Toyota Nation Forum banner
1 - 20 of 25 Posts

·
Registered
Kluger (Highlander) CV - 2006 - AWD
Joined
·
144 Posts
Discussion Starter · #1 ·
I've had this problem for about 9 months now. I had the original compressor replaced but the new one seemed to be defective as the aircon would stop after 10 minutes. However I can't pinpoint the issue to the compressor being replaced as it was during winter and of course I wasn't using the aircon.

Anyway I took the car back to the aircon specialist and apparently they found some magnetic piece in the compressor wasn't doing it's job properly. They put a new compressor in but same problem. From there they replaced the relay to no avail. They apparently found another relay behind the dash and replaced that too but the problem is still there.
The aircon guys really think it's a voltage issue but are stumped.

At around the same time my alternator started making a whining noise on and off. The noise recently became permanent with research suggesting a damaged bearing. I also tested the charging rate and found it below normal but still sufficient to charge the battery. Anyway I changed the alternator today and the charging rate is back to within normal parametres.

I was rather hoping the aircon issue was due to the lower rate of charge of the alternator but it still switches off after approximately 10 minutes unless the RPM stays over 2000RPM (like on the freeway). No other electricals in the car are having any issues.

I've gone as far as I can with my limited knowledge and it seems it's time to go to an auto electrician.

Before I do I thought I would run the problem past the forum?

Thank you
 

·
Premium Member
Joined
·
2,548 Posts
Boony,
Is your climate control automatic or manual?
Will the AC engage at 2000 RPM when parked, or only on the highway under load?
Why was the original compressor replaced? Was it for the same problem, or did it fail?

I am not an AC guy, but here are a few thoughts that I hope will help you work out a data collection and diagnostic plan with the shop -
I am going to assume that the shop you took it to is competent, evacuated the system correctly, used the correct amount of compressor oil, used the correct amount of the correct refrigerant, and verified that the pressures are within spec.
If the original compressor failed, and the entire systems was not replaced / cleaned adequately, you could have debris remaining in the system which caused early failure.

For reasons I will go into below, low voltage could be a problem, If your battery is low or defective, it might take a while to charge up. What is the battery voltage with the engine idling?

The magnetic piece they replaced would be the magnetic clutch on the front of the compressor. To improve fuel economy and reduce wear, the compressor does not turn continuously with the engine like the alternator does (this is on our cars - some newer cars have an alternator clutch). The belt spins the outer pulley continuously but there is a clutch inside the pulley assembly which allows the pulley to spin without turning the compressor shaft. The clutch is engaged to spin the shaft by an electromagnet. If the voltage is low, that magnetic clutch may slip, so the statement by the AC shop is valid. But it will usually make a lot of noise.

Three things you can do pretty easily -
1) With the engine at idle, AC off, and you listening at the front of the engine, have someone turn on the AC. Can you hear the clutch engage? If not, have your helper increase engine speed to 2500 and turn the AC off and on to see if you hear the clutch.
2) Check the sight glass, located in the metal line on the fender just above the compressor area. When the clutch engages, you should see bubbles for a second, then they should clear. If you have continuous bubbles, there is a refrigerant charge problem or a compressor problem.
3) Do both fans come on when the AC is turned on? Also, check for debris, dirt, rodent nests between the radiator and condenser, etc. that might block air flow through the condenser.

You have two cases. Either the AC compressor is commanded on, and you are not getting the cooling, or the AC compressor is not being commanded on below 2000 RPM for some reason. You would need a scanner capable of accessing the AC PID's to determine if the AC clutch is being commanded on when you don't get AC, or set up your voltmeter with extension wires so that you can check the AC clutch voltage while the engine is running.

Reasons I can think of why it might not be commanded on -
1) evaporator temperature reading (real, or defective sensor or circuit)
2) line pressure reading (real, or defective sensor or circuit)
The above might be caused by defective sensors or circuit, improper charge, compressor, or expansion valve problem.

3) AC control fault. Low voltage and bad grounds can cause many mysterious issues, or the controller itself could fail.
4) Engine temperature measurement high (real, or defective sensor or circuit)

Reasons I can think of that it might be commanded on, but not be performing (not counting charge and moisture as an issue)
1) AC clutch or belt slip - this usually makes an horrific noise
2) Compressor failure
3) expansion valve problem
5) clogged condenser or inadequate air flow through condenser
4) Blend door position - I have not heard of this, but I am speculating that low voltage (power or ground) could result in a change in position, or the AC controller could be changing the position. I need to see if I can read this value with my scanner. I think I can. I will edit this and let you know after I test it this evening. EDIT: It was a little fussy and had to be restarted a couple of times, but my OBDLINK MX+ was able to access the evaporator temp, blend door position, mode door position, set temperature, and a few other AC PIDs in addition to being able to access the AC clutch command.
5) Blower motor control - same as (4)

A few other thoughts -
Even if the alternator output is good, if the grounds are not good, then there may be a voltage drop that would affect the current going through the clutch. With the engine running and AC clutch engaged, check for a voltage drop between the compressor case and battery negative.

This is a long shot, but I expect that your car is like the North American version, and the AC clutch power goes through the notorious EB2 connector located next to the battery and in front of the main relay/fuse block. EB2 is typically a problem only in corrosion country, and I don't imagine you have trouble with corrosion, but I believe salt spray and battery acid could also be a problem. I would just keep this in the back of my mind to check if I can't find anything else.

Also, I happened to listen to this today. Not the same problem, but a Toyota and may be interesting as background. 2007 Sienna 3.5 V6
 

·
Registered
Kluger (Highlander) CV - 2006 - AWD
Joined
·
144 Posts
Discussion Starter · #5 ·
Thanks both for the info. There's a bit to go through so will post back in a couple of days. Below is a bit more background.

I had the original compressor replaced as it was making a noise and I read horror stories about bits of metal going though the system. The AC was cold though. Turns out there was something loose/broken inside the compressor but there was no danger of broken bits going though the AC system. I had it replaced anyway to be safe. It was a few months after that when I noticed the issue (or it became apparent) as it was still winter.

Once the AC stops a first time then it will keep switching off even if RPM is above 2000. I write "keep switching off" as I've tried pushing the AC button to re-start but that only works for a few seconds or a couple minutes at most. The key is to keep the engine revs over 2000 from the beginning which doesn't work for stop/start city driving.

There is an switch for auto climate control. So I guess it's considered automatic climate control?

Cheers
 

·
Super Moderator
1995 T100 2WD & 1993 MR2
Joined
·
17,841 Posts
There are hi and lo pressure switches in the a/c system and as the pressures increase because of rpms and heat generated by compressing those gases the compressor will cycle automatically, better cooling and system protection. Even a low refrigerant charge will create excessive cycling.
 

·
Premium Member
Joined
·
2,548 Posts
There are hi and lo pressure switches in the a/c system and as the pressures increase because of rpms and heat generated by compressing those gases the compressor will cycle automatically, better cooling and system protection. Even a low refrigerant charge will create excessive cycling.
Agreed.
Could be the pressure switch, which is located next to the sight glass. It has a high pressure contact and a low pressure contact in series on a single input that goes into the ECM directly. The ECM can't distinguish between high and low pressure, so would turn off the compressor in either case. The pressure switch also has a contact that forces the fans to go to high speed under high pressure conditions. Therefore, fan speed may be a way to determine if the pressure switch is detecting high pressure, either real or because of a switch failure.
I assume that there is a pressure relief valve inside the compressor. That could be another suspect.
I would want to put a gauge set and a scanner on it to read pressures and PIDs at the same time to see what is happening.

Boony,
Take a look at the color of the liquid going through the sight glass. It should be yellowish clear. It should not be dark or have particles.

I just realized that they dropped the very informative service notes about the triple pressure switch in the 2007 wiring diagram, but it is still present in the 2005 wiring diagram. Another Toyota documentation error. Good thing their manufacturing quality control is better than their documentation quality control.
 

·
Registered
Joined
·
2,182 Posts
Do you have oil leaks around the compressor?

This is similar to my issue with the magnetic clutch or stator. I had momentary clutch engagement and the only way to engage it was to reset the AC and it would work for a little while up until it completely stopped working. I did remember higher RPM helped get the AC running cold.

I manually engaged the stator by giving it 12v direct. Nothing. Checked with my multimeter for resistance, nothing. Stator dead.

Went to the junk yard and took the compressor off an interchange vehicle and took the clutch and stator set $15. Replaced the stator and all was good. Did not have to replace fluids or anything else.

Your case is strange because you developed the same problem with a new compressor. I believe you have a weaken wire. I would check to see if your getting full 12v at the connector. The connector is single positive wire. One probe there and anywhere else on the chassis or block. The ground is highly reliant on a good ground connection on the block having oil and crude build up over the ground wire could be bad.

First, open the fuse box in the engine bay. Remove the AC relay. Check resistance of the main power and ground off at different spots of the engine bay(negative battery post, engine, transmission, body) I don’t know the specs for this car but i think should be 0.3-0.6 range.


Sent from my iPhone using Tapatalk
 

·
Registered
Kluger (Highlander) CV - 2006 - AWD
Joined
·
144 Posts
Discussion Starter · #10 ·
Quick update. Thank you CR and the other posters who provided some very good suggestions most of which I tried. Unfortunately I wasn't able to discover the issue and took it to an ac and electrical specialist yesterday. They couldn't either and advised to take it to Toyota to access the full suite of diagnostic software and history of any similar cases.

The specialist believes the ECU is stopping the ac compressor. He explained that there are 3 pins in the ac compressor relay with one connecting a wire to the ECU. When the ac is switched on the engine RPM is increased slightly by the ECU to prevent the engine stalling when at idle. This is managed automatically but in my case there is some sort of trigger after 10 minutes and under 2000 RPM causing the ECU to switch the ac compressor relay off. (As advised the issue doesn't occur when RPM is maintained over 2000RPM.)

I did most of the tests and checks suggested here. The system seems to be properly charged and the compressor is commanded on/off as normal in the first 10 minutes even under 2000RPM. After 10 minutes there is a drop in voltage to the ac compressor (which I'm assuming is the ECU switching the relay off) and the ac compressor stops. I can't remember the exact amount but there still is something like 9volts at the compressor even when not switched on. I don't know if that should be expected even if the ECU switches the relay off...

I'm booked into Toyota in 2 weeks and will advise the results of the test.
 

·
Premium Member
Joined
·
2,548 Posts
Boony,
Thanks for the update. I hope they can find it fast. I think the drop in voltage is a clue. According to the schematic for the 2005 and 2007 NA models, the power to the clutch through the relay is either on or off. There should not be an intermediate voltage, assuming we are talking about the MAF clutch power. Good luck.
 

·
Registered
Kluger (Highlander) CV - 2006 - AWD
Joined
·
144 Posts
Discussion Starter · #12 ·
For those who are following the thread I took my car to Toyota a couple of weeks ago for further diagnosis. The tentative verdict is a defective ac amplifier! Yup I'd never heard of one either but looking up the part it apparently manages the engine RPM when the ac compressor is commanded on. This ties in with what the ac specialist thought could be the issue with something something switching the compressor off under 2000RPM.

The price of this little gadget here is $A1510 (about US$1100)! Part #8865048101.

After picking myself off the floor I asked if a used item could be installed and if I could do it myself. Not recommended by Toyota which is what I expected but after a bit of prodding it appears to be a plug and play item and that it's located near the blower motor under the dash.

Well I've searched high and low and I just can't find this part anywhere under the dash! (I know what it looks like from looking at ones for sale online.)

I was rather hoping someone on the forum might have a photo of it's actual location?
 

·
Premium Member
Joined
·
2,548 Posts
Boony, the AC amplifier assembly, also called the AC control assembly, is connected on the back of the AC control panel, above the radio, so you probably can't see it from under the dash.
The AC control panel needs to come off. Fortunately, that is not difficult once you pry the trim panel off. However, it is easy to damage the trim piece. I use plastic trim pry bars to remove it. Actually, the best pry bar is an old Pedro's Milk Lever bicycle tire lever set that I have. It may be possible to pull it off with your fingers too. I did it once in a junkyard.

But I am a bit skeptical about the diagnosis. The amplifier board contains the higher power electronics to operate the fan and climate control doors. The ECM actually controls the AC compressor clutch. I don't see that the AC amplifier receives an engine speed signal unless it is over the network. The ECM also has the refrigerant pressure switch input. The only system monitor input that I see going directly to the AC amplifier is the evaporator temperature. The only scenario I see related to engine speed is if the evaporator temperature indication was too hot or too cold because of compressor speed. In that case the AC amplifier might tell the ECM to turn off the compressor. Otherwise, I don't see how the AC amplifier would fail and consistently tell the ECM to turn off the AC clutch at a particular RPM.

I hope they are correct with the diagnosis so you can finally get it fixed, but I would try to get a used part and install it myself to minimize the expense in case they are wrong.
One other thing to check is that both fans are working, and will go to high speed. As I recall, high speed kicks in between 203 and 208 degrees F. Toyota did the same thing with the fans that they did with the DRL's - used relays to put both fans in series for normal speed, then put them in parallel for high speed. Easiest point to force high speed is at the connector on the water temp switch on the bottom of the radiator on the passenger side. I always like to use a fused jumper to minimize the effects of mistakes. But best access is from underneath, near the fans, so care is needed to stay out of the fans.

8865048101 is apparently a Kluger part number. The US Highlander ac amplifier part number for auto climate control on a 2006 shows as 88650-48131, Olathe Toyota in the US shows that it is no longer available as a new part here.
 

·
Registered
Kluger (Highlander) CV - 2006 - AWD
Joined
·
144 Posts
Discussion Starter · #14 ·
Thanks CR! I had it in my hand all along just that the part number (or what I thought was the part number) on the circuit board was different. I had to turn it on its side to see the part number on the side of the plug! All the diagrams and photos I found showed it as somewhere else and as a fully independent unit in a box. I literally removed half my dash looking...

Yes I'm a little sceptical but all I can do is follow a process of elimination based on potential clues... especially as neither the ac specialist nor Toyota have been 100% certain thus far. I'll definitely get a used part and if that doesn't work I can resell it with a discount so not lose to much money.

For future reference to any readers; below are photos (1st and 2nd) of the ac amplifier which sits on top of the ac control assembly (4th photo) in the same box (3rd photo).

As a trial and since I had the whole thing apart, I've ordered some blue lightbulbs to replace the puke green ones which light up the aircon fascia and clock (4th photo with arrows). I was amused to find these have removeable rubber caps (last photo) which give the OEM green colour. Since removing the caps my dash lights are now vomit yellow🥴 except the 2 centre ac buttons which mysteriously remain green (maybe there are more lightbulbs underneath). I'll inspect again when I have the new light bulbs and replacement ac amplifier.

Passive circuit component Circuit component Hardware programmer Microcontroller Electronic engineering
Passive circuit component Circuit component Computer hardware Electronic engineering Electronic component
Bumper Line Automotive exterior Gas Computer hardware
Passive circuit component Circuit component Black Hardware programmer Computer data storage
Wood Rectangle Gas Flooring Gadget
 

·
Registered
Kluger (Highlander) CV - 2006 - AWD
Joined
·
144 Posts
Discussion Starter · #17 ·
Hi CR, I finally located a 2nd hand ac amplifier and am waiting for it to be delivered for testing. I'll be sure to update the forum as to the results.
 

·
Registered
Kluger (Highlander) CV - 2006 - AWD
Joined
·
144 Posts
Discussion Starter · #18 · (Edited)
Would you believe they sent me the radio/cassette unit!? Seems it was a new guy and he thought the back of the radio/cassette was also part of the ac/heater control unit. Anyway they don't have ac/heater control unit or just the ac amplifier so I'm going to tackle plan B.

This involves looking into the other possible causes suggested by CR. Initially I was a bit apprehensive but he has provided some great videos which have assisted me in understanding how ac systems work and where to look😊
 

·
Registered
Kluger (Highlander) CV - 2006 - AWD
Joined
·
144 Posts
Discussion Starter · #19 · (Edited)
So in my unending quest to solve my ac issue I'm following the kind suggestions of CR. He has helped a lot of other people with their ac issues so a big shout out to him!

Today I crawled back under the dash to locate the evaporator temperature sensor. I'm pretty sure I've eliminated various components as not being the sensor and am left with the component indicated by the red arrow. It's a round knob which jiggles slightly and has a cable going in behind it.

Try as I might I can't remove the thing. It won't twist out, screw out, or be pulled out. You can see some slight damage to the plastic where I applied a clamp for a bit more leverage. I hate plastic bits in cars as they harden over time and disintegrate so I'm wary of using to much pressure.

Does this look like the evaporator temperature sensor? The reference number on the cable doesn't produce anything with an internet search... It's sitting just behind the evaporator (assuming I've got my part names and locations right 😳). If so, what's the removal process?

Edit - found a diagram online and what I thought was the evaporator is actually the heater radiator. Same diagram shows what I believe to be the evaporator temperature sensor going into the evaporator. Now I just need to work out how to remove the thing...

Automotive design Automotive tire Automotive exterior Auto part Audio equipment
 

·
Premium Member
Joined
·
2,548 Posts
Boony,
What the arrow points to is the evaporator temp sensor on the passenger side. Since I assume yours is right hand drive, it would have the mirror image climate control case. (Actually, from the designer’s point of view, we in North America have the mirror image). The temp sensor pulls straight out with a slight twist. I will post some pictures later today.
 
1 - 20 of 25 Posts
Top