What would cause the A/C switch indicator light to keep flashing on and off?

Your AC's magnetic clutch relay could be bad, in the under hood fuse box it is labeled MG CLT (2nd from right, middle). In Toyota nomenclature it is part 90987-02028, a SPST 12-volt relay, you can test if this is the fault by temporarily swapping it with one of the other relays, such as the TOW or AF HEATER relays. The other problems that can cause the flashing AC indicator are the AC amplifier assembly or the compressor itself, but I'd swap the relay first.

Where is this AC amplifier located and how is it listed at auto parts stores?

I had this same problem last year and I replaced the relay, pressure switch and the compressor. Worked fine for a while and now just recently it is flashing again. Don't know what to try next. It sounds like this amplifier but I am not sure where it is and can not find it listed at auto parts stores as AC amplifier. Any help?

Had this problem two weeks ago on my 2013 Tacoma. Five miles into a 15 mile drive to work the A/C cut out and the light on the button started flashing. I turned it off for ten seconds and turned in back on and all was well. But this happened every day for a week. Then the truck battery died. It was six years in to a five year battery, so can't really complain. Put in a new battery, and the the A/C problem stopped immediately. Was the A/C trying to tell me that my battery was dying? No idea. But it worked for me.

The light is supposed to test the AC lock sensor and warn you when the AC clutch is slipping by comparing AC RPMs to engine RPMs. I had this happen once after recharging the system-apparently i overfilled it. Just happened again a year later-started smelling burning belt and AC stopped working on a hot day when idling in a parking space. I let it sit for a while and now seems ok.

My 2006 Toyota Avalon is having this problem on occasion... my mechanic said he cannot tell what it is because it was working fine when I took it to him.... we have already changed the relay switch... it worked fine for 2 days then started blinking again and then we took it to another mechanic of ours and he said it was working fine and gave it a Freon charge as it was low but the next day it was blinking again... not sure what to do next... I live in Phoenix AZ it's too hot to have this problem...

I am currently having this problem with the blinking light on my 2011 Tacoma. I just took it in to Toyota and they tell me that it is the compressor and the clutch. Should I get a second opinion?

I noticed this occurring on my 2005 Tacoma V6 TRD Sport - 110k miles. Within 24 hours the engine began making a loud squeal. My mechanic diagnosed a day later - my AC compressor seized up. $1100 isn't bad for a 15 yr old truck IMHO. Now I know to pay close attention to that blinking lol. Hope this helps someone.

has anyone tried using an OBD2 scanner to see if there are any fault codes?

Had this issue on my 2014 Tacoma @ 49,000 miles. Swapped the a/c relay and heater relays and the ac started working. Then when I put the relays back in there original slots the AC continued to work for weeks until my "low tire" indicator light came on one day and the AC started blinking immediately. I aired up the tire, the tire light went off and the AC resumed working immediately. Then after thinking for a few seconds it hit me! BATTERY is going out and that one extra "tire indicator" light was straining the battery just enough to not kick the AC compressor on. Went to autozone, the battery tested bad, I threw in a new battery and haven't had an AC problem since. When a battery on newer vehicles starts to strain, the ecu will start shutting off functions that aren't vital to keeping the vehicle running properly. In other words it chooses no AC over AC until battery is completely dead. Keeps you going... A dealer will never tell you that though...!!! I hope this helps others...

It's most likely the compressor pickup sensor (Part # 88346-04010) it tells the rpm of the Mag Clutch and if it is different from the engine rpm it will stop the compressor and start blinking