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Major Vibration at Idle W/ A/C or Heat On

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9K views 16 replies 6 participants last post by  Fierceintent  
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#1 ·
I drive an '03 ZX3 with the zetec-e motor and 4F27E ATX. If I come to a stop when in drive, or neutral, while I have the A/C or Heat on any fan setting higher than 0, there will be lots of vibration throughout the car, interior and exterior. I have already replaced the rear (dog bone) motor mount and plan on doing both the passenger and driver side mounts this week. I believe the A/C compressor clutch is going out and plan on replacing the whole compressor soon. Now, I've noticed in my Hayne's repair manual that the heating and A/C electrical systems are connected. Does this sound like the compressor is affecting the heating system or that there is another fault in the electrical system? Has anyone else experienced this problem?
 
#4 ·
Heat & A/C connect in that the A/C also comes on when any defrost position is selected. Fan also needs to be on for the A/C to work, it shuts off when the fan is off.

Extra load from that system could increase vibration, I would want to also check if the idle speed drops with the A/C operating (could be another issue).

Passenger side motor mount IS a suspect for added vibrations, particularly at idle. Ford replacement is the one you'll see recommended to actually last and reduce vibration for that particular location (mail order sources for less expensive ones).

A quick check to confirm the mount as an issue is to SLIGHTLY jack the engine with a board under the pan to take the weight off the mount a bit. If the vibes are dramatically reduced that way, you've confirmed the poor mount.

A/C clutch may be a separate question, what symptoms make you think it's going out?
 
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#6 ·
The tach drops to about 400-500rpm when I'm idling with heat or A/C on any speed or direction setting. I've watched the compressor when I have the a/c on, while in park, and it'll spin, the rpms drop, then the compressor will stop spinning, the rpms will jump to like 1500 for a little bit, drop back down to about 1000 and stay there, and it'll stop spinning periodically. I believe when it stops spinning, the fans will kick on and once they're on, it'll start again. When it is spinning, it almost looks like one of the bolts or something is loose because you can see space between the plate (?) On the outer edge of the pulley and the rest of the pulley. It's hard to explain.

Sent from my SM-G920V using Tapatalk
 
#5 ·
I say the same thing. Your IAC could probably use a cleaning- it's easy to clean, but difficult to get to since it's on the bottom of the intake manifold. It sounds like it isn't boosting the idle like it should with the AC on, and that's what's causing your vibration. A bad motor mount would only exacerbate the vibration.

When an AC clutch goes out, it will either not work at all, or it will lock up and screech the belt. You don't have those problems.
 
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#9 ·
Change the pass side mount and don't use one from a parts store, they do the same. Even normal a/c working shakes these when the a/c is on, it drags rpm down just enough to enter the vibration zone and so do the fans at the moment they kick on. The extra electrical load does it. The IAC is supposed to make up for it but doesn't quite on older engines. They really need a software update for older engines that addresses that by bumping the compensation of the IAC up more.

Ford only on the mount, you like most others will likely regret not doing so, the aftermarket parts often don't fix the issue at all or if they do break again in a month or so.
 
#10 ·
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