2000 S70 A/C quit working after alternator replacement?

ice cream kid · Post by **ice cream kid** » 12 Jul 2015, 09:04

Hi all,

Long-time reader, first-time poster.

So a few days in a row last week, my AC would run fully cold for 10 minutes, then start blowing warm air. Turn off AC, wait, turn it back on, blows ice cold for a few minutes, then warm again. AC clutch shim problem, right? Well, a few days ago, my alternator up and quit on me while driving. I had it replaced and now the AC doesn't blow cold AT ALL. Did something get fried when alternator died? Is there some reset necessary?

Also, I've read just about every AC recharge thread I could find on this forum and I still have a couple of questions (due to conflicting info or a general lack of clear info about my specific year/model):

- Is there only one recharge port on this car? I find the one along the AC line on the passenger side (see attached pic). It sounds like there's typically a high port and a low port and filling into the wrong (high) one could cause some uh-ohs.

-What is the ideal range of pressure to fill the system to (in psig)? I understand the process of vacuuming and then adding a known amount of R-134, but I was hoping to read the pressure, add some refrigerant if it's low, and see if topping it up fixes my issue. Leaving the car at a fix-it shop for a day or two is really hard re: getting to and from work.

Thank you for any and all help and please have mercy on me - I can build you a house, I work as a Civil Engineer, but working on my own cars is a new and scary process.

Post by **Ozark Lee** » 12 Jul 2015, 09:36

There is only one port and it is the low side port but based on the background I wouldn't just start dumping in R-134A. A low charge typically presents with a rhythmic cycling of the compressor unless it is very low.

I still suspect a clutch issue. Have you measured the clutch gap with a feeler gauge? The clutch has a short period where it will work and then not work as you described but it quickly gets to a point where it won't engage at all. I have used a stick to poke the face of the clutch to see if it goes ahead and engages but that is a fairly dangerous practice

There is no optimum pressure since it all depends on ambient temperature, the temperature inside the car, how clean the cabin air filter is, fan speed, etc. The optimum charge is done by refrigerant weight but there are some ballpark numbers that will get you close enough. If you have a gauge set, on a hot day, you will see pressures well in excess of 100 PSI as a static pressure and it will be in the mid to upper 40 PSI range with the compressor operating.

...Lee

Post by **abscate** » 12 Jul 2015, 09:40

You can't fill it using a pressure reading. You have to have the system working correctly, then equilibrate it, then read the pressure.

Two 10 mm bolts will let you drop the pan from under the engine, from where you can see the AC compressor clutch gap. Take a picture and we can tell you if the clutch gap is too big.

ice cream kid · Post by **ice cream kid** » 12 Jul 2015, 10:12

Thanks for such quick answers, gents!

I, unfortunately, don't have a garage or level driveway in which to stand the car up and remove any pan from the bottom. I bought one of the Refrigerant recharge cans from the local auto parts store that comes with a gauge attached to the can. I was under the impression that one checked the pressure upon connecting and if it was too low, you simply charged it up to a target pressure range.

Post by **Ozark Lee** » 12 Jul 2015, 10:26

When you hook up the can with the gauge it will typically be well into the red danger zone, even if the charge is low. The gauge reading is only valid when the compressor is running and even then the green zone needs offsets for temperature. The instructions with the can typically explain their methods and provide some ballpark offsets.

Unless you can get the compressor running the gauge is of no value.

...Lee

Post by **dosbricks** » 12 Jul 2015, 10:31

If you plan to own a 15 y.o. Volvo you should plan to work on it yourself or the car will devastate your budget in shop repairs. Buy a pair of ramps and drive it up on them facing downhill. Block the rear wheels and set the e-brake.

As abscate and Lee said, the clutch must be engaged, controls set to full cold, before adding refrigerant.

ice cream kid · Post by **ice cream kid** » 12 Jul 2015, 11:00

OK. Any visual or audible clue as to whether the compressor is running or not?

Post by **Ozark Lee** » 12 Jul 2015, 11:08

You can see the compressor running but it can be a bit difficult. The face of the compressor clutch will rotate along with the pulley when it is running and it will be stationary when it is not running. Since it is at the bottom of the serpentine belt path the angle to actually see it makes it tough to discern. A "mirror on a stick" can be quite helpful.

...Lee

GGs98S70 · Post by **GGs98S70** » 14 Jul 2015, 18:50

I have a similar issue only the battery died. Ac worked fine before replacing the battery. Now, the compressor does not engage. Tried most of the diagnostic procedures but no luck yet.
Disconnected the battery twice for an hour each, shorted the low pressure switch, grounded the high pressure switch to ground, checked both the relay and fuse, both meter good. Green light comes on the controls. Mine is a 98 s70 base.