Camry A/C Compressor

Try jumping the pressure sensor switch connector. If the compressor runs replace that sensor. Do the same with the temperature sensor as well. Only do this momentarily just in case your charge in insufficient you won't damage the compressor. This link may be helpful to you.

(page 11).

There aren't too many things to go wrong, and a competent AC Guy should be able to track down the exact problem inside a half hour. Fixing it might take longer, but that will get you a real answer.

Or get the Factory Service Manual and work your way through the troubleshooting tree chart on AC problems.

Power to the system, power to the heater blower, power through the dashboard controls. Proper grounds to everything.

The AC Amplifier module, the refrigerant pressure switch, the compressor crankshaft rotation sensor (*) and the electric clutch coil on the compressor.

(*) Theory of operation: The compressor crankshaft rotation sensor connects to the AC Amplifier Module, and that module compares the compressor signal to the tachometer signal. If the compressor belt starts slipping or stops turning altogether compared to Engine RPM, it may mean the compressor has locked up, or the compressor clutch is slipping which can also lead to an underhood fire.

The AC Amplifier cuts off the compressor clutch, hopefully *before* the fan belt driving the compressor burns through or snaps - which could leave you stranded without an alternator, power steering, water pump, radiator fan, or other critical items driven on the same belt. You can drive without Air Conditioning, but not without that other stuff.

If the compressor drops out and the blue AC Control switch lamp on the heater control panel starts blinking, the AC Amplifier safety circuit has tripped. If you just drove through a puddle when it tripped the belt got wet and slipped, that's enough.

Oh., and the refrigerant pressure switch keeps the system from starting if the pressure is too low (out of refrigerant) or stops it after it gets running for a little while if the refrigerant charge is very low or there's a blockage inside the refrigerant system. (Metering orifice.)

And it cuts off if the refrigerant system pressure gets too high - among other things if the refrigerant is overcharged, clogged radiator and condenser coil airflow, or the electric condenser fan (if equipped) isn't starting. Or again, a blocked orifice.

And any moisture inside the refrigerant system can cause much craziness - but that's a whole 'nother post that has nothing to do with the electrical parts of the system.

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Gentlemen -

Thank you immensely for some very useful information. I have a few follow up questions at this point.

1. Jumping the compressor. Everywhere I look people say to do this to check if the compressor is working....well...easier said than done? Ph@Boy's link was extremely helpful and the wiring diagram (5S Engine) shows a "Triple Pressure Switch." After researching the jumping issue I understand that I can only do this with a two wire pressure switch, general consesus is that doing it with a Triple wire switch or using the wiring connector that connects the compressor to the alernator would be a very bad idea. So where is this little switch I need to jump? Is this a trick for an older A/C system and not a newer one? I see the 4 prong electrical connector running from the compressor to the alternator, there is a small wire running from the compressor to the clutch but when I undo that connector there is only one prong in it.

1. Looking down the road how do I tell if the compressor is bad or if the clutch is bad? E.g. how do I determine if I need a whole new compressor or just to rebuild the clutch?

3. > If the compressor drops out and the blue AC Control switch lamp on

This is indeed happening, my wife says the A/C worked when we bought car in 2002 and then it just "stopped" working. I print off the A/C Amplifier Circuit Inspection Sheet from Ph@Boy's link to test it.

The instructions read like this: (page Ac-66)

Tester Connection Condition Specified Condition

5 - Ground Constant Continuity 9-13 Constant 1.5kOhms at 20*C (68*F) etc etc

Will going through this reset the tripped AC Amplifier Switch? How do I do that? Also, when it says "5-Ground" does that mean I take a wire and stick it in the #5 slot and run the wire to a ground? Or does it mean clip my Continuity Tester to a ground and then poke the tip in #5 to see if the light comes on?

Thanks again for the help thus far, and for your patience in moving me forward! Huzah!

Sincerely,

Blake

Looks like my post got mis-formatted, let's try again!

Tester Condition Specified Condition

5-Ground Constant Continuity 9-13 Constant 1.5kOhms at 20*C (68*F) etc etc

After all this reading and running in circles I decided to start at square one and put a manifold gauge on the static system:

LOW r134a -4

22 psi/inHg

HIGH r134a -5

20-25 psi/inHg

Does this shed any light?

The system should be running. Am I correct in interpreting your readings were taken with the compressor off? That won't do much good. You have to get the compressor running. If it was running, the high side reading is really low.

I tried again with the car running this time.

LOW

-2.75 r134a

-25 psi/inHg

HIGH

-4 r134a

-25 psi/inHg

No cold air from the A/C, the blower was blowing and I took a long screw driver to the compressor to try and listen for clicking or signs of it "working." No clicking but I could hear vibration but it could have been from the whole engine going.

Any ideas?

Blake

You should be able to visually observe the electromagnetic compressor clutch engage and rotate. If it's not engaging the compressor is not going to work. Your high side reading kind of indicates that.

I forgot to mention that as a last resort, if you can determine using the electrical schematic, which terminals from your four wire connector are voltage to the clutch, you could use an outside 12 volt source (battery) and energize the clutch through it's harness/terminals. That may help determine which component is faulty.