drop but I can feel much more harshness through the pedals, wheel and floor. Even when driving the engine feels rougher with the AC on, particularly noticable after lifting off the gas. In all situations the AC blows cold air.

So what could cause this? Would an incorrect (either high or low) amount of refrigerant pressure cause this? The AC belt was too tight for my liking when I got the car back, I loosened it with no real change.

Thanks.
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Old 07-12-2009, 08:26 PM   #2
munkis
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try loosing the motor mounts, starting the engine, turn the a/c on, rev it, turn it off and re-tighten the motor mounts.
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Old 07-13-2009, 01:39 PM   #3
Snowphun
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That's easy enough to try, though I would expect to have imbalance issues all the time if things were really out of line. This issue is only occuring when the AC is on.
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Old 07-13-2009, 07:34 PM   #4
Greg B.(blue 06 WRX)
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Possibilities:

Low Battery (Car off:11-12volts Car on:13+)
Bad Compressor?
Bad Idle Control Valve?

Good Luck.....
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Old 07-14-2009, 01:03 PM   #5
Snowphun
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Update: loosened the motor mounts, ran the car, shook the engine, no change in position nor the roughness. battery has expected voltage, idle is fine when the AC is off so I don't suspect the ICV. Compressor is kicking on and working.

The problems occurs at most engine speeds, not just idle. The AC system was opened, could having the incorrect amount of refrigerant cause something like this? Blows cold air.
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Old 07-14-2009, 02:21 PM   #6
CasperForester
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Maybe that the ac is going bad, spinning slower when on. Causing it to be rough
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Old 07-14-2009, 04:55 PM   #7
Snowphun
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Quote:
Originally Posted by CasperForester View Post
Maybe that the ac is going bad, spinning slower when on. Causing it to be rough
Yes, that appears to be true. The question is, what is causing the problem, what part is going bad? Or is it related to the system recharge? I've never dealt with AC issues.
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