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Air Conditioner Advice

Fu Manchu

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So, when it's cool, the AC runs as expected. Cold air comes through, nice and crispy, fan on 1 does the job.

When the temp gets to around 30-32º somewhere, the AC starts getting warmer.
When it's proper hot outside 40º the AC is about coolish to ambient in temp and the fan goes on full.

When this started, a noise also started.
It's not really there at idle. With revs it is.
A whine a little like a distant super charger.

Ac does run an unusually high pressure (had it checked when we had the VE re-gased). Maybe a clogged receiver/drier? Gas is not low.

The problem and noise isn't so bad with the AC off.

The car will also run sluggish and use a lot of fuel when this is happening.

Yesterday was about 40º and AC was hardly working again. It cooled off a bit with the seabreeze and turned the fan to 1 and air gets cooler. So time to do something.

Something bugs me about the cause being directly to do with the AC.
No squeaks. Just a whine.

Now if you pop the bonnet, it's not going to be easy to listen to the accessories and get the sound. Get some load on things with driving and you'll hear the whine. (Not the passengers)

So I've had an issue with starting difficulty and had a bad battery diagnosed. Things have been going ok since. It hasn't been too hot though. Car has been running great. Low fuel use, then the heat and bam, fuel up, power low, ac warm-ish, whine starts.

So in view of how the AC works (I get the basics, not the detail), I'm putting load on the electrics with full fan, compressor working harder, radio on, car accelerating, air goes ambient-ish.
Have I got a slowly dying alternator?

I did notice a smell after I parked the car, it smelt like a road works kind of smell, but I don't think there was road works (bitumen) going on near by and it was localised around the car. I dismissed it after hyperventilating while smelling around the house for the smell. It went away.

With load, would the ECM being cutting out the AC as voltage gets low?
Faulty alternator when it's hot?
AC clutch slipping with low voltage?
Would the AC put enough load on the alternator to really work it that hard?
What your ideas?
 
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Fu Manchu

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Sort of sounds like this.

and

That last one was the alternator. After he replaced the alternator the AC worked again.

Oh the belt is low k's, and is wearing on one edge.
 

lmoengnr

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Are the compressors a rotary piston pump type?
You stated the pressure was unusually high.
Experience with hydraulic pumps of that type, were the pressure increased just before they failed...
Maybe time for a new pump?
 

Fu Manchu

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It's been going on for 2 years or so. One battery down. Happened instantly one a really hot day.
Hasn't changed much. Same symptoms.

The aircon guy thought it odd for the pressure to be so high. Just said, filter/drier must be clogged.
 

Fu Manchu

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So when the ambient temp increases, does the compressor work harder or is it all the same as cooler days? (27-30º)
 
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