Greetings. Thanks for the info on replacing the A/C blower relay. Super simple, super easy once I knew where to look. Unfortunately, after replacing the relay with a genuine OEM Denso-Toyota relay ( 90987-04002) it failed the second time I turned on the A/C. Any ideas why the relay would fail after less than 15 minutes of use?

thaks, -s

ps, I replaced the blower motor while in there, which was not so super easy or simple...and neither of the two fuses have blown either time.

 

What is the problem you are having? What are your symptoms?

Are you 100% sure the relay is your problem?

What testing did you do to confirm the relay was bad?

For what its worth, I rarely see the blower relay go bad. That doesn't mean your blower resistor isn't bad, it just isn't my first suspect.

 

Symptoms: Nothing happens when I activate the lever fan or the A/C push button switch. No power to the blower motor. No compressor clutch engaging. Nada.

The last time this happened, after checking the fuses, I replaced the relay which was making "loose parts inside" noises. Fixed it right away.

First time I needed the A/C, nothing happens when switched back on for the 2nd or 3rd time in 6 mos. Pulled the new relay, and now the new relay is making the exact same "loose parts inside' noises when I shake it next to my ear, it now sounds like the old relay, which the new relay did not make fresh out of the box. Resistor looked brand new. Replaced stiff blower and relay. Fuses behind kick panel did not blow either time.

The last time it blew it was last winter and blew about 45 minutes into a long, very chilly road trip. At the time it blew, it simply shut down with only the blower on heat. No A/C compressor in use. Rarely is. So it seems to be blower side, not compressor related. Thus the blower swap. New one did spin more easily.

The "noise" itself is very similar to a blown Edison style light bulb when you shake it and hear the loose, spring shaped filaments wiggling. Maybe a little louder/clearer, but very "thin coil type spring sound". Not a broken/loose parts rattling, or contacts shifting kind of of noise. Regardless, it does not sound right and the situation corrects itself when a "noisy relay" is replaced.

Tha is until the replacement relay starts making the same "broken spring" noise when shaken.

I have two replacement on order from Rock A, so should be able to test/replicate late next week.

I agree, relays should not fry, at least not that often. Truck rolled 250K last Fall. So just breaking in.

Thanks, it's a puzzler.

 

Sounds like the relay might be getting too hot. Bad connection somewhere along the power source?
pull out a multimeter and start testing wires for voltage and resistance

 

Thanks, I'll check it out.

 

Okay, everything checked out on my V/Ohm meter. So I cut the old relay open, and the entire insides were covered in corrosion, as if it had been filled with water. Only thing is, there are no signs of water penetration behind the kick panel, anywhere else, not on the adjacent parts, eg the MCU, the fuses... nada. How the heck does that happen? Would drilling "weep holes" make it worse, ie easier for moisture to get in?

 

The relay would fail if the draw is higher than the relay is rated for. Besides checking the incoming voltage to the relay coil, did you check the current draw using an ammeter when you turn the AC on?

 

Thanks, after digging around, and into the relay, it appears that somehow moisture is getting into and collecting inside the relay housing and corroding the contacts, and everything else. So it's probably a bad seal between the kick-panel assembly and the exterior vents. At least I hope that this is just another call for the RTV. Or repositioning the relay so that water cannot run down the harness and collect inside the cover. Of course it was designed so that if any water does run down the harness and leak in, the contacts get wet first...

 

If you're getting water in there, it would be best to figure out why instead of relocating the relay. That water will end up causing other electrical issues over time. Besides the windshield seal or vent, this person found the leak coming from the fender: https://www.yotatech.com/forums/f116...coming-139455/.

 

Awesome, thanks. I was not having any luck finding leaks with the garden hose up top. I did notice when I was changing out the tie rod ends at ball-joints when she rolled 250K, that the skirting around the top of that plastic fender "lining" was missing. That just might be the source. Thanks!

Much appreciated, -s