A/C Light Blinking Troubleshooting Guide

Seems low for that ambient temp if you have the blower on high, low side is pretty close but I would expect the high side to be somewhere in the 140-160 range.

Run the truck A/C on, blower on high, and see if the suction line exiting the firewall is ice cold, if it is your probably good. If it's not then your probably a bit low.

 

That mid-pitched, resonating whine I heard was the rubber letting go on the AC clutch. See the little rubber remnants in the pic below:

Bonus part number for the clutch (check fitment for your particular year and model):


My truck is a 2015 with about 153K miles. I don’t think it’s the miles more-so the age of the clutch..

 

Ugh, so I turned on the truck today to see if the low pressure line was cold while running, and the A/C shut off again! Now no matter what I press the button and then it blinks in about 5 seconds. Unlike last time, I see that now the clutch is engaging and can see the pressures respond on the gauges. The air does get a bit cold by the end of the 5 seconds. At the end of a long drive the clutch was hot, probably from the rubbing that I mentioned earlier with not having the correct air gap. I figure that this may not be great, but is not what is causing my issue, because the clutch spins and stops when the car computer commands it. After the long drive back home I did not notice that the clutch was as hot.

So the blinking light has to do with the RPMs not matching on the drive belt and the compressor right? At this point, the item that is sticking out to me is the compressor. Perhaps there is internal friction, and this is what caused the original (old) clutch to break? Then I put on the new clutch and the compressor works again, but now it is still so bogged down that the lock sensor freaks out and stops the party? I could take off the sensor and test AGAIN, but it was fine a few days ago, and it seems suspicious that the clutch would fail and then days later another totally unrelated part would fail.

Assuming it is the compressor, can someone recommend which to get on RockAuto?

 

Without scoping the lock sensor signal it's hard to say, could be a wiring issue on the lock sensor circuit as well.

 

I do still have the replacement lock sensor I am returning. I guess I will put that one on and see if the problem is fixed. If not, I will try to find how to test its wiring. I will let you know if neither of these come up with anything. It may be a little bit, as life and a leaking oil pan will probably take precedence for a while.

 

Well, I had a few minutes this morning and tried out the replacement sensor, and lo and behold it seems to fix the issue! The truck is handicapped right now due to a leaking oil pan (which will be "fun" to replace in my driveway, especially since I have the 4X4 2.7L so the front diff has to come off). but I may turn it on and run it a bit every day for the next few to see if at least the A/C is solved. I may still need to alter the pressures, but that will have to wait until the oil pan is done.

It seems a bit strange to have two issues manifest basically at the same time. First the clutch got shredded, and then about 1wk later the sensor does not work. I will test the old sensor again to see if the simple bench test reveals any issues, but I suspect it will pass the bench test again. I will report back if it fails it this time.

I guess this is perhaps a case of a sensor being "OK" but actually not behaving how it should. BTW, contacts were cleaned on the old sensor before reinstall, and the area of the compressor was wire brushed.

 

For the last 2 years, I occasionally get the flashing compressor light. The occurance was less than once a month, but happens now every couple of weeks. Turn off, turn on, works perfect. I might have to try the relay first, then Compressor pickup sensor.

 

Hey guys! My name is Nate. I am having the blinking light of doom. This forum has been super helpful, and I have narrowed it down to 88346-04010 the compressor pickup sensor. I have already tried : relay, pressure test, check ground, new compressor (needed anyway), and amplifier. Today I took the sensor out and tested it and it is not functioning properly. Also, the sensor appears to have cracks in the housing. Trouble is, I can not find one of these sensors anywhere. I have back ordered one with no ETA from the dealer. Checked local scrap yards and used parts places. Checked ebay. Even checked FB Marketplace for parts trucks. Does anyone here have a lead on where to get one, or have one for sale? I also have an AC Amplifier brand new in the box (Took out to see if it was my problem) that I would love to sell to someone on the low.

 

This place seems to have some.

 

Hi! I just want to give my experience with this common Blinking AC Light problem. My light started to blink often, almost every day and I needed to press the AC button more than 10 times until the AC started to work. The magnetic clutch relay is good. When the clutch engaged the compressor worked well, so the problem wasn't there. So I slipped down under the truck and removed the Compressor Pickup sensor. This is a very uncomfortable job! I needed to remove the metal cover and some square fabric cover to touch the sensor.
The sensor is attached with only one 8mm hex bolt with Philips head, YOU NEED A SMALL WRENCH TO GET THIS BOLT LOOSE! After that, you can work with a Philips screwdriver. My sensor was good after I tested it, so I just cleaned it with alcohol and a soft rag. But I think the very important thing is how the body of the sensor is attached to the compressor. IT NEEDS TO BE TIGHT! My sensor was a little bit loose, I didn't feel a good resistance as one element of the car engine should be! This small plastic pod is attached with just one bolt and there are a lot of vibrations! So I believe the sensor was loose and the signal from the compressor rotor was weak, the AC Amplifier didn't read it correctly and the light started to blink, and the AC went off. So before you attempt to remove the sensor FIRST JUST TIGHT IT!
Also, it is very hard to find this part! The dealers want to replace the compressor(not just the sensor) and the price is about $1200 here in Florida.
Hope this will help!

 

Hello, i have been experiencing a failing a/c for the last year or so. It was working intermittently for a while, then it stopped working completely. The button blinks when i turn it on, so i had not been using. Recently i turned it on by accident and the magnetic clutch completely burned up, although im sure this was a gradual thing. I installed new magnetic clutch, turned on truck and a/c. The clutch engaged and was getting very cold air for about 20 seconds, then it disengaged. I cannot get it to work again. The belt pulley spins fine with the belt off. Is this a compressor issue or low refrigerant issue? thanks for any help

 

My problem was the same. First, try to tighten the bolt that holds the sensor to the compressor. Mine was just loose.

 

Check the wire that engages the clutch didn't fall off/break

 

After 3 years of intermittent AC blinking light, I 1st tried clutch relay and then compressor pickup sensor, which fixed the problem. Thanks to JCH for his comprehensive guide and solution.

 

Where did you find the compressor pickup sensor?

 

Gateway Toyota in NJ. Best price after searching a couple months ago. The part was backlogged for a week or so, but the dealer personally called me to let me know that. Got it for $101 after a discount. Arrived at my home in Texas just fine. Not sure if this price will hold, but it was by far, the best price plus great service.

Gateway Toyota
395 Route 37 East Toms River, NJ 08753

• Sales: (732) 573-4124
• Service: (732) 573-4984
• Parts: (732) 573-4785

 

Thanks for your help, got a/c working correctly however i did notice that after driving for about an hour the compressor clutch (which is new) is very hot to the touch. Everything else works as it should. Is this normal? It seems like it may eventually wear out the belt from the heat.

 

My A/C knowledge is too limited; wish I could help with that.

 

my 2008 tacoma has this problem, ac light flashes immediately after turned on, clutch turns off. clutch relay is good, compressor sensor is good (i tested and tried 3 other used ones), replaced amplifier, still same. mechanic says it could be a temperature sensor near evaporator under dash. i replaced the compressor with clutch, still same problem. noone on this forum has mentioned a temperature sender? only way i can use ac is to remove clutch relay and run a jumper wire in its place. i was thinking of just using an aftermarket switch to turn the ac on and off, but i do not see where to ground a wire in harness to turn clutch on other than at the terminal to the clutch relay, and that may be difficult to add a wire there with relay plugged in. which terminal (or color wire) at the amplifier that an additional switched ground wire can be added to that would turn clutch relay on? there must be another cause for the flashing ac light other than what haa been discussed here.

 

The evaporator temp sensor will not cause the light to flash.

First thing we need to know is does the compressor clutch engage for about 3 seconds when you turn it on and then disengage when the light starts flashing or does it not engage at all?