OMP

Patient is a 200 10V Automatic ( 1989).
Long IP with voltmeter.

When first starting the car : All gauges work right away ( at ignition) except the Voltmeter. Even after starting the car, voltmeter will read 0 ( no movement at all), and THEN, about 2-3 seconds after that, Itīll jump to about 14.

From my perspective, I donīt really think is a problem ( in my mind, or maybe I am wrong).

Problem comes when running for a while.....The more time goes by, readings at the voltmeter will then go down......After driven fro a while, 20 minutes or so, at idle ( 800 rpms approx) with no electrical charges ( no lights, no A/C, no radio, no nothing), Itīll read above 12 ( Iīd say 12,5 or so). SO no issues.

However, When engaging electrical elements ( A/C, lights basically), voltmeter will read clearly below 12 ( Around 11 ). This would be at idle also. Driving the car, Itīll read above 12 but not by much.

However, when stuck in traffic, and fan kicks in, with lights and A/C, voltmeter will read clearly about 10.

The most critical part of this is that A/C will be cutt off because of the voltage drop. Once into higway speeds ( and thus, voltmeter above 12), A/C will work perfect.

So, having had this issue for a while, last year a put in a brand new alternator ( Bosch) so I thought that could be the issue, but results were exactly the same.

So this year, the mechanic having some time, he checked all POSITIVE spots coming from the battery trhough out the car ( ALternator, battery, and so on), and even with all electrical elements ON, there is no reading below 12,2 approx.

So, for the moment, we are seeing the the Voltmeter is not reading the correct voltage....WHICH I woudnīt mind, but then, I canīt seem to understand why the A/C is cutting off when reading in the Voltmeter goes below 12V.

I have read about the Voltage Stabilizer ( not the regulator in the Alt) but all instrument cluster is working fine so I donīt know what could be the culprit on the A/C cutting OFF.

Is the A/C compressor taking voltage signal anywhere from the IP???? From the logical point of view, I donīt really see this a very logic thing ( actually I see it as a stupid thing).......But I cannot think of anything far from there...

Any ideas?
Thanks

bradwilcox

Is your alternator the 115 amp variety? I think 90 amp is sometimes found and it's not really good enough?

Do you know about using the climate control to spy on various sensor readings? With car running:

Tip 12

Test with compressor running vs. econ mode, etc.

OMP

Thanks Brad.
I donīt know about the amps on the alternator. Iīll check that.

The voltage on the A/C head also, havenīt have the chance to do it yet.

However, strange thing is that the mechnic called me yesterday and he is measuring about 11,5 Volts at the Main Relay panel under the steering wheel.

All important electrical consumers seem to be OK: Voltage at Alterntor is 12,60, at Battery is about 12,40 and about 12,40 at the starter motor.

I have told him about the splice or "Y" under the passenger side carpet and he didnīt find any other cable that the main one coming thru the Firewaal and going back to the battery.


So, at this stage, the strange thing here is the 11,50 Volts coming at the Relay panel. Where can this difference be? How is the Relay panel fed? From where?
Also, I am asuming that because it is below 12V, the A/C head will get slighlty less and thus, the signal sent to the compressor is clearly below 12, turning off the compressor because of the lack of those 12V.

Is this the deal? Is the compressor voltage signal coming from the A/C Head? Does it works that way?

If it is that way, I can think that the culprit is somewhere between the (Battery??) and the Relay panel?

Bently doesnīt really show where the voltage is coming into the Relay panel, or at least I havenīt seen it in the "Electrical System" Volume

Any feedback would be appreciated.

Thanks

bradwilcox

http://www.sjmautotechnik.com/troubl...ting/elec.html