A/C Light Blinking Troubleshooting Guide

Ok, so I've been on this thread for some time now. I have that annoying a/c blinking light, 2012 Toyota Tacoma Prerunner V6 2 wheel. I brought it to my shop, and they said no power was going to the speed sensor. So I went and spent the 150 bucks for an a/c amplifier, and I plugged it in before taking the old one out (which looks like a PIA), and the blinking light is still there. I don't think my shop tested the speed sensor correctly. Any input would be great, thanks

 

Does the compressor come on for a few seconds before the light starts flashing or does it not come on at all?

 

To be honest with you, I never checked and just trusted their word. I can try and see if I can make it from inside the truck to the outside and check

 

Need to check that first as that determines the diagnostic path we take.

 

Ok so it doesn't look like it kicked on at all. I could see a number and when I started my truck and put the AC on it did not move at all

 

Should be able to hear it when you kick it on, does the engine speed up a bit when you turn it on?

 

No it doesn’t

 

Interesting, so no compressor action or change in engine speed when the A/C is turned on but the A/C light fladhes?

 

Yep and I already bought a new ac amplifier and plugged it in and still blinking so left the old one in

 

That's a new one, I would expect the engine to idle up when the A/C is turned on.

Well let's check things at the MG CLT Relay, do you have a test light?

 

Nope and I can’t find my multimeter right now annoying, but I did already replaced that too

 

Grab you a test light so we can check what we're missing at the relay socket.

Test light connected to battery Ground check for power on Pin 2 & 5 of the MG CLT Relay with the key on.
Then test light connected to battery Positive check Pin 3, it should light up if the wire is continuous to the clutch coil and the coil windings are good.

If that all tests good then with the light still connected to battery Positive start the truck and have an assistant hit the A/C button while you hold the light on Pin 1 of the MG CLT Relay, it should light up briefly until the light starts flashing.

 

I will for sure try this out this weekend. I don't have someone who can help at this moment, also stupid work getting in the way lol. Thanks for the help and I will let you know

 

Ok, boys and girls, I have an A/C Amplifier part# 88650-04050 for sale, brand new I paid with shipping around $150. I am selling it for 100 and you pay shipping. Message me here or comment

 

Thank you very much for this post! Replacing the compressor pickup sensor has cured my a/c because of blinking light multiple times. I actually just repaired it today, but this time I added a lubricant to the prongs of the sensor and put everything back together. The A/C is working great again. You’ve saved me hundreds of dollars. Maybe thousands.

 

Decided to revisit this issue in my truck, a few years ago mid trip with defrost on the light started flashing. I pulled the relay and fuse for the time being and here we are now. What I know so far - I swapped to the 12+ hvac controls. The clutch does not engage no engine change. The light stays solid no blinking. I have swapped relays and snugged up the lock sensor bolt. No sound or smell when it stopped. Strange that with the 05 hvac controls it flashed but with the new wired in 12 it doesn’t. Everything else functions properly though. I am leading to think it’s the amplifier as it’s not even trying to come one. Thoughts or direction where to start?

update-
I jumped the relay the clutch tries to engage but is bound up. Rubber smell if I leave it in for a few seconds. I’m assuming it’s just the clutch that’s bad?

 

Need to see if you can turn the compressor shaft by hand, if it's locked up it needs a compressor and if there's metal contamination a condenser, expansion valve filter, flush the evaporator & all of the lines and I'd recommend an expansion valve since you have to have it off to flush the evaporator.

 

Well that’s not cool news. I slacked the belt and could not get it to turn. I’ll buy the whole kit from rock auto just need to decided what brand, uac or gpd. What’s the best way to clean the lines out?

 

I use a flush gun at work and then blow it out with compressed air but they make flush in a pressurized can as well, you still need air to blow it out.

Also need a way to pull a vacuum on the system when you are done putting it back together or have a shop evac and charge it.

 

Ok thanks I can have the shop guys at work vacuum/charge it. I’ll look into the flush kits. Thanks!