Automotive Air Conditioning Information Forum (Archives)

m32825 on Fri September 30, 2011 7:44 PM

Year: 1987
Make: Toyota
Model: Camry
Engine Size: 2L
Refrigerant Type: R134a
Ambient Temp: 85
Pressure Low: 30psi
Pressure High: 200psi
Country of Origin: United States

The A/C in my '87 Camry has begun to occasionally decide not to work. The blower still runs, but I get a blinking light indicating an issue and no cooling. Turning it off and back on does not seem to change things. On the drive to work in the morning it never started to cool, but at lunch it worked fine. It worked fine for the first half of the drive home (all highway speeds), but then stopped. Pressures look good when it is operating. I have watched the clutch when it is in the "not running mode" and when I hit the button to turn on the A/C, it never engages at all. I have checked the wiring to the compressor and nothing seems loose or marginal. When it runs it cools fine, but I can't figure out how it decides whether to run. I'm hoping you guys can give me some suggestions to resolve this mystery, thanks in advance!

-- Carl

GM Tech on Fri September 30, 2011 8:24 PM

Flashing lite means compressor has been disabled due to rpm detector either being bad, or detecting a difference in rpm of compressor and compressor pulley---if clutch is slipping, rpm detector is doing its job-- if compressor never runs then rpm sensor in compressor is probably bad-- compresor should come on at each control head command and run for at least 2 seconds until rpm sensor shuts it down....last one I did like this, I put a salvage compressor on the car to get out of the issue. The sensor itself is replaceable as far as I know.

-------------------------
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......

m32825 on Fri September 30, 2011 10:06 PM

> ... if clutch is slipping, rpm detector is doing its job-- if compressor never runs then rpm sensor in compressor is probably
> bad-- compressor should come on at each control head command and run for at least 2 seconds until rpm sensor shuts it down.

More info... a couple months ago I replaced the compressor and clutch (front bearing leaking oil). The new one shows no sign of slippage, when it decides to run it locks up and goes like a champ.

If it were running a couple seconds and then shutting down I would suspect belt or clutch issues. What's got me baffled is that I'm seeing it run fine sometimes but then not engage the clutch at all on other occasions.

Is there a way I can temporarily bypass the rpm sensor to see if that makes the problem go away?

-- Carl

mk378 on Sat October 01, 2011 8:11 AM

Check the clutch gap. Gap too wide will cause it to fail to engage, especially when hot. It is common for "new" rebuilt compressors to be set up with the wrong gap. It could also be the compressor relay. In either case, since the compressor didn't start when it should, the sensor then (correctly) sees that the compressor is not turning, and the system goes to lockout with the blinking light.

If the rpm sensor were bad it would engage for a few seconds, then stop.

m32825 on Mon November 07, 2011 6:54 AM

Update: it has been over a month since this last occurred, been running fine since. I'm guessing there was a marginal electrical connection and reseating all the connectors improved it. Thanks for the suggestions, if it starts happening again I've got some good ideas to follow up on.

-- Carl