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Old 05-27-2012, 02:27 PM   #1
BoostedMKIV
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Default I need help with an A/C problem....

Hey guys...

Here's the deal; I have a 2004 RS, with 120K miles on it, and the AC has worked great for a very long time...until I had the belts replaced and the harmonic balancer replaced.

Ever since then, the AC compressor makes this loud audible CLICK every few seconds while Im driving that can be heard across the street! Plus it feels like it's parasitic and makes the engine lose power every time it does it.

Upon first inquiry, everyone told me I was running low on refrigerant, and thats why the compressor was cycling over and over...SO, I bought some refrigerant and upon hooking it up to the AC port, realized my system has plenty of freon and the pressure is just fine. Air blows SUPER cold.

Can anyone PLEASE tell me why the compressor is still clacking super loud while I'm driving??? It's ONLY when I'm driving with the A/C ON...by the way.

Thanks!
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Old 05-27-2012, 04:03 PM   #2
Mulder
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Sounds like it's overcharged and the high-pressure cutout is tripping. Have a shop put gauges on it and adjust the pressures so they are correct, don't just dump refrigerant into it assuming it's low.
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Old 05-27-2012, 06:22 PM   #3
BoostedMKIV
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Thanks...I was going to add...it's more of a spraying/clicking sound....almost like a blowoff valve...of course I am non turbo lol
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Old 05-27-2012, 06:23 PM   #4
BoostedMKIV
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Quote:
Originally Posted by Mulder View Post
Sounds like it's overcharged and the high-pressure cutout is tripping. Have a shop put gauges on it and adjust the pressures so they are correct, don't just dump refrigerant into it assuming it's low.
Will time even out the pressure? Or will something eventually breakdown if I just let stay overcharged like that?
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Old 05-27-2012, 10:22 PM   #5
Mulder
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Quote:
Originally Posted by BoostedMKIV View Post
Will time even out the pressure? Or will something eventually breakdown if I just let stay overcharged like that?
Unless there is a leak the pressure will not come down on its own. It is not good to leave it like that, get it checked and fixed.
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Old 05-27-2012, 10:48 PM   #6
REDrexsti
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Quote:
Originally Posted by BoostedMKIV View Post
Thanks...I was going to add...it's more of a spraying/clicking sound....almost like a blowoff valve...of course I am non turbo lol
There is a pressure relief valve that will "blow off" excess pressure if the high psi cutoff switch doesn't stop it or has failed. Better get some gauges on it and see whats up. Like the others have said, most likely overcharged if you added to a full system.
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Old 05-28-2012, 12:51 AM   #7
rick-l
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How many seconds is a few? 30-40?
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Old 05-28-2012, 07:03 AM   #8
BoostedMKIV
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Quote:
Originally Posted by rick-l View Post
How many seconds is a few? 30-40?
Yep. that sounds about right.

Takin it by a shop tomorrow. Thanks guys.
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Old 05-28-2012, 09:44 AM   #9
NitroTrike
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Quote:
Originally Posted by BoostedMKIV View Post
Hey guys...

Here's the deal; I have a 2004 RS, with 120K miles on it, and the AC has worked great for a very long time...until I had the belts replaced and the harmonic balancer replaced.

Ever since then, the AC compressor makes this loud audible CLICK every few seconds while Im driving that can be heard across the street! Plus it feels like it's parasitic and makes the engine lose power every time it does it.

Upon first inquiry, everyone told me I was running low on refrigerant, and thats why the compressor was cycling over and over...SO, I bought some refrigerant and upon hooking it up to the AC port, realized my system has plenty of freon and the pressure is just fine. Air blows SUPER cold.

Can anyone PLEASE tell me why the compressor is still clacking super loud while I'm driving??? It's ONLY when I'm driving with the A/C ON...by the way.

Thanks!
You stated the noise came when the belts were replaced. What you're probably hearing is the belt flopping when the clutch engages - or they didn't tighten something else. Double check their work - oh and tighten the belt too.

Define "super cold". Overcharging 134A will have a negative effect on output temps. The days of "more equals colder" are long gone.
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Old 05-28-2012, 12:09 PM   #10
rick-l
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Quote:
Originally Posted by BoostedMKIV View Post
Yep. that sounds about right.

Takin it by a shop tomorrow. Thanks guys.
On my 2003 there is a thermoswitch on the evaporator that opens just above freezing. On a warm day it turns the compressor on and off pretty frequently and you do notice the car bog down.
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Old 05-28-2012, 09:15 PM   #11
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Getting something similar on mine. Recharged the system yesterday as it wasn't really making cold air. . .
Now, it'll run fine for 10-15 minutes, pressure looks good, bit low even on the Vatozone recharge gage. . .
BUT. . .after that 10-15 minutes, it'll start cycling pretty rapidly, and if the car's any higher than idle, it'll sound like a cheap BOV going off. . .
I'm thinking high-pressure, and I did bleed some off thru the charging hose, but I'd rather not just get into an endless cycle of charging and pissing it away again. . .
I'm seeing the pressure in the OK zone at idle, going low off idle, up to 2.5-3K, then spiking WAY high when the compressor cuts out. . .
Any A/C techs care to chime in. . .or is it time for me to bite the bullet and get a proper manifold and charge the thing by the book. . .
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Old 05-29-2012, 09:42 AM   #12
NitroTrike
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Quote:
Originally Posted by motohippy View Post
Getting something similar on mine. Recharged the system yesterday as it wasn't really making cold air. . .
Now, it'll run fine for 10-15 minutes, pressure looks good, bit low even on the Vatozone recharge gage. . .
BUT. . .after that 10-15 minutes, it'll start cycling pretty rapidly, and if the car's any higher than idle, it'll sound like a cheap BOV going off. . .
I'm thinking high-pressure, and I did bleed some off thru the charging hose, but I'd rather not just get into an endless cycle of charging and pissing it away again. . .
I'm seeing the pressure in the OK zone at idle, going low off idle, up to 2.5-3K, then spiking WAY high when the compressor cuts out. . .
Any A/C techs care to chime in. . .or is it time for me to bite the bullet and get a proper manifold and charge the thing by the book. . .
A few more details would help. You stated you "recharged" it. Was the system opened to replace something? How much did you put in it?

You should never EVER rev it that high when sitting still unless you have a big fan or garden hose cooling off the condenser coil. What you're hearing is the compressor stalling or possibly the high pressure popoff valve (did it sound like a whoopie cushion?).

What was this "good pressure"? Both the high and low side pressures will vary with the ambient air temp. Without knowing what the high side is / was, it's hard to diagnose.
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Old 05-29-2012, 01:23 PM   #13
motohippy
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Thanks for the input. . .some more details:
The recharge was to replace refrigerant lost from what I'm guessing is a VERY slow leak somewhere. . .I last put some stuff in 2 years ago, and it's been fine up til this summer.
As far as how much pressure is in there. . .I'm just using the cheap gauge that came with the recharge kit. . .it just has red, yellow, and green zones on it. . .at this point, on idle, it's barely at the low side of the green one.
You're describing the sound pretty well. . .also, it's made a noise that best sounds like a harmonica while being strange. . .sound stops instantly when I turn off the A/C.
As far as the quantity added. . .it took a 12oz can. . .seemed like a lot at tht time. . .
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Old 05-30-2012, 09:16 AM   #14
motohippy
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Default Some resolution

So I bit the bullet and picked up a cheap manifold gauge set from HF. . .
FSM says that at idle, ambient temp around 90, I should be looking at 30-40psi on the low side, 180-210psi on the high side.
Actual pressure was at 35psi on the low side, right in spec, but the high side was reading 250psi. . .
Bled the pressure down to spec, and the system seems to behave. . .
Lesson Learned: Buy the right tools for the job!
That said, I'm not quite sure how Vatozone, etc can sell the kits that recharge based on low side pressure. . .if I'm reading the FSM correctly, you need to be WAY low on refrigerant before you see that go low. . .
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Old 05-30-2012, 09:29 AM   #15
NitroTrike
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Watch out with those HF gauge sets - The gauges themselves seem to be decent but I had 2 leaking yellow hoses from them. The valves are also "backwards" (not righty tighty lefty loosey), so they can be a bit confusing.

As far as your numbers, the lows are about what mine are, but my highs are below 200 for the most part with 165k on the original compressor and everything else. It's just a matter of time before my compressor wets the bed lol

You have to remember the FSM numbers are in a perfect environment... blah blah temp with blah blah humidity.

According to the chart below we're both screwed on the low side numbers lol

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Old 05-30-2012, 10:22 AM   #16
motohippy
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Thanks for the chart! As far as the HF gauges. . .I was a bit surprised when I saw the thing reading pressure when I thought the valve on the connector was 'closed'. . .and even more fun trying to get the high side hooked up til I realized just how the thing was meant to work. . .
I'm thinking that +/- 5 psi shouldn't make a huge difference, but +50 probably did. . .
Also, the FSM values are for 1500rpm (if I'm reading it right. . .). . .that dropped my low side down to the upper 20s, and kicked the high side up over 220. . .
FWIW, the low pressure switch cuts the compressor off at 25psi, and brings it back at 27. . .
High pressure switch cuts the compressor out at 398psi.
The relief valve pops at 540psi
I really need to read these things BEFORE I start screwing around with stuff. . .
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Old 05-30-2012, 10:37 AM   #17
NitroTrike
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Quote:
Originally Posted by motohippy View Post
Thanks for the chart! As far as the HF gauges. . .I was a bit surprised when I saw the thing reading pressure when I thought the valve on the connector was 'closed'. . .and even more fun trying to get the high side hooked up til I realized just how the thing was meant to work. . .
I'm thinking that +/- 5 psi shouldn't make a huge difference, but +50 probably did. . .
Also, the FSM values are for 1500rpm (if I'm reading it right. . .). . .that dropped my low side down to the upper 20s, and kicked the high side up over 220. . .
FWIW, the low pressure switch cuts the compressor off at 25psi, and brings it back at 27. . .
High pressure switch cuts the compressor out at 398psi.
The relief valve pops at 540psi
I really need to read these things BEFORE I start screwing around with stuff. . .
Yeah, some guys get themselves in waaay too deep really quickly and some hurt themselves because they either get really bad advice or just wing it.

Have you ever seen what happens when someone adapts a 1 pound can to the manifold gauges and tries to open the high side valve - or worse yet puts liquid into the high side? It's not pretty. There's a reason the single gauge kits you attach the cans to only fit the low side. The end result is nothing short of catastrophic.
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Old 06-01-2012, 06:00 PM   #18
motohippy
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I'm going to guess that the pressure in the cans is something less than the pressure on the high-side. . .
Can't see that going well at all. . .
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Old 06-10-2012, 01:30 PM   #19
BlueWagon02
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I'm having the same issues, with a slight "knocking" sound from my A/C. Seems to blow cold air fine, except when the car gets extremely hot like when I don't park in the shade. I'm probably going to pick up a set of gauges from HF as well to verify the system is overcharged. Any tips on how to properly bleed the system, or is it basically like letting air out of a tire?
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Old 10-31-2012, 12:51 AM   #20
BoostedMKIV
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Just an update on this A/C problem i was having.

Here was the solution:




Now my A/C blows ice cold...and I have an extra 310hp too
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