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Discussion Starter · #1 ·
The air conditioning on my 2016 with roughly 50k miles has stopped working. It's hard to say if it was a gradual thing or stopped over night given that it has been cold here. The compressor does not appear to be engaging at all....no change in RPM when the ac button is pressed. There does not appear to be any damage to the evaporator core which would cause a leak. Does anyone know what fuses/relays I should check and where they are located? The abbreviations in the panels under the hood and dash are not clearly pointing me to the a/c. Any other suggestions in diagnosing the problem would be great. Thanks!
 

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01 Avalon XL, 03 Avalon XL
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First, if you're going on fuse box labels, it sounds as though you might want to d/l an owner's manual:
Toyota Owners site
Click on "Join now," enter VIN
My Vehicle: Car original specs and service history (dealer service done)
Parts & Services: Maintenance Schedule
Resources: Manuals and Recalls

You can tell positively if the compressor is not running by observing it. There's what appears to be a disk in the center of the spinning outer bit, the portion that's driven by the belt and turns all the time. When the compressor is off, the disk is stationary. When it kicks in, that disk should click and start turning.

If it's like the Denso system on my Avalon, the Defrost setting is a second circuit to the a/c compressor. Check to see if the compressor kicks in when somebody selects Defrost on the dash. If so, your a/c control might be unhappy.

I'm pretty sure the next step for diagnosis is to check the system pressure. You can do that yourself, but it requires a gauge manifold (Harbor Freight used to have a fairly inexpensive set). There are lots of youTube videos on how to diagnose with an a/c manifold, and what the low and high pressures should be.
 

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Discussion Starter · #4 ·
I have a copy of the owners manual, but could not locate any additional information in it regarding the fuses/relays. The only information inside the cover of the under hood fuse panel that is close to cj1's suggestion is labeled "M G C", and there is no relay in that position.

After observing the compressor as recommended, there does not appear to be a stationary part as described. Everything seems to be spinning regardless of the a/c button position. No change when using the defrost functions either. So, either the compressor is somehow stuck on (and not cooling) or the compressor is not the same as described.

Either way, I appreciate the suggestions and am open to more. I will see if I can get my hands on a set of gauges and check the pressures as recommended as well.

Thanks!
 

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Oops, bad of me not to notice it's a 2016, just a baby. You might have a type that I know nothing about, sorry. It's odd that the manual is incomplete around fuses, functions, and locations.

Pressure testing is likely the best mode of diagnosis. If the pressures are where they should be, then you begin tracking down electrical issues.
 

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マズダスピード3
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Op, is there any kind of air flow when you turn on the AC?

Engage the AC and feel the low side pipe to see if there is a temp change and cold to touch.

Is the blower motor spinning?
 

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Yes. Blower works normally at any speed setting. I will check the pipe temp as you suggest. Thanks.
if it isn't a relay or a fuse, AC failure can be that the clutch coil is broken, which won't engage your AC. you can see the wire in the top of the diagram, its the coil inside the AC clutch. or your system has lost coolant and a pressure switch will stop the compressor from kicking in, or the pressure switch is bad.
296042
 

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Have you tried the heater yet? If the heater works, but the AC clutch does engage, you likely have a clog in either the heater core or the evaporator.
 

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The 2016 uses a variable displacement compressor, there is no magnetic clutch. You will never hear the clicking sound of the old magnetic clutches. Visually it will appear that the compressor is running because it's always spinning there is no clutch that cycles. There are valves in the compressor that controls output and pressures and it depends on the pressure in the system and several sensors monitored by the HVAC module to determine output..

As recommended earlier you can feel the low pressure line (the big one) and feel if it's cold and see if the cooling fan is running. If the line is not cold but the fan is running it's a indication that the command to turn on the A/C has been received. The electrical side should be OK if this is the situation but there is a problem mechanically which could be a number of things. The best thing to do is to take it to an expert that can access the HVAC module to scan for fault codes and do a proper diagnosis.
 

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The 2016 uses a variable displacement compressor, there is no magnetic clutch. You will never hear the clicking sound of the old magnetic clutches. Visually it will appear that the compressor is running because it's always spinning there is no clutch that cycles. There are valves in the compressor that controls output and pressures and it depends on the pressure in the system and several sensors monitored by the HVAC module to determine output..

As recommended earlier you can feel the low pressure line (the big one) and feel if it's cold and see if the cooling fan is running. If the line is not cold but the fan is running it's a indication that the command to turn on the A/C has been received. The electrical side should be OK if this is the situation but there is a problem mechanically which could be a number of things. The best thing to do is to take it to an expert that can access the HVAC module to scan for fault codes and do a proper diagnosis.
well i honestly thought the diagram i posted was from the 2016.. oh google failed me.. again.. i went out and looked at my 2016 and it totally isn't what i posted. thanks for the feedback and information
 

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Discussion Starter · #12 ·
To answer some questions....The heat works fine. No issues there that I am aware of. The low pressure line does not get cold and the cooling fan is not running when the a/c button is pushed. Any other things to check is appreciated. Thanks.
 

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Either you have an internal leak or the AC compressor is failing. It is a premature failure with only being 4 years old.

I am not 100% sure, but I think AutoZone or o Reilly's rents ac gauges to measure the pressure.
 

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Check fuses and relays. If the cooling fan doesn’t come in it’s a sign of a electrical problem. Even if the compressor was shot the cooling fan should come on anytime the A/C is running.
 

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+1 to take it in to the dealer or a trusted mechanic for proper diagnosis. These are not systems that a shade tree mechanic can work on easily without the proper equipment.
 
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