Very intermittent flashing AC light

[scoathy]

I’m still getting an intermittent flashing AC switch light. When it starts flashing, I turn the ac switch off and back on and it quits. This is after hours of time and money spent, the ac system replaced (with the exception the revolution detecting sensor and AC control console). I believe every other part has now been swapped. There were leaks galore… haha

The AC is blowing between 35 to 40 degrees below ambient temperature at the vents then suddenly the light begins flashing and I get hot air. I hit the switch to turn it off... wait a couple seconds and turn it back on and it works fine again
.

Following the possibilities from the Camry shop manual:
Problem = A/C switch indicator flashing
Possible cause = Drive belt slipping, Revolution detecting sensor faulty (w/Power steering), A/C amplifier faulty

I replaced the AC Amp with one from the salvage yard but get the same results, the drive belt does not seem to be slipping. It is a new belt and was removed and reinstalled when the compressor was replaced and a few days later when the alternator was replaced and seems snug…

The revolution detecting sensor is possibly the culprit but how do I test it at 68 degrees F? If I remove the sensor and take it in the house, I lose all the Freon/oil in the system but it will not reach 68 degrees around here until October... Is there a trick to confirming it is working properly or is this simply one that must be completed at the AC service shop?

CHECK REVOLUTION DETECTING SENSOR
Using an ohmmeter, measure the resistance between two terminals of the sensor.
Specified resitance: 100 – 130 _ at 20°C (68°F)
If resistance value is not as specified, replace the revolution detecting sensor.

From http://www.ehow.com/about_6666335_19...-problems.html an article posted in 2010:
Failure of the air conditioning revolution sensor and expansion valve is quite common in second-generation Camrys, including the 1990 version. Auto mechanics can repair the sensor for around $125 for parts and around $98 for labor, and the valve for around $140 for parts and $163 for labor.


Open to ideas. I've researched the documentation I had along with documentation members have sent me to no avail. Willing to bite the bullet and go to an AC shop but want to be sure before I do so...

[nopain00]

Did you try measuring the resistance at the ambient temperature? I think for a lot of resistance values, the FSM gives a reference temperature just because that's how it's calibrated/measured at the factory, not because the resistance changes drastically with temperature. My guess is that whatever the ambient temperature in TX is, the 20° or so it varies from 68° is not going to change the reading much.

[scoathy]

Originally Posted by nopain00

Did you try measuring the resistance at the ambient temperature? I think for a lot of resistance values, the FSM gives a reference temperature just because that's how it's calibrated/measured at the factory, not because the resistance changes drastically with temperature. My guess is that whatever the ambient temperature in TX is, the 20° or so it varies from 68° is not going to change the reading much.

Gonna try this in the morning actually. ToyoMoho over at Camry Forums.com had a similar suggestion, recommending I try it early in the morning so ambient would be as close to spec as possible.

Fingers crossed.

Thanks!

[Doctor J]

The rpm sensor is the hall effect sensor.
the a/c computer amplifier compares the tach signal and rpm sensor signal to see if they match.
When indicator is flashing is there any unusual noise during this time?
the belt my be slipping
you may have overcharged system or incorrect oil in it (especially if it has been converted to R134)
the clutch coil or clutch relay may be defective (rare but possible)

[scoathy]

I tested the revolution detecting sensor on the compressor today. it tested within the specified range so that is good. What I did find, however, is the two wires that come off the sensor are both VERY chaffed right at the sensor, to the extent that there is no insulation at all on either wire for the first 3/4 inch. What's worse is the two wires were crossed over one another.
I'm not positive, but believe that the crossed wires could cause the intermittent flashing as the wires were not touching but were close enough that bumps in the road and vibration of the engine could cause those wires to arc. I've got no proof that this is the cause, merely speculation at this point. For now I have wire taped both wires while I try to figure out a permanent solution that does not require sensor replacement.

Doctor, thanks for the response. there is no additional or unusual noise when the light flashes.

The little gauge I have is actually measuring the freon low now. gonna drive it tonight and tomorrow and see if the light begins flashing again then get the freon level checked professionally on tuesday. will keep everyone posted