Toyota Repair: 92 Paseo, singer sewing machine, things on my mind

Question
QUESTION: Is there a fix for a bad wiring harness? Flashing AC light and no AC from time to time. Aso battery light comes on most likely due to same problem. Is there a specific area to look to for the bad wiring? We just got this car for my son, who bought it with his hard earned money... your suggestions are appreciated. Thank you in advance.

aw

ANSWER: Hi Alan,
 Toyota doesn't usually have problems with a wiring harness,
unless someone was messing around with it. If you had a harness
problem there would be a lot more issues. The A/C light
is suppose to act that way because of certain issues like low
freon or the accumulator valve is dirty or bad.
Battery light means no charging, very easy to
check with a multi-meter on the battery while the car is idling,
should show approx. 13.5 volts, if it shows 12 volts the alternator
is not charging. How many miles on car? What has been done to car?
What has been replaced recently? Has an amp been installed in car?

Tim.
ToyDoc

---------- FOLLOW-UP ----------

QUESTION: Tim - we got this car about a month ago. 189,000 miles and had been in one family since new. The engine is the 2nd one in the car with about 60K on it runs like a singer sewing machine. I had seen several other references to bad wiring harness when researching the AC flashing light issue.

Where can I locate the accumulator valve? And how do I check it to see if it is dirty or bad. I have a voltmeter checking the alternator is no problem.... that seems to be a minor issue. It's been 100 degrees past couple of days here in NC getting the AC working properly is top priority.

When I initially got the car charged the AC with one can of 134a and it got cold immediately. I can check or change the accumulator valve just gotta know how to locate and test.  

Answer
Alan,

Sorry, I meant expansion valve, too many things on my mind. Its buried up under the dash in the cooling unit, small rectanguar block that the freon lines tie into, its bolted to the evaporator.
Rather then replacing parts, you really need to have a A/C expert hook up gauges to the system to pinpoint the problem. It could
be low freon, exp valve, A/C amplifier, or some other part.

good luck, let me know.

Tim