AC keeps going on and off

[sabbates]

The AC on my wife's 2001 V70XC keeps going on and off.

Does that usually indicate a low charge?

Should I check low side and high side pressures?

[JRL]

No, if it's cold when it's on your compressor clutch is failing
Search for the ghetto fix, the BREAD CLIP repair

[hoonk]

Have not tried the "bread clip method" but have fixed many compressor engagement problems by resetting the clutch gap. There are shims under the outer pulley that can be removed to compensate for a worn clutch. Gap should be ~.3-.5mm, larger than about .8 and the compressor clutch may fail when very hot. You have to remove the 4 bolts holding the compressor to the engine to be able to get enough room to get the outer clutch off. You may want to source some extra shims before you dismantle the clutch if you decide to use that method. (to be able to have the correct size shims available - the correct size never seems to be already installed :) )

[JRL]

Bread clip fix, 10 minutes for someone who has just a little talent!

[sjonnie]

There are shims under the outer pulley that can be removed to compensate for a worn clutch. Gap should be ~.3-.5mm, larger than about .8 and the compressor clutch may fail when very hot. You have to remove the 4 bolts holding the compressor to the engine to be able to get enough room to get the outer clutch off.
It can be done directly through the PS wheel well (http://forums.swedespeed.com/showthread.php?158177-I-ve-had-it-Help-with-a-Volvo-A-C-ghetto-clutch-fix). No need to remove the compressor.

[JRL]

Can be done from the top., easy peasie!

[sabbates]

So if I understand the bread clip method, the clutch will constantly be engaged, correct?

Don't you run the risk of damaging the compressor in cold weather?

[hoonk]

It can be done directly through the PS wheel well[/URL]. No need to remove the compressor.

I spend a few minutes removing the 4 bolts on the compressor because the small ac clutch removal puller I own is too big to fit between the compressor and frame rail :(

[2002V70XC]

I spend a few minutes removing the 4 bolts on the compressor because the small ac clutch removal puller I own is too big to fit between the compressor and frame rail :(
I think you can use 3xm5 bolts to remove the clutch. I haven't done it so I'm not sure but that was the result of my research.

[JRL]

So if I understand the bread clip method, the clutch will constantly be engaged, correct?

Don't you run the risk of damaging the compressor in cold weather?

No, you're just placing it back to where it's supposed to be, still disengages

[Iroll_]

Might seem odd, but when I checked the gap in the clutch-mine checked out.
I noticed that I was a bit low on anti freeze coolant ( not low enough to trigger a light):
When I bled and refilled the system, my AC starting working full time.
Not sure if it was a coincidence but might be something that's worth checking out.

[hoonk]

I think you can use 3xm5 bolts to remove the clutch. I haven't done it so I'm not sure but that was the result of my research.

yes, those bolts hold the puller onto the clutch -

7197

[sabbates]

I checked the clutch gap las night, and the gap was about .55 mm.

From what I've read, the gap should be .3 to .5 mm, so it's not that far out of spec.

I can check the high and low side pressures, but does anyone have the chart that shows the range of pressures for a given ambient temperature?

[2002V70XC]

yes, those bolts hold the puller onto the clutch -

7197

From what i've read off a thread, you can use just 3 m5 bolts to remove the clutch then use a bunch of washers with the 45mm M6 bolt to push the clutch back into place. If I need that special puller for the job, I would rather do the "Bread clip" fix. If I can find the thread i'm talking about, i'll post a link here!

[sabbates]

Might seem odd, but when I checked the gap in the clutch-mine checked out.
I noticed that I was a bit low on anti freeze coolant ( not low enough to trigger a light):
When I bled and refilled the system, my AC starting working full time.
Not sure if it was a coincidence but might be something that's worth checking out.

How did you notice you were low on A/C coolant? Did you check the high and low side pressures?

[sabbates]

Checked the AC pressures this weekend.

Without the AC clutch engaged, the high/low pressures were 110/74 psi at about 85° F ambient temperature.


With the AC clutch engaged, the high/low pressures were 255/40 psi.

The AC pipe going in to the cabin was cool, but not ice cold.

Is this normal?

[sabbates]

Here are pictures.721372147215

[sabbates]

I went out and measured the static pressures this morning, and the low/high was 50/95 psi.

I expected the pressures to equalize over night. Why didn't they? Is that indicative of a restriction somewhere?

Then, I evacuated the system and started pumping it down. The low side pressure was about -25 (psi or in hg?) when it suddenly jumped up to 15 psi, and then gradually pulled back down to -25. Then it jumped up to 0, and gradually pulled back down to -28, or so.

That seemed funny to me, too.

Any idea of what is going on?

[sabbates]

I evacuated the system, vacuum pumped it, and refilled with 1 kg of r134a. The pressures were 45/250 psi with clutch engaged.

I back probed the clutch coil connector, and verified 14 V when engaged, and 0V when it cuts out. This says to me that the problem is not a clutch gap, but that something is turning off the AC.

Like a pressure or temperature switch? There is a low side pressure switch that turns off when the pressure drops below 20 psi, or so. Are there other switches? Like a high pressure switch, or a cabin air temperature switch?

Is there a way to check these?

[hoonk]

Are there other switches? Like a high pressure switch, or a cabin air temperature switch?
Is there a way to check these?

There are at least 4 sensors that can signal the ECM to turn off power to the compressor. The outside air temp sensor (the bump on the bottom of both outside mirrors are temp sensors, don't remember which one does the ac) turns off the comp if it thinks it is too cold outside- the evaporator temp sensor (if too cold) , ac pressure sensor (too high or low) and coolant temp sensor (too hot). There is also a relay that powers the compressor clutch.

You can easily view all the temps/pressures using VIDA.

[sabbates]

There are at least 4 sensors that can signal the ECM to turn off power to the compressor. The outside air temp sensor (the bump on the bottom of both outside mirrors are temp sensors, don't remember which one does the ac) turns off the comp if it thinks it is too cold outside- the evaporator temp sensor (if too cold) , ac pressure sensor (too high or low) and coolant temp sensor (too hot). There is also a relay that powers the compressor clutch.

You can easily view all the temps/pressures using VIDA.

Thanks.

Still getting vida/Dice going on my mac laptop