92 Camry 3VZ-FE V6 a/c not right after compressor & drier replacement

[danmancalif]

I have a 1992 Camry LE with a 3 liter V6 engine (3VZ-FE), assembled in Japan . The a/c was working fine until just shortly after I changed the timing, power steering and the a/c compressor-alternator belts along with the water pump and thermostat, radiator hoses and caps, plugs, wires, distributor cap and rotor AND the radiator.

The a/c worked fine since the car was new and has never been touched, recharged or anything.

A short while later, the a/c compressor started making a blood-curdling screech noise whenever the a/c botton was pushed to engage the compressor. I took it to a reputable and good, independent shop and had the compressor replaced with a new one along with the drier. The R12 was evacuated and then replaced with the new compressor.

Now the system does not quite cool like it used to. It will produce about 44 degree F air at the upper center vent when I am on the freeway, ie, higher rpm's, but does not cool well at all at idle and in stop-n-go city street traffice... but it used to. Idling in the shade in my driveway on an 80 degree F day, I measured 54 and 64 degrees F at the upper center vent.

The mechanic thinks the hydraulic fan isnt turning as fast as it should at idle and he thinks it is defective. However, when I jumper E1 to OP1 in the Data Link Connector, the fan runs fast full speed so the fan and the fan motor and the hydraulic pump are working ok.

Then, following my Haynes manual, I checked the cooling fan ECU under the glove box and found the fan solenoid cold resistance to be ok and 8 ohms (between pin 4 to ground), pin 1 was grounded and did not have battery voltage when the ignition switch is on, as the manual saiys it should (don't know why), pin 4 reads about 7 ohms to grnd when ignition is off but has 12vdc with it on, pin 5 was grounded with continuity with the throttle closed but did not open to no continuity when I pushed the throttle pedal down with the ignition off, pin 8 has no wire or pin in the connector but the manual says the a/c pressure switch should be connected there (again, it's never been touched before), pins 9-10 I did not test. So with these differences, I can't assume that my ECU is wired the way the Haynes manual says it should be.

Then I tested the 4-prong a/c pressure switch and its connector. With the connector off and the ignition off the switch reads continuity between pins 1-4 for the compressor clutch and between pins 2-3 for the cooling fan. On the connector, pin 2 is grounded and when the ignition switch is turned on there is 12vdc on pin 3 and also on pin 1.

With the a/c pressure switch disconnected and the car running, the fan runs full speed fast but of course the compressor will not come on. With the a/c pressure switch connected, the compressor runs but the fan runs at a very slow speed and after awhile starts to cycle up to high speed for a second or 2 every little while. The mechanic thinks that is the problem at idle... that the fan isn't blowing enough air at idle to cool the condenser (between the radiator and the fan) enough.

So, the questions are:

1) Should the hydraulic fan be running fast, high speed with the a/c on and the car at idle or moving less that freeway speed?

2) Are the short spurts of high fan speed every little while with the car at idle a normal for the fan?

3) With the car idling and the a/c on, should the R12 pressure raise up enough to open the pressure switch (ie, no continuity) so that the fan runs at fast speed?

4) How do I test that the fan's hydraulic solenoid is moving properly with signals from the ECU? Maybe it is not moving enough to run the fan on high when it should but does when the pressure switch is disconnected.

5) What high and low pressure R12 readings should this system have with the a/c running or not? I can't find any definitive answers online about this and the mechanic is going by what he "thinks" it out to be.

6) Could the R12 pressure be enough to engage the compressor clutch but not enough to make the fan run fast when it should or at idle?

7) I noticed a unused connector with wires hanging loose right behind the back end of the compressor. I never noticed it before so I have no idea about whether it was used before. The compressor has a connector and wires attached to it. Any idea what it is or what it is for? (I cant figure out how to insert a pic)

8) What else can be wrong with this system?

Please help.