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Discussion Starter · #1 ·
This is what I have: 2006 RAV4 V6 w/180k miles. I'm original owner and have never had any AC issues. This is what I've done to date:
1. AC light started blinking and blew hot air two months ago. I added R134a (very little , maybe 3-4 oz.)a few months ago and AC worked.
2. One month ago, AC light started flashing and stopped working. I added just a little more R134a and pulled and reinstalled AC relay and AC started working.
3. Two days ago, AC light started flashing. Checked low side pressure and it was in the red. Released pressure (yeah I know) back to blue, replaced AC relay with new relay from Autozone, checked that when car is running and AC is on that there is power (13.9 V) at relay location, AC compressor front plate spins freely in each direction, all wires are in tact, when vehicle is running and AC on I checked for voltage at main plug to compressor and could not get a reading (not 100% sure if I was doing it correct). AD still does not work and AC compressor will NOT engage at all when turned on.


I'm at my wits end. I can usually diagnose and fix everything to date on the RAV4 but not now. Does anyone have any advice on what else I could check before taking it to mechanic or dealership?


Thank you,
Darren
 

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AC Post Reply

It might be that your relay is completely dead or your compressor failed.
Thanks,
rav4 1
 

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2008 RAV4 Limited V6
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Yeah, the problem is you have a small leak in the system, and when the R134 leaks out, it takes the oil with it. You replace the refrigerant, but not the oil, so the compressor doesn't get enough oil and is damaged. Typically they seize up.
 

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Discussion Starter · #4 ·
Thanks for the replies.
@JuneBug - that makes sense. The little eye glass for the AC system looks like there is no or very little oil. And I have noticed a small accumulation of oil/dirt on the rear passenger side of the engine compartment.
Do you know if the system could be refilled with oil and sealer and recharged? Since my compressor spins freely in each direction, would that indicate that it is not seized and is operable?
Thanks for the advice!
 

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Increasing the pressure in the system resolved the problem twice. Yet it would appear that the system pressure was already normal at the time (you ended up overcharging the system). I would suspect that the pressure sensor or wiring is defective, and it now requires a higher than normal pressure to satisfy the "Air Conditioning Amplifier" (ACA).

In the old days this switch was just a 2 terminal device, and you could short the 2 terminals in order to fool the system into thinking the proper pressure was available. This is a 3 terminal device, with a fixed voltage being applied across the 2 end terminals, and a varying voltage returning to the ACA from the middle pin to indicate the operating pressure. The repair manual does have a procedure for testing the sensor, which involves placing 3 1.5V dry cell batteries in series across the 2 end terminals and measuring the voltage on the center terminal. If you feel comfortable performing this test I can post the procedure.
 

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Thanks for the replies.
@JuneBug - that makes sense. The little eye glass for the AC system looks like there is no or very little oil. And I have noticed a small accumulation of oil/dirt on the rear passenger side of the engine compartment.
Do you know if the system could be refilled with oil and sealer and recharged? Since my compressor spins freely in each direction, would that indicate that it is not seized and is operable?
Thanks for the advice!
I'd say it's probably worth it to have it professionally evacuated, leak-checked and recharged. Good luck with it.
 

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Discussion Starter · #7 ·
Increasing the pressure in the system resolved the problem twice. Yet it would appear that the system pressure was already normal at the time (you ended up overcharging the system). I would suspect that the pressure sensor or wiring is defective, and it now requires a higher than normal pressure to satisfy the "Air Conditioning Amplifier" (ACA).

In the old days this switch was just a 2 terminal device, and you could short the 2 terminals in order to fool the system into thinking the proper pressure was available. This is a 3 terminal device, with a fixed voltage being applied across the 2 end terminals, and a varying voltage returning to the ACA from the middle pin to indicate the operating pressure. The repair manual does have a procedure for testing the sensor, which involves placing 3 1.5V dry cell batteries in series across the 2 end terminals and measuring the voltage on the center terminal. If you feel comfortable performing this test I can post the procedure.
Thanks for the detailed reply Rickl. I think the testing of the switch is a little beyond my abilities and patience. I'm more of a mechanical guy and stay away from electronics.
Is the AC pressure sensor something easy to replace? If it's cheap and a possible problem I could just replace it and see if the system works.
Thanks again.
 

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Is the AC pressure sensor something easy to replace? If it's cheap and a possible problem I could just replace it and see if the system works.
Thanks again.
Well, it's not difficult to replace the sensor, but all the refrigerant in the system would escape, and would need to be replaced. That is a lot of work and expense without first knowing the sensor was defective. It would be comparable to adding refrigerant to the system without first measuring the pressure to see if it needed refrigerant. (don't fix it if it ain't broke).

I guess the next easiest thing to test, is to determine if the AC clutch is getting the voltage required to engage it. There are 3 wires connected to the compressor. You can ignore the green and white wires since those are used to change the displacement of the compressor. You need to check the voltage on the blue wire (relative to ground). If there is 12v and the clutch is not being energized, then the clutch is the problem. If there is not 12v, then there could be a number of other problems with the pressure sensor being a number one suspect based on the fact that adding pressure to the system temporarily resolved the problem.

Another simple thing to do, is unplug the harness from the pressure sensor and re-seat it, in case there is some corrosion causing a bad signal.

If it was my RAV, I could also eliminate the pressure sensor as being the cause, by replacing it with 2 resistors in series. Connect each end of the resistor string to the end terminals of the sensor's harness, and the mid point of the resistor string to the middle terminal of the sensor's harness. The value of the resistors would have to be calculated carefully, but they would end up supplying the ACA with a voltage that looked like the proper pressure was available.
 

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Discussion Starter · #9 ·
Well my wife took the RAV to a local mechanic and they used a special jumper in place of the relay and also tried to send power directly to the compressor to try to get it to engage and it wouldn't. So they are saying the compressor is shot and needs to be replaced.
Thanks for the replies everyone.
 
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