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1992 Toyota Camry a/c lite flashing

GM Tech on Fri May 28, 2010 11:13 PM User is offline

Refrigerant Type: R-12

So, yeah, I'm crossing over-- this Camry had a condenser leak- replaced condenser - and compressor will not come on- unhook battery- no good--then I notice a/c lite flashing- My Mitchell-On-Demand says it's either the RPM sensor or the a/c amplifier-- RPM sensor resistance is 105 ohms-- good according to spec of 100-130 Ohms-- The a/c amp test is to test the feeds to it-- all those are good- so it looks like I need an a/c amp-- But I would like some feedback- who has seen this before? What are my chance the a/c amp is at fault? Where do I get an a/c amp- dealer item only? boneyard?

How do I know the rpm sensor is sensing? the only test is a resistance test- and it passes-- how about a position test?

Basically what is the most common fix when the a/c lite is flashing?

Thanks- I need to know a Toyota a/c expert.......

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Dougflas on Sat May 29, 2010 5:56 AM User is offline

The rpm sensor may be a hall effects type sensor. Can you supply 12 volts to engage it manually and then monitor the output with a scope? Will try to look the circuit up for you.

Chick on Sat May 29, 2010 7:45 AM User is offlineView users profile

Seldom is it the RPM sensor, usually the Amplifier, bone yard is your best bet for those... We sell every one, it's a little square box under the passenger side of the dash...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Edited: Sat May 29, 2010 at 7:51 AM by Chick

mk378 on Sat May 29, 2010 9:43 AM User is offline

There's the outside chance the amplifier is OK and there's another problem. Does the compressor even try to engage? When working properly, the amplifier system will engage the clutch then start checking the rpms. If the amplifier detects the compressor is not turning when it is supposed to be, it will kill the clutch and start the light flashing. So besides a problem with the amplifier or sensor, it could also be a blown fuse, bad relay, or bad clutch. You could jump the the clutch to the battery (engine OFF) to see that it works.

Also a lot of those Japanese modules don't really blow up, all that goes wrong is a solder joint on the circuit board cracks and they stop working. You could try prying the amplifier open and resolder everything inside.

Edited: Sat May 29, 2010 at 9:49 AM by mk378

GM Tech on Sat May 29, 2010 10:05 AM User is offline

This is where working by yourself sucks---When I press the a/c button, the lite comes on for about 10 seconds-- engine revs up, pressures never change, then lite starts flashing-- so maybe RPM sensor is doing its job- flashes the lite when it senses no clutch turning--so why does Mitchel-On- Demand say it is either rpm sensors or a/c amp-- I have jumpered what I think is a/c relay- it is the only relay in the box underhood, labeled as a/c mag-- compressor does not engage-

I need the aid of a helper to turn on switch, while I tap on clutch-

Can someone tell me what happens when the RPM sensor senses no rpm? Does the light start flashing? like I'm assuming. Heck, I've got the glove box all emptied, and all those mystery panels off- got the a/c amplifier hanging down-- and perhaps all I have is the system doing its job-- the diagnosis in Mitchel assumes a bad part- never once mentions it might be working properly- and flashing the lite because the compressor does not engage.-- I'll jumper out the relay, see what is going on at the pump....

I have the wiring diagram-- just can't find the proper components- like j/b #1, j/b #2 etc wiring diagram calls it an a/c relay- yet underhood it is called a/c mag---is this the same component?

Thanks for your input....

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

GM Tech on Sat May 29, 2010 10:40 AM User is offline

Update-

I found out the a/c mag relay engages ( shows 12v across relay coil) for 5 seconds or so each a/c request cycle- then shuts down and dash lite flashes- this confirms my assumption that the rpm sensor must be doing its job- when a/c amp checks for pump rpm, and sees none, it flashes the light-- sure wish Mitchel would have mentioned that!

Anyway, I have fed the clutch circuit 12v, engine off- it is pulling just under 3 amps, so looks like a good coil- next I will pull off panels and force the armature against the pulley face- just reaching in, one side at a time, the armature won't cling to the pulley face- so I'll try pushing the entire armature even against the pulley face- this thing hasn't run since last year, so there is most likely lots of corrosion in there. looks like a pump removal to adjust air gap though... pretty tight in there.

This is strange- I fed it 16 volts from an external power supply- compressor turns easily by hand- slips when engaged- turns about 60 rpm-- I figure the rust behind it needs to come off- let it slip for a couple minutes- clutch is still touchable-not getting hot like you'd think..- its as if there is not enough magnetic pull to hold armature in tight-- I can feel the pull with my screwdriver just fine-- looks like the pump need to come off and start swapping parts- like coil etc-- I Have a used Denso on my bench....



-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Edited: Sat May 29, 2010 at 11:05 AM by GM Tech

Dougflas on Sat May 29, 2010 5:58 PM User is offline

Do you have the MACS cd rom service literature? If you do, that is the info that I have. They list a lever system and a push button system. Which do you have?

GM Tech on Sat May 29, 2010 10:28 PM User is offline

I got it fixed!

The air gap was too wide- removed both shims and it works great-- was able to dismount compressor and angle it down to where I could get to clutch-- that overhung pulley won't allow you to use a shim gage- so I pulled them both out- pulley does not rub--

Sure wish I had known the a/c lite flashing meant the clutch wasn't turning -- I thought it was a trouble code all along--

Put the glove box back in- cools good now.. mark this one up to a PITA learning experience-- putting that compressor back on was not fun.

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Cussboy on Sun May 30, 2010 12:08 PM User is offline

Quote
Originally posted by: GM Tech
putting that compressor back on was not fun.

Somewhat off-topic: But as dumb as it might sound, one thing that directed me to both my '94 Suburban and my '88 Mazda B2200 was that the AC compressors were very accessible, right on top, instead of on the bottom. And since I'm in Arizona, I figured that these would need replacing (several times), 200K on suburban and 170K on the B2200.

Now my 1998 Nissan Frontier has the compressor somewhat obstructed, but not only is that one original at 160K miles without ANY AC work ever, it is the smallest compresser I've seen, and that vehicle has the best AC of any of my vehicles.

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