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A/C control issues after major a/c service

agb104983 on Fri August 07, 2015 11:59 PM User is offline

Year: 2008
Make: Toyota
Model: 4Runner Limited
Engine Size: V8 4.7L
Country of Origin: United States

I have a 2008 4Runner Limited V8 4x4. About two weeks ago my a/c suddenly went from working fine with no issues to making a loud buzzing sound from the engine bay when the a/c tried to engage before turning off after a second and showing a flashing light on the a/c switch showing a fault. It appeared that the compressor had seized up and repair shop #1 checked it out quickly and agreed. I ended up picking repair shop #2 to do the repairs because they have done work for my boss for many years and their price was equal or less than shop #1.

Shop #2 orders an A/c kit for my 4Runner and does the compressor/clutch unit, the condenser/dryer unit, flushes and recharges the system. When they go to test it out and engage the A/c system, nothing engages and after a couple seconds the A/C light changes from a solid to blinking, indicating a fault. They evidently did a bunch or diagnostic work and isolated it down to the A/C amplifier(aka computer, aka module). I don't know if they tested each individual sensor that feeds into the amplifier but they seemed pretty sure it was the amplifier. I wasn't going to pay them to replace what appears to just be a box under the dash and so i picked it up and paid them for the parts/labor already done. They showed me the amplifier before they put the dash back together and showed how it didn't work normally. Then they put either power or ground to the yellow/brown wire in the a/c amp wiring harness and when they did that, it engaged and the ac worked fine. I think they were basically bypassing the amp.

Now, I have found a secondhand a/c amplifier for around $100, which is less than the 300-500 that toyota dealers and parts retailers want. If its just the a/c amplifier, it should be a decently simple job of getting into the dash and switching out the box. My concern is that as of a day before taking it in, it appeared that the computer was still working fine because when I tried to engage the A/c, you could hear the clutch/compressor making that loud buzzing sound in the engine bay. I guess it could have burned out since then or if there is a relay inside the amplifier, that could have burned. Otherwise, I'm concerned that I'll get the used a/c amp and find out that it still doesn't work.

Any ideas? I have seen page posted from a 89 4Runner service manual where it showed how to test the signals at the a/c amp wiring harness plug in order to ensure that all the signals were correct. Does anyone have something similar for my unit? I know they used different A/c amps for the various trims and years. My OEM Desno unit number ends with 260. Just to clarify again, this picture below is NOT FOR MY 4RUNNER but just an example of what I'm looking for along with any advice you might have. Here is an example of the type of diagram I'm looking for that I found online from a 89 4runner:

Thank you for any help you can give me.

Edited: Sat August 08, 2015 at 12:05 AM by agb104983

AC_Doc on Sat August 08, 2015 1:43 AM User is offline

My records indicate the 2008 Toyota 4Runners don't have an A/C Amplifier. That might be why its hard to find.

Sometimes you must accept things at faith value!

agb104983 on Sat August 08, 2015 9:39 AM User is offline

It definitely has one. I saw it when the shop showed it to me and I've called the dealer to price it new. Its a Denso made toyota part and the model number is 88650-35260.

AC_Doc on Sat August 08, 2015 12:41 PM User is offline

OK... Deeper look at the specs.
Listed as AC Control System...

Is this the connector you have??

Sometimes you must accept things at faith value!

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