A/C light blinking

Twice now the light on the a/c button has started blinking, accompanying warm air blowing from the vents. Turning it off and back on makes it start cooling again, so I don't think it's a compressor problem.

Reading around a bit it seem this can be caused by a number of things the most likely seeming to be the compressor clutch relay right now. Since I understand it's not very expensive if you get it from a third party I want to try this first.

Does anyone know where in the engine compartment the relay is located? I mean EXACTLY the location if it's in a fuse/relay box?

 

In the fuse box in the engine bay (pic below). Second row from the right midway down is the magnetic clutch relay (MG CLT).

 

Thanks a lot! I stared at that for 5 min's, but it might well have been forever and still not be able to make 'MG CLT' be the compressor relay!

Magnetic Clutch...so obvious now..

 

To follow up...I couldn't find a replacement relay at pepboys or autozone...and I'm not ready to pay the $90 I hear Toyota is charging for one SOOOOooo...

I swapped the TOWING TAIL lights relay with it since I'm not towing anything right now. A/C works just fine, but it had only done the b blinking thing twice before so I suppose I'll never know for certain if that was it.

But...for anyone who'd be interested...this relay (the A/C clutch control relay, part no

$35 90987-02028 Relay

90987-02028) is a REAL common problem for Toyota's. For some reason Toyota dealers want to charge heinous price for it, and it's just a SPST 12 volt relay using industry standard pin-outs and form. Mazda sells one that works just fine...their p/no is B115. If I can't find one for the normal price of $15 or so I'll be looking for a Mazda dealer.

 

Good to know. Thanks for the heads up on those p/n's.

 

Thepartsbin.com has a relay referred to as "AC fan clutch relay" for 17.95 ea. Their part number is W0133-1762256. its a Denso relay.

 

This has happened to me a couple times as well. Dumb question how would replacing that fuse box fix it??? The fuse isn't burnt lol

 

Yep, all it takes is a google search and you'll see the problem has been around for a very long time over all their models. Sometimes the solution is to tap the relay to help free it, but it's just easier to replace it. I too, as mentioned above, have seen them online for less than $20.

 

Not everything in that fuse box is a fuse. It contains relays too. A relay is used to make a power connection based on another condition. For instance, there's a fog light relay in there. A stock Tacoma's fog lights will ONLY come on when the low beams of the headlights are on. This is where the relay comes into play. When the low beams are on, it sends power to the relay which makes a connection on the fog light wiring allowing them to come on if you've pressed the fog light switch. When the headlights are off or they're on high beams, the power is cut to the relay which disconnects the fog light wiring circuit so they can't come on.

Same situation with the compressor clutch. The wiring to engage the magnetic clutch is controlled by the relay. Otherwise, the clutch would be engaged all the time and you wouldn't want your A/C compressor running the whole time you have your truck running.

 

Relays are very versatile things! they can use a very low current signal to switch a very high current load (like a starter relay), or even detect a momentary pulse to hold an output steady with a latching relay.

SPDT relays can switch a power to either of two loads, as you relate.

Hooking two latching relays up right and you start to make logic circuits...you can make very elegant 'computers' made mostly from relays. I've worked on a couple when in the Air Force.

 

I just replaced mine. Found it at NAPA Auto Parts for $38. Kinda high but way better than the dealership. Seems to have done the trick. Thanks for the great advice.

 

Thread revival I know, but I have the same problem. I start my truck and within a few seconds the idle changes (in a bad way, like it wants to stall) for a second then goes back to normal and the a/c light starts flashing. This has happened twice in the last 2 days but not every time I start my truck. I just ordered a new relay for $26 bucks we'll see if that fixes it. Any ideas why the idle changes? I had to recharge my a/c system this past summer, I wouldn't have thought that would have anything to do with it, but the timing is unusual.

 

I had the blinking light issue and tried the relay but it didnt work. After about a year of messing around with some of the common issues I took it into an independent shop. Turned out the be the AC Amplifier assembly and the mechanic found the issue in about an hour.

 

If you recharged last summer and didn't fix the leak, you could be low on the edge of the coolant safety pressure switch which could cause the clutch to cycle.

You should get the leak fixed if you haven't already. A compressor getting ready to seize could also cause stalling.

 

I just ordered the relay and will pick it up on the weekend, but it sounds like my a/c compressor or th a/c amplifier assembly... How much is that to replace?

 

I had the same problem this last summer. Unfortunately I needed a new compressor. Because of they way our ac is designed, you also have to get a new dryer if you need a new compressor. It ran me $1,000 for everything if I remember correctly. So hopefully your issue is just the ac amplifier assembly because that'll be cheaper.

 

All AC Units are like this. You should always replace the dryer with a compressor. If the compressor goes it usually releases small metal fragments into the system which get trapped in the dryer / filter. They can plug up the system or release and get into the new compressor and cause damage. Then you would get to purchase two compressors.

 

Good to know. I must have understood or remembered it wrong.

 

If it is the compressor or assembly why does the idle drop just after i start my truck if the a/c isn't even on. I mean it's winter and I have the heat on...

 

Second Gen. trucks do not have a separate drier. It is integrated into the condenser and both replaced as a unit.

If the compressor has grenaded, you may be pulling out the evaporator from under the dash to flush/replace it, and it ain't no fun getting to it. As a preventive measure a number of manufacturers, notably GM, are recommending an in-line filter on the high side. This is interesting because our trucks use a Delphi (GM) A/C system. The filter can be placed after the condenser and before the thermal expansion valve (TXV).

Additionally, there are filtering screens available for the low side that are put in the manifold piece at the A/C compressor itself. This helps prevent the backwards flow of debris to the evaporator if the compressor grenades.

I put both on mine.

Finally, the compressor is a piece of junk Delphi. The Denso that is now available is not a true Denso but a relabeled Delphi being sold by Denso.