A/C Light Blinking Troubleshooting Guide

Another success story! I did test my old sensor but it was reading high at 5v.
(Unlike OP who was reading low).
When I passed the magnet negative side the value would drop but when the positive side passed by no significant change.
Thanks OP for a great write up.
Does anyone know why the new sensor has the epoxy on the back.
(The new one has multiple colors)

 

Is there any common leak points on these? I have a 13 model 4.0 that I just got that the air is blowing, the light is staying on and not blinking, the compressor is coming on and so is the clutch, but I’m just getting warm air.

what would you guys do next? Check pressures?

 

If you have a UV light look for dye on the lines, hoses, compressor, condenser, evaporator drain, etc.
Other than that yea need to check pressures and see.

 

So my flashing AC saga is hopefully over. Dealership had the truck 3 different times for the same issue. It eventually ended up being a loose pin in the wiring at the compressor. Not sure if this was the original issue or if it was created somewhere along the way.

 

Another success story I think after years of dealing with the intermittent blinking. Seemed to happen randomly at idle or waiting stopped in traffic and would not happen at high RPMs driving on the highway, only in the high heat months. Replaced the compressor pick up sensor and it’s not happened for 3 days. Was a pain to remove the wiring harness as my 13 had a tan clip on the plug that had to be removed before I could unclip the sensor. Didn’t test the old sensor but definitely remove the front skid for easier access. Thanks!

 

Fish Taco 4x4 I would wait a couple of weeks before declaring victory.

Mine has been acting up for > 3 years, but so infrequently and only when I let it idle and only when really really hot (> 90F). Also press off and on, then works like nothing happened. So last summer I replaced the Magnetic clutch relay. The problem came back like 10 days later when about 101 and idling in front of my garage. It happened a few more times before summer ended. I planned to replace the pickup sensor, but it started cooling off and never happened again until around June 1 of this year. I've been busy, so thought to just pay someone to put on a pickup sensor.

The guy I take my truck to, I asked him to replace the pickup sensor, he said, let's replace the Magnetic Clutch Relay. I told him I already did, but he was not convinced. He put one in for free while I monitor. It has been 3 weeks, no flashing light. He said some of the Magnetic clutch relays sold are junk. He had a brand (maybe OEM) that he trusted. I think I probably got one off off Amazon or AutoZone. So far so good. I really will replace the pickup sensor if it comes back, but pretty hopeful after 3 weeks and this current heat in Texas.

 

This thread has been invaluable. I’m troubleshooting the blinking AC light on my 2012. Fuse good. Relay good. Pickup sensor seems ok (if I'm doing the voltage test correctly).
I finally noticed that the magnetic clutch has some rubber residue around the outside front. Does this look like my clutch is toast? Is there something else going on that could cause the clutch to bind up or something? Forgive me, I'm a very amateur mechanic.

 

Looks like the clutch failed, watch the clutch while you have someone turn on the A/C. If the outer part (circled in blue) rotates but not the inner part (circled in red) the clutch has failed.

If it has then you need to make sure the compressor isn't seized before replacing it.

 

LOL, came back today while at idle
Drove almost 5000 miles last three weeks all across the country no issues

 

My A/C light blinked this morning and stopped blowing cold air. I turned it off and on again and it started working. When I got to work, I googled it and came across this thread. I have a 2013 with 192,000 miles and haven't had A/C problems yet...knock on wood.

After reading through this thread, I'm thinking of trying to take out the sensor and clean and test it (and reinstall tightly assuming it tests well) prior to going further down the rabbit hole. Based on this image that OP provided:



...would it be safe to assume that I can use some 12 gauge wire with alligator clips on one end (clamped to the bolts on the battery cable ends) and female spade connectors that would fit snug over the terminals on the switch on the other end? And have an in-line fuse on the positive wire as a precaution? What amp fuse should I use? 15A?

I haven't done this kind of electrical diagnosis and don't wanna eff it up lol. Thank you!