Need help with AC

[T4Rscott]

Hi all,

As some of you may know, I have been battling off and on, an AC that won’t engage the clutch at idle.

I have done/ replaced the following:

Condenser
Receiver/ dryer
Pressure switch
Evaporator
Thermistor
Changed TPS
Changed IAC
Swapped compressor/tested clutch
Swapped ECM
Swapped amplifier
Continuity/voltage on harness.
Checked and swapped AC switch

So I believe there’s a wire not getting signal. I need someone to explain what wire signals the idle, and what should I see for voltages.

I know I’m getting close. I will be going through the grounds and checking the fan clutch.

Thanks

 

[96RedRunner]

The AC section of FSM has 103 pages for troubleshooting, 3-4 wiring diagrams.

 

[gamefreakgc]

I have never been able to understand the A/C signals used by the ECU to either increase the idle speed or when it engages/disengages the clutch. Mine has a idle issue where it sometimes doesn't idle up. Sorry no help here but interested in what the solution might be as it may help my situation as well.

I do know that the clutch signal wire is a single wire that grounds on the compressor and essentially the engine block itself. I'm not sure why Toyota did this but if your engine isn't grounded well off the engine it could cause some wonky issues.

 

[brillo_76]

I have never been able to understand the A/C signals used by the ECU to either increase the idle speed or when it engages/disengages the clutch. Mine has a idle issue where it sometimes doesn't idle up. Sorry no help here but interested in what the solution might be as it may help my situation as well.

I do know that the clutch signal wire is a single wire that grounds on the compressor and essentially the engine block itself. I'm not sure why Toyota did this but if your engine isn't grounded well off the engine it could cause some wonky issues.

That makes sense. Maybe your compressor is not getting good ground. Possibly.

Sent from my SM-A536V using Tapatalk

 

[T4Rscott]

That makes sense. Maybe your compressor is not getting good ground. Possibly.

Sent from my SM-A536V using Tapatalk

That’s what I’m thinking.
I’m going to run a ground to the engine to frame cable

 

[brillo_76]

That’s what I’m thinking.

I’m going to run a ground to the engine to frame cable

Your entire ac issue is baffling.. Been scratching the head the entire time on this one.

Sent from my SM-A536V using Tapatalk

 

[phattyduck]

Does it engage the AC clutch as soon as the RPMs rise, even just a little? If so, your idle might just be a bit too low. The Toyota AC amplifiers require the engine to be at/above a normal idle before engaging the AC clutch.

I have this issue on my swapped 3s-gte Camry - the 3s-gte idles ~50rpm lower than the AC amp requires to turn on. Tap the gas, AC turns on (and idles-up) correctly. No way to fix it in that car (mis-matched AC amp and engine)...

Maybe your IAC needs cleaning and it'll just start working?

-Charlie

 

[96RedRunner]

That’s what I’m thinking.
I’m going to run a ground to the engine to frame cable

I've never been particularly careful when mounting a/c comp, was mounting surface relatively clean
bolt holes an threads rust free. Not a lot to go wrong.
A/C problems site glass tells you stuff, you having open empty system after parts I wonder how system got to being charged. Air improper charge has caused it's share of headscratchers.

[MENTION=139000]phattyduck[/MENTION] jarred my memory about IAC you swapped it with new or used it plays a part.