Help with charging a/c

atlgadawg · Aug 13, 2008

I have a 1996 Ranger with 4.0L and the A/C compressor has been switching in and out every few seconds for a while. I was hoping the R-134 was low so I bought a can of straight refrig. (no stop leak) and a install hose with the cheap red/green gauge. I checked the pressure first and when the compressor kicked in the gauge dropped to low (less than 40) and the compressor cuts out. While the compressor is off the pressure would rise to 90 or so and it would kick back in and the pressure would drop again. I slowly added some 134 and finally the compressor would stay on and the gauge stabilized in the green 60-80 or so. Suddenly the compressor started making noise and the belt started smoking. I cut off the compressor quickly and I am wondering:
Did I need oil or something with the 134?
Could the clutch be bad since it has been cutting in and out every few seconds for a while and now it has a load on it?
Too much 134?
Is the A/C shop next in my future or is there an eay way to check compressor or replace clutch?
Thanks

Bob Ayers · Aug 13, 2008

When you were charging it, did you have the can upright, or upside down?
It it was upside down, you were liquid charging, and you may have "slugged" the compressor. Have you tried it again since it has set for awhile?

MAKG · Aug 13, 2008

90 PSI on the LOW side? If it's really hot there, I suspect your pressure switch needs adjustment. It shouldn't let the pressure get over 40 PSI before turning on. If it's not really hot there, it's also overcharged. The pressure switch should turn on above 40 PSI, and off below about 25 PSI. You'll need a better gauge. It's also quite important to understand what the high side is doing.

Pressure measurements are WRONG while the charging valve is open, as the system is out of equilibrium. It takes some time for it to settle down again, once the valve has been closed.

Bob, I don't see a compressor making noise like that with a hydrolock. It should just stop and smoke the belt. I think the compressor is bad and/or the system is overcharged.

Yes, one generally does need to add oil with recharging and it is VERY difficult to know how much. This is why topping off is considered to be a bad thing. You evacuate, FLUSH, and charge with a complete R-134a and oil charge.

The clutch won't make the noises you describe. I think you need a compressor. You need a shop to at least recover the refrigerant. You can feel the bearing by turning the hub by hand (belt on or off) with the engine stopped. Normally, you can do this with some effort, but since I think you overcharged the crap out of it, it might be too much effort now.

KELLY88 · Aug 13, 2008

I've got an S-10 Blazer in the driveway with the exact same conditions you're describing. Gauge pressure fluctuating and the compressor kicking on and off intermittently. The compressor wouldn't turn on at all. I added some refrigerant and now it works intermittently but not full time. The R-134 can gauge said it was high on the pressure but still within safe operating range so I didn't add anymore. Stuck now on what to do. Let me know if you find anything out.

atlgadawg · Aug 13, 2008

I had the can upright and at "3 o'clock" every 5 seconds or so as the label on the can said. I haven't tried it since it started making noise so not sure if it's any better. I put about 1/2 to 3/4 of a 12 ounce can in slowly before stopping.
I have gauges for my home a/c but no 134 adapters. Might get some but I guess I would need to flush well between r-22 and 134. Maybe the shop would be best I was hoping that the clutch would be easy to change. Thanks

atlgadawg · Aug 13, 2008

One more thing. I have the blend door failure and when I turn on the a/c, warm or hot air is flowing out of the vents for a few seconds until the vacuum closes the hot water line to the heater core. How will that effect pressures??

MAKG · Aug 13, 2008

For a few seconds? No.

If it were continuous, perhaps. But you compensate for it with an IR thermometer and PT diagram.

And FYI, it's R-12. R-22 was used in fixed (building) air conditioners. Adapters can be found, but it's easier, cleaner, and not too much more expensive to just buy an R-134a gauge set from Harbor Freight or somesuch.

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92649

atlgadawg · Aug 13, 2008

Yeah I meant I have home a/c r-22 gauges.
I was gonna do the blend door fix by cutting the hole in the bottom of the airbox but haven't got around to it yet.
If I did blow the compressor, how do you pull the orifice tube to see all of the crap that the compressor spits out? Does the refrig need to be evacuated or is there a check valve of some type to do that?

MorePower7701 · Aug 23, 2008

R-22 gauges have different hose fittings than gauges used with R-134a, you will run into a problem when you try to attach the can tap valve with your R-22 hose.

You have to recover the charge to pull the orfice tube, if it's covered in a gray/black greasy crap, the compressor is going or has already gone bad.

Anytime you open a system you allow moisture and non-condensables in, you would need to flush and pull a vacuum.

If everything looks alright, while to system is open its a good time to replace any o-rings that might be leaking.

The A/C systems Ford used are IMO a very easy system to work on, working correctly they will get "very" cold.

skippy · Aug 23, 2008

atlgadawg said:
I had the can upright and at "3 o'clock" every 5 seconds or so as the label on the can said. I haven't tried it since it started making noise so not sure if it's any better. I put about 1/2 to 3/4 of a 12 ounce can in slowly before stopping.
I have gauges for my home a/c but no 134 adapters. Might get some but I guess I would need to flush well between r-22 and 134. Maybe the shop would be best I was hoping that the clutch would be easy to change. Thanks

Johnstone supply for the adapters or gauges,they have locations around atl and one in marrietta.

MAKG · Aug 23, 2008

Yes, but you'll need a decent PT diagram to diagnose. Those come on the gauges, but R-22, R-12, and R-134a are all different.

skippy · Aug 23, 2008

MAKG said:
Yes, but you'll need a decent PT diagram to diagnose. Those come on the gauges, but R-22, R-12, and R-134a are all different.

Pt charts are free at the counter.

UnderMedikated · Dec 31, 2008

A/C license

You can get ASE certified for R12 over the internet. You may need this to buy Freon and other A/C related items from Johnstone. I use Lenz distributing over the net for my A/C items or Johnstone locally.

UnderMedikated · Dec 31, 2008

Amazon.com has better quality gauge sets for the price of Harbor Freight gauges.
You also need an adaptor for Ford high side ports. get a multi manifold gauge that has R12/22/134 scales on it's dial.

Help with charging a/c

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