2007 Tacoma A/C Blinking Light

Do these tests and diagrams also work for a 2013 V6? I’m having similar issues. I’ve swapped relays, and tested the flow sensor, still looking for things to test. Thank you in advance

Edit. My ac works sometimes, and other times i get the blinking light. Getting the blinker more frequently now. (Why i tested the flow sensor.) The flow sensor readings were bouncing all over the place with a magnet near the sensor but with the magnet touching the sensor the readings got stable and it seems like that sensor is ok. 2.4v - decrease with one side of my magnet, increased with the other. I don’t have a magnet that’s marked north and south so I’m assuming the sensor was reacting properly but not 100% confidence

 

Wiring is slightly different on a 13 but the MG CLT Relay location and pinout is the same.

Would take some testing to find out the cause but one quick test you could do is to swap the MG CLT Relay for a known good one, if that's not it then you have to test when the problem is occurring.

What I would likely do if one of these came into the shop with your complaint is put a test light on the power wire to the A/C clutch and put an oscilloscope on the Lock Sensor wire and see what I lose when the problem occurs.
If I kept power but the clutch kicks out then I have a bad clutch, if the clutch stays engaged but I lose the Lock Sensor signal then I probably have a bad lock sensor.

 

Is Lock Sensor another term for the compressor pickup sensor? Part Number 88346-04010? Screwed to the side of the compressor with 1 screw?

If so, since i couldn’t possibly test it in the way you described, maybe it’s time for me to throw this part at it and cross my fingers.

Well, i could do the first test, but i don’t have access to an oscilloscope.

Which is more likely to fail, the mag clutch? Or the sensor? Or is it a toss up?

 

Yes.

I hate throwing parts unless I can verify they are bad, both the clutch and Lock Sensor can and do fail. I have also seen the relays fail, the problem with intermittent issues is you need your test equipment connected when the problem occurs to effectively diagnose it.
I guess the Lock Sensor and MG CLT Relay would be cheaper and easier to replace than the clutch but I'm not a fan of the parts cannon.

I wish there was a better way to check the lock sensor signal but it's such a tiny signal that you can only see it on a scope.

It will blink a 150mA test light dimly if I backprobe the wire behind the glovebox but I'm not sure if that's a valid test or not.

 

Thank you for your help. I, too, hate the parts cannon, but at this point i feel like that’s where i am. My local Toyota shop is kind of a joke. I’ve had nothing but problems with them.

Some days the a/c will work flawlessly, and then others it’s almost impossible to keep it running. Then there are days when we can keep it running for a few minutes at a time and when the light begins blinking turning it off then on will make it run for another few minutes. It does seem like it’s more likely to start blinking at higher engine rpms. That kind of wants to point me at the Lock sensor, but then possibly the amplifier. Although, sitting here thinking about it, a slipping mag clutch might trigger it as well?

Shop rates here (for a lousy shop) are running around $150 an hour, so that makes shooting parts at it a little more appealing to me.

If i was going to connect a test light to the clutch power, is that the short wire coming out of the lock sensor harness? Or is there a better place to hook to that circuit?

i really appreciate all your help! As well as the wiring diagram!

 

Yea that's the sad part of the industry, it's really hard to find a good shop that doesn't do hack work and does actual diagnostics. It seems nowadays everyone just want's to make a buck and not many people take pride in their work anymore.

I suppose the belt could be slipping, have you verified the tensioner is keeping it tight?

I would be nice if there was a relay in the box that is the same as the MG CLT Relay, there's some with the same pinout but I believe the MG CLT Relay is diode suppressed to prevent voltage spikes where normal relays aren't.

The A/C Amplifier almost never fails, I've only ever seen one that was bad.

The Violet wire is the control wire going to the compressor clutch, the easiest place to backprobe it would be at connector EA1 Pin 3 (Violet) in the Engine Room Fuse Box.

 

Hello nice to see how helpful community is. I have 2013 Tacoma that I performed all of the mentioned test. Passed all test.
Pin 1 flashes until ac light starts blinking then turns off. Was wonder what I should try next.

 

Does the compressor engage momentarily until the light starts blinking or does it not come on at all?

 

Yes it does

 

Have you verified the rubber hasn't separated on the clutch?

 

Yes. I just replaced with a new compressor a couple weeks ago.

 

2009 Tacoma, blinking A/C, can hear clutch engage/disengage with oem relay installed, but center part doesn't spin (but moves a tiny bit)

Jumping the high side of MG CLT relay with series 6A fuse and switch, I can engage/disengage the clutch with my switch, and centre part spins when activated, but seemingly no cold air. No noises from belt, although when the A/C first stopped working I was hearing some whining momentarily when trying the A/C, which failed during HWY driving on a very hot day.

Mechanic checked the refrigerant and was ok, so that's a bit puzzling, figured with the clutch jumped and spinning, compressor should be working (even if a/c light blinking)

Was thinking of throwing compressor speed sensor at it, but would maybe like to back probe the AC amplifier or somewhere else to see if I can see the sensor signal. The truck just got Krowned so I want to avoid working under it.

Anyone know which wire to check and the possible locations to check it? I have a portable scope too

 

Is the whole clutch turning including the center part circled in red or just the outer part circled in blue??




You can check the Lock Sensor Signal at Connector IH1 Pin 10 (Red/White) behind the glovebox.

 

It looks like the inner (red) stops and starts when I switch it manually with my fused/switch. With the regular relay installed it just moves almost unnoticeably.

 

I was just trying to make sure the clutch hasn't separated, not uncommon for the rubber damper between the red and blue parts to fail and slip.

Have you tried a different relay?

 

The clutch doesn't look like it's in the best condition, but it seems to work. I had swapped the horn and MG CLT, same result.
Thanks so much for the nice picture of the connector, that's exactly what I was looking for .
I'm going to try putting my scope on that next time I get a chance, will update here. I presume I'm looking for a cyclical signal there, I picture the lock (hall effect) sensor getting triggered as the compressor spins (guessing there's a magnet inside somewhere on a rotating part.

 

Yea it's kind of an odd signal for a hall effect sensor, it jumps up to 12v when first turned on and settles down to a very small signal of only about 300mV peak to peak.

I posted a Pico capture in post #24

 

Incidentally are there any other sensors going into that connector I can check while I'm there? And expected voltages?

 

I mean nothing that has to do with the HVAC system.

This is my breakdown for an 06, I know 13 won't have the Vehicle Speed Sensor wires but not sure about the rest.

 

Back probed the connector with the lock sensor signal earlier while jumping the clutch: I couldn't get as clean looking display as your post #24 on my OWON portable scope but I was seeing a very small varying voltage that was ~2.64V. It was number displayed on the bottom right of my scope after a few seconds (trigger voltage I believe), and it corresponded to where the signal was.

With the OEM relay back in, and trying to engage A/C, there didn't appear to be any signal. One thing I forgot to observe is if the signal appeared momentarily or not. I suspect not since I never see the inner clutch spin.

Still puzzled by why I'm not getting cold air while jumping the clutch, compressor is seemingly rotating internally based on the signal. What else needs to happen for the A/C to actually cool? Now I'm beginning to doubt if the system is in fact charged up enough, and perhaps it's flashing due to a pressure sensor reading low? When it failed originally it was pretty instaneous, cooling was good until all of sudden it wasn't