A/C Light Blinking Troubleshooting Guide

Thank you for the info. It seems the symptoms for this sensor failing is the AC light blinking after 5-10 seconds? Mine only seems to blink after about 20-30 minutes of driving. And even that isn't consistent. As I drove several days with no issues.

 

Mine was always sporadic, could be after 20-30 minutes, or sometimes not at all. I replaced the or fixed 4 different items before trying this and it being fixed.

 

great info in here guys..

question.. to the guys who have had their system stop blowing cool air after 5 seconds, and have had luck with either the replacement of the Compressor Pickup Sensor or the A/C Compressor Control Relay....
Did you guys experience the whining too?


that threw me off once I heard that.. Seems like my problem is intermittent.. 8 out of every 10 times I turn my AC on, I hear the whine for a few seconds, and after 5-10 seconds I get the blink and the whine stops..

And I first thought it'd be the compressor.. but now im curious.

Thoughts?

 

Here how my sensor looked. No wonder it wasn't reading, just dangling there. Dealer didn't see it when I paid them to check my system. Thanks for making this thread.

 

Hopefully this isn't off topic, but what if the AC stopped working but I'm NOT having a blinking light??? Compressor clutch is engaging and staying engaged but the air is just barely cooled from ambient. Thoughts?? Thanks

 

Trying to cure my blinking light also .My light is on solid (no compressor spin )for about 3 seconds then blinks. I can put a couple jumpers in to replace the new relay and make the compressor run fine. It also has a good charge of 134, new pressure switch . I just tested the compressor speed sensor and get 9V doing it with the test procedure shown in this thread. I am guessing then that 2-3v is good and mine is bad at 9 if I am understanding it correctly ?

EDIT: No One Knows? Guess its going to be another inexperienced guess , ordered
88346-04010

 

And 88346-04010 had no effect on Blinking light either

 

Replaced AC amp , nice cold air now . Seems a number of issues can give very similar results. It became easier to figure out when I finally got in my head that every connection is hot all of the time and its the ground that gets connected that turns things on and off. Im kind of used to following hot wires not grounds so much. White wires with black stripe seems to be the preferred color for most of the grounds on this truck. About a million in your rt front kick panel. I hate electrical issues.

 

Did you figure this out? I too just encountered a whining today and the blinking light.

 

I had some loud whining noises a month ago, blinking light etal. I took it to a local dealer (not Toyota) and after they did what they did, the compressor was replaced. The system ran great, good and cold. However, after a few drives, I would get the blinking light. Sometimes, when I turned the system off and back on, it would work fine. Sometimes it wouldn't. Sometimes it took me having it off for longer time periods before I could get it to work. Sometimes I would park it, do my chore and come back and all would be well. I can't say it's rpm or throttle related although at first it seemed. I would try to induce the blinking light with higher/lower rpms, different gears and I couldn't reproduce it. The dealer asked me to see if this forum might come up with an answer before they started troubleshooting it all again.

I've read this thread and took notes on various suggestions. However, with this compressor being 'new' and then these issues, is there something specific I should consider and share with them. Thanks a bunch, this forum has been most helpful to me over the years despite me not posting much. It's a great source of help and info. My Tacoma is a 2006. Thanks.

 

That's a new one, is the dealer new at AC work? lol
Was anything replaced other than the compressor?
Can the dealer give you the hi/low pressures, the ambient and vent temps?
The more info given, the less guessing given.
Might be the compressor sensor, or the AC amplifier. Might not.

 

Thanks Curt. The dealer is a GM dealer, been around for decades, the service manager and I go back a bit. I was only charged for the compressor and labor, the invoice didn't show anything else mechanically substantial on it. I can check with them for the high/low pressure readings (if they recall or recorded them). I can say I keep a thermometer in my inside ducts and at the coldest inside recirc I get 41*-43* (a degree or so higher with outside air) when ambient is from ~70* to roughly 85*. These are as good as ever, even when new back in '06. Thanks again, I surely appreciate your input.

Tom.

 

Your vent temps are right on. Sounds like your dealer is good, but it depends on the tech doing the work. Newer vehicles are a pain to troubleshoot.
If the condenser wasn't replaced, there may be a restriction. The condenser has the filter drier built in. (stupid move from engineers)
Get more info if you can, or have them hook up gauges again. I would think that if they are asking an internet forum for help, it would be at no charge to you.

 

sub'd. Need to figure mine out in the very near future.

 

Had this issue, replaced the sensor and relay only to fix the problem and have it start again. Solved at the mechanic, bad wiring to the compressor and another relay. It was arcing/shorting and that was causing the relay to burn out.

 

so many things can cause the blinking light. When ya first start searching its like oh great easy fix new relay , nope then speed sensor nope than a new pressure switch then all said and done a new AC Amplifier.

 

I finally was able to take a better look at mine. I just went ahead and swapped out the relay. Now, at idle the AC light stays on no cold air. When I increase the RPMs 20-30k ... I hear a brief whine and when the noise stops I see the light start blinking again.

 

In my 2005 tundra the speed sensor in different. It bolts in side the compressor. I have no power to the sensor or clutch. I have replace compressor, expansion block, receiver dryer and evap core. Light still blinks. There is no relay either. Pooling my hair out.

 

You need a Factory Service Manual (FSM) if you are going to take on repairs/troubleshooting. Absolutely there should be a relay. Chase all the wiring from the compressor back to the firewall and make sure its not damaged. Do the same on the other side of the firewall in the foot/wheel well. Pray to your gods its not behind the dash.