After consulting my 2000 EWD, it looks like the ac amplifier is looking for engine rpm from the ecm in order to engage the ac clutch. My guess is your problem has to do with that part of the equation. Either the ecm isn't sending a good engine rpm signal to the ac amplifier or the ac amplifier isn't telling the ecm to increase the idle so the ac compressor can engage.
AC has me baffled…
- Thread starter T4Rscott
- Start date
phattyduck
Elite Member
What's the engine RPM at idle? (not what's on the cluster, get another instrument to check - OBD-II reading, etc.)
The AC amp won't activate the clutch unless RPMs are sufficient. (this is an issue in one of my other toyotas... I have to tap the gas to get it to engage, then idle-up keeps it engaged)
-Charlie
The AC amp won't activate the clutch unless RPMs are sufficient. (this is an issue in one of my other toyotas... I have to tap the gas to get it to engage, then idle-up keeps it engaged)
-Charlie
brillo_76
Elite Member
So your thinking is the idle up isn't working. Very good thought.
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phattyduck
Elite Member
Sort of - the 5VZ doesn't idle up much with AC. I'm thinking that the AC system thinks the engine is too low in RPM to turn on, not so much whether the idle-up works. (idle up is controlled with the idle air controller these days, not a separate VSV like in the 80's and early 90's Toyotas).So your thinking is the idle up isn't working. Very good thought.
-Charlie
T4Rscott
New member
So, when the engine is first started, it will rev to about 1300 and if I push the AC switch it will rev to about 1400.
I hope the amplifier isn’t the issue, I replaced it not long ago, and it is an OEM part
What about when the engine is at operating temperature?
T4Rscott
New member
When at operating temp, it does not jump up in rpm
brillo_76
Elite Member
Did you try what this member suggested? As if the voltage is there at idle?
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T4Rscott
New member
I have not had time yet.
This would also prove if your circuity is working properly too.That’s why your ac clutch isn’t engaging at idle. The ac amplifier isn’t seeing a high enough engine rpm to allow for compressor clutch engagement. I wonder if there is a way to bypass that.
brillo_76
Elite Member
For testing, can't he just apply 12volt to the magnetic clutch compressor and monitor the ac clutch feed wire with a mult meter to see if it's kick on and off propetly?
See if it the clutch compressor working properly.
I just tape the wire jumpers in place and monitor all from in cab powering the ac clutch off our cigarette lighter adapter plug.
If the meter is going 12volt then when it clicks goes out when the ac relay kicks on and off. The ac amplifier is working properly.
If it's not sending voltage yo the mag clutch the issue would be in the sc circuitry.
If nothing else these jumpers would eliminate components as good or bad if nothing else?
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Since the compressor clutch engages at higher rpms then that part of the circuit is intact and not the issue. The problem is the ac amplifier not telling the compressor clutch to engage at idle which would be due to low engine rpm. Since it engages at higher engine rpm's I would think that the signal from the ecm is fine. I think the most likely culprit is the ac amplifier not telling the ecm to idle up for the clutch to engage. Either the ac amplifier is at fault (not likely since it was replaced with OEM) or the circuit between the ecm and ac amplifier for that signal/request is the problem.
brillo_76
Elite Member
Man I hope it's not his ac amplifier again.. My ac issues are mostly rotted out Condensers. Warn out compressors.
I was theorizing that the gap in the clutch is just big enough. That at low rpm it engages and slips and at higher rpm it latches and doesn't slip. However, your not getting the correct rpm signal or the ampflier not sending the engage signal at low rpm.
Maybe the densos magnetic clutches are all or nothing as I can't say I even had a magnetic ac clutch fail on a Toyota.
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I was theorizing that the gap in the clutch is just big enough. That at low rpm it engages and slips and at higher rpm it latches and doesn't slip. However, your not getting the correct rpm signal or the ampflier not sending the engage signal at low rpm.
Maybe the densos magnetic clutches are all or nothing as I can't say I even had a magnetic ac clutch fail on a Toyota.
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BlackWorksInc
New member
So let's start from the beginning I guess?
What is the confirmed engine idle after warm up?
What is the confirmed engine idle after warm up?
T4Rscott
New member
It’s within spec 7-750
T4Rscott
New member
[MENTION=8262]badluck[/MENTION] is on the correct path. It's in ac circuitry. His theory are extremely solid. He explains it on my question post on how to test it with wire jumpers from your cab.
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I just have to know where to look, and what to test.
I have a 2000 EWD which would be close, but you really need to find a 99 EWD to reference for circuit testing.
