New member, help with Toyota Hiace AC

[Billyb]

Hi all, new member from the UK.

Ive just bought a UK spec 2009 Toyota Hiace 'Powervan' with a 2KD-FTV motor, pic attached. It has factory AC (rare for these vans), but sadly it is not working.

Ive done a bit of fault finding, but am a bit confused with a few areas. I was hoping someone could please help me!

The AC system is R134a. Pressing the AC switch with the fan running illuminates the switch lamp, but the compressor does not engage. There are 3 relevant fuses, all are good. However what has tripped me up is that there is no relay for the clutch! There are 3 relay / fuse boxes, none detail one. To make sure there is no a differently labelled relay which controls the clutch I have pulled and tested every relay on the van, all are working fine (fully tested each on a bench with remote 12v supply). I disconnected and checked for continuity across the pressure switch, which there was. Interestingly when I tried to operate the AC with the switch disconnected, the AC lamp flashed. This told me there was some intelligence or logic to the system, so a bit of research led me to identify and locate the AC amplifier. I did not know such a thing existed before. A visual inspection of the board gave the all clear. I also continuity tested every wire I could trace, switch to amp, fuse to amp and switch, amp to compressor clutch etc. I sourced a spare amp, same Denso part number from another Toyota breaker, no change to fault. This is not to say the amp is still not faulty, but my gut tells me it is not that.

Questions:
Does the amp replace the need for a relay?
The compressor has a 3 pin connector. 1 pin is the clutch live feed. What are the other 2 wires for?
Is it ok to just false feed the clutch to check it engages? I personally think this is the fault.
Can a Denso clutch be replaced on its own without removing or disturbing the rest of the compressor? I ask this as the compressor is very challenging to get to, owing to the short bonnet.

Sorry for all the detail, I hope I can get this sorted. Thanks for reading if you got this far.

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[Billyb]

I was going to add, I have not tested any pressures yet as I dont have a manifold. I am considering buying one, however my gut feel is that the problem is electrical and not due to a low refrigerant level. Only when I have proved the sensors and clutch to be ok will I get a manifold.

[JohnHere]

Welcome.

First and foremost, you'll need to get the correct, exact weighed charge in the system before testing the pressures and diagnosing further. Otherwise, the pressures are meaningless.

Also, the pressures alone won't tell you how much refrigerant is in the system now and how much to add.

Lastly, it's not advisable to "jump" the compressor. If the system is low on refrigerant, which in this instance it very well might be, force-running the compressor will starve it for oil, which will destroy it quickly.

[tbirdtbird]

Welcome.
Please be advised that links to eBay are not permitted.
Please remove the link

[JohnHere]

(Moderator edited: Removed the link, graphic, and references.)

I was going to add, I have not tested any pressures yet as I dont have a manifold. I am considering buying one, however my gut feel is that the problem is electrical and not due to a low refrigerant level. Only when I have proved the sensors and clutch to be ok will I get a manifold.

It's not known yet whether the problem is due to low refrigerant, something electrical, a mechanical issue, or a combination of issues.

Your van is about 13 years old. It's very likely and fairly typical that normal seasonal losses—or leakage at one or more areas—have depleted the refrigerant to a point where the compressor no longer engages. You'll need to take the vehicle to a competent A/C shop having the proper tools to recover the refrigerant that's in the system now, evacuate, and re-charge it to the specifications as shown on the under-hood decal. Only then can diagnosis continue.

Does this vehicle have front and rear A/C or front only?

[JohnHere]

Questions:
Does the amp replace the need for a relay?
The compressor has a 3 pin connector. 1 pin is the clutch live feed. What are the other 2 wires for?
Is it ok to just false feed the clutch to check it engages? I personally think this is the fault.
Can a Denso clutch be replaced on its own without removing or disturbing the rest of the compressor? I ask this as the compressor is very challenging to get to, owing to the short bonnet.

—No. On a Toyota, if it has a clutch, there's still a relay someplace.
—One of the wires in question is a ground, and the other wire goes to either a control valve or an RPM sensor located somewhere on the compressor (usually on the bottom) that feeds a reference voltage to the PCM.
—No. Don't "jump" the clutch for the reason previously mentioned.
—Yes. The Denso clutch can be replaced without removing the compressor by taking out the center bolt (10mm hex head), pulling off the outer clutch plate (don't lose the shims), removing the inner snap ring, and pulling the coil, pulley, and bearing. But before doing all that, check the clutch gap, which should be about 0.020" (0.5mm) or approximately the thickness of a business card. Add or remove shims accordingly.

[DetroitAC]

I would suggest getting the correct R134a charge in your van before any troubleshooting. It has controls and algorithms to prevent the compressor from engaging if your charge is low. These could be working as intended, given the age of your van, probably due for a recharge.

One wire is clutch hot, the other two are likely to the control valve on the back of the compressor, she's an electronically controlled variable, I think.

You can check continuity and resistance of the clutch coil, one lead to the connector, other lead to the chassis ground. You can also check resistance of the control valve from one of the wires to the other, it's just a coil also. Clutch coil in the ballpark of 3 Ohms, control valve in the ballpark of 12 Ohms.

[Billyb]

Thanks very much for all the replies people. I'll get it booked in somewhere to get the refrigerant evacuated and recharged as a first port of call I think, then will report back.

The van has AC in the front cab only. It is just a panel van so nothing in the rear. There is a steel bulkhead seperating the two so I was hoping the small cabin space would make the AC pretty effective. Its obviously of more value for dehumidifying / demisting in the UK as opposed to cooling, but it is still worth sorting properly.

Interesting to know there is still a relay somewhere. I'm dumbfounded as to where, but will keep looking. So 100% not integrated with the amplifier?

PS sorry for the ebay link also, I see an admin removed it for me, thanks. Warning heeded.

[JohnHere]

I'll get it booked in somewhere to get the refrigerant evacuated and recharged as a first port of call I think, then will report back.

I believe that's your best place to start. If luck is with you, recovery, evacuation, and bringing the refrigerant amount up to specs is essentially all you'll have to do. However, while the vehicle is in the shop, I also recommend having them scan it for codes even if the Check Engine light is off, and sweeping the system with an electronic "sniffer" to ensure there are no leaks.

The van has AC in the front cab only. It is just a panel van so nothing in the rear. There is a steel bulkhead seperating the two so I was hoping the small cabin space would make the AC pretty effective. Its obviously of more value for dehumidifying / demisting in the UK as opposed to cooling, but it is still worth sorting properly.

I agree, not only for de-humidifying/de-misting year round, but also for those rare summer days when driving without A/C will have you feeling rather warm and uncomfortable.

Interesting to know there is still a relay somewhere. I'm dumbfounded as to where, but will keep looking. So 100% not integrated with the amplifier?

According to the electrical diagrams I have for your vehicle, the A/C Relay isn't integrated with the A/C Amplifier. As you already know, the Amplifier is located next to the right-hand center vent up inside the dash.

The Relay Box, which contains fuses as well as relays, is located in the center of the passenger-side dash just above the lower edge of the dash panel and slightly behind it. The fuse for the A/C system is Number 6 (7,5 amps), and the relay for the A/C compressor clutch (called "MG CLT," or Magnetic Clutch) is Number R8.

These locations presume that your diesel minivan is UK-spec right-hand drive.

If the fuse and relay test good, then the problem is most likely a low refrigerant charge.

PS sorry for the ebay link also, I see an admin removed it for me, thanks.

No apology necessary. You didn't know. I took care of the edits for you

[Billyb]

Thanks for the reply and for all the pointers. Fingers crossed it is just low gas as you say. We are having one or two of those rare summer days at the present moment, so not the best timing!

Could I please have the relevant extracts of the electrical diagrams that you have? I am yet to find a good online manual for van.

I saw mention of the MG-CLT relay you mention on a Toyota forum, but my van does not make mention of it, nor does the owners manual. There is a small fuse box in the drivers side footwell (right of the van looking forward, RHD obviously), the AC fuse in #15. There is a small bank of relays adjacent to this, none are labelled and there is no provision for a cover. because I had no way in identifying each I have removed and tested the lot (continuity of coil and contacts, coil operation, and contact resistance when coil energised etc). There are no relays missing, ie no blank spaces. I hope one of these is the MG-CLT relay, if so, I'm confident it works. All fuses good also, tested with a Fluke multimeter, not just an eyeball test. It had crossed my mind that the AC install was done after the factory build, hence a reason for the relay to not be labelled, but I don't believe that is the case, the rest of the install looks to be complete and original.


Another couple of questions if I may;
I also have a UK spec but US built '97 Honda Accord Aerodeck, what you might know as an Accord US Wagon, with the F22B engine and factory AC. The AC has never been serviced, but still works very well even after 25 years. Ive owned it for 14 years and use the AC at least twice a week. The first owner (I'm only the 2nd) used it regularly also, he was a family friend and cared for it diligently. It is a R134a system also. Because of my experience of this and other older Hondas I had assumed that if the AC is used regularly, it should maintain the refrigerant and not loose charge. Is this not the case? Ie is it abnormal for my Honda to still be working this well at this age?
My experience here also is what made me look at the electrical aspect of the Toyota AC first before checking the gas.
Are Toyota's' systems more prone to leakage?
Is there a significant range different manufacturers AC configurations, ie does the low refrigerant / pressure threshold differ between manufacturers? Would the Honda still be working because the limits are more generous (if they even exist), with the Toyota limits being less forgiving?


PS I tried adding a few pics to this post, but they keep failing, despite being under 256kb?

PPS thanks for your time in reading and answering my many questions! You might have guessed Im an Engineer by trade, and am always looking to learn more.