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Discussion Starter #1
All:

All of a sudden, my ac function quit, Yesterday afternoon after gassing
up and topping up our 164's oil from our weekend 1200 miles to Eureka
Springs for the Fall Fling of the KC chapter, AROC USA. Great fun, thanks gang!

Closer inspection, showed, that the instruments were all not
indicating, dash lights are working as are ac panel switch lights; but no temp
functions; fog light switches and all switches ac / fan seem to be
no--op. Radio has no power. Have not checked trunk lid switch or gas cap
filler door. Dash indicator light function test does not function.

Check of fuses does not seem to indicate any blown; will find my test
meter tomorrow (later this morning to verify).

Any Ideas, anyone?

Best Wishes,
Bernie Bennett
 

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Discussion Starter #2
No power to 164L instruments & ac panel & radio Help needed. Update

All Update:

Good news/bad news. Auxillary fuse panel fuse fuse 2 Control units Keyed power supply-air mixing motor (7.5 A) 10 amp actual had blown. Replacement returned power to all instruments &c. Air Conditioning returned to service for a short while when Air Conditioning fuse blew. Car can be operated on Economy mode.

Good news its November, defogging will work, gas mileage on the highway will be increased from 24.9 to 27. We have time to figure out why after less than 2000 miles on new compressor field coil, car is blowing ac fuses again.

Again, any thoughts would be appreciated.

Best Wishes,

Bernie Bennett
Brenham, TX
 

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Thanks for the diagnosis - sounds like a horrible all-lights-out event! Any ideas why it happened? Maybe the 7.5A fuse should have been a 10A fuse?

The wire to the compressor clutch always looks highly vulnerable to me - would a short there affect the second fuse you mentioned?

Cheers,
-Alex
 

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Discussion Starter #4
Alex Et Al:

This fuse: "Auxillary fuse panel fuse fuse 2 Control units Keyed power supply-air mixing motor (7.5 A) 10 amp actual" had not blown before. After the ac had been re-done this summer, compressor had begun to be noisy, preliminary to field coil failing. Blew a number of ac fuses.

We switched out compressor . . . and second one's field coil lasted about a week, less than 500 miles. Blew a number more ac fuses; but never the auxilliary fuse panel fuse 2. My guess, is over the years the fuse became a weak point. After relpacing it, ac fuse is now blowing again.

Original Diagnosis was rebuilder hadn't supplied new/good field coil and my mechanics rebuilt clutch/field coil on the car and we drove it a couple of weeks a couple of hundred miles, then took it on the road last weekend, the mentioned 1200 miles. When we got back the auxilliary fuse blew now it was relpaced, we are again blowing ac fuses.

Hope this is clear.

Best Wishes,
Bernie
 

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I have this car in my shop right now, & I have to confess to being a bit stumped. Those of us who do this for a living like to think we can solve any problem on our own, but the truth is that everyone needs a little help from time-to-time. So, here I am. Steve, I have a feeling that this one's gonna need your input.

It was actually a brand new field coil that was on the car when the aux #2 fuse blew & then subsequently the A/C fuse, & I do believe that it is the field coil as unplugging it allows the climate control to function normally in all modes. However, I plan to verify this next week by wiring in a temporary test circuit with an inline fuse to the field coil.

When the field coil that was originally on the reman'ed compressor went bad, I wasn't too surprised. A conversation with my A/C vendor revealed that he had not verified that the unit had a new field coil as I had requested. He then supplied me with a new field coil at his expense. Of course, it was installed at my expense.:mad: Once the original field coil was removed, there was no doubt that it was bad. It was quite the crispy critter. Now that I have 2 bad field coils (one brand new) in a matter of months, I am beginning to wonder if it is possible that something is killing them....& yes, I have verified that the circuit to the field coil is OK.....& yes, I made sure that when I installed the new field coil, the wire did not rub against the pulley.

Does anyone have any experience with an electrical problem causing field coil failures? The only interaction I see between the climate control circuit & aux fuse #2 is the climate control unit itself. However, I am reluctant to jump to the conclusion that the climate control unit needs replacement. I am also reluctant to blindly install yet another field coil in the car only to possibly have it fail in a couple of months. Bernie has quite a long drive to bring his car to my shop; so I do not want him to have to bring his car back for this problem again....plus, I'm sick of looking at the thing;)....just joking Bernie.
 

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Does anyone have any experience with an electrical problem causing field coil failures?
No I don't. But I suggest you check the voltage is within limits at the coil. What else could it be that causes too much energy to be dissipated in the coil windings? It's not something like the starter motor earthing back through the coil, is it? (i.e. check transmission ground cable).

Maybe the pulley has become secretly magnetised and this turns the coil into a generator...! The flux lines would not cross the coil windings though, so this is not possible (sadly).

The only interaction I see between the climate control circuit & aux fuse #2 is the climate control unit itself.
What about the relay for the compressor coil? If that was providing an intermittent connection, would the e.m.f. of the coil breaking down possibly explain the overheating of the coil windings? In other words, each time the relay loses contact, the magnetic field collapses and causes a voltage spike in the coil, except that the relay then regains contact and strengthens the spike. It's clutching at straws but it's the best I can come up with.


-Alex
 

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G'Day Alex,

What about the relay for the compressor coil? If that was providing an intermittent connection, would the e.m.f. of the coil breaking down possibly explain the overheating of the coil windings? In other words, each time the relay loses contact, the magnetic field collapses and causes a voltage spike in the coil, except that the relay then regains contact and strengthens the spike.
A very thin straw :D forget it.

Although a high voltage is generated it's low current therefore low power. Another way to look at it is the relative size of the coils, anything generated by the smaller relay coil would easily be dissipated by the larger coil. The smaller coil would melt first.
 

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G'Day Alex,
A very thin straw :D forget it.
I agree! :)

However the following part has me puzzled:

Another way to look at it is the relative size of the coils, anything generated by the smaller relay coil would easily be dissipated by the larger coil. The smaller coil would melt first.
I don't think that's what I meant?
The small relay coil is not an issue because it's not in the circuit. It is when the relay contacts open that the magnetic field in the large coil breaks down. This would (theoretically) cause a spark across the contacts. What about if the contacts were to break and re-make numerous times - would the (compressor clutch) coil get hot from switching on and off?

Hopefully you can come up with a better cause for the coil overheating ;)
By the way I like your site very much, with the transmission info and the photos of how to fix those annoying handles.

Cheers!
-Alex
 

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I have this car in my shop right now, & I have to confess to being a bit stumped. Those of us who do this for a living like to think we can solve any problem on our own, but the truth is that everyone needs a little help from time-to-time. So, here I am. Steve, I have a feeling that this one's gonna need your input.

It was actually a brand new field coil that was on the car when the aux #2 fuse blew & then subsequently the A/C fuse, & I do believe that it is the field coil as unplugging it allows the climate control to function normally in all modes. However, I plan to verify this next week by wiring in a temporary test circuit with an inline fuse to the field coil.

When the field coil that was originally on the reman'ed compressor went bad, I wasn't too surprised. A conversation with my A/C vendor revealed that he had not verified that the unit had a new field coil as I had requested. He then supplied me with a new field coil at his expense. Of course, it was installed at my expense.:mad: Once the original field coil was removed, there was no doubt that it was bad. It was quite the crispy critter. Now that I have 2 bad field coils (one brand new) in a matter of months, I am beginning to wonder if it is possible that something is killing them....& yes, I have verified that the circuit to the field coil is OK.....& yes, I made sure that when I installed the new field coil, the wire did not rub against the pulley.

Does anyone have any experience with an electrical problem causing field coil failures? The only interaction I see between the climate control circuit & aux fuse #2 is the climate control unit itself. However, I am reluctant to jump to the conclusion that the climate control unit needs replacement. I am also reluctant to blindly install yet another field coil in the car only to possibly have it fail in a couple of months. Bernie has quite a long drive to bring his car to my shop; so I do not want him to have to bring his car back for this problem again....plus, I'm sick of looking at the thing;)....just joking Bernie.

Bernie I wonder what Skip would say? Oh, I know those d**n V6 Alfas
Mike FYI if it ain't 4-cylinder Skip don't want to mess with it.

Sounds like a bad ground or improper air gap between clutch plate and clutch pulley. Couple things come to mind:

Does compressor have good ground wire bolted to lug of compressor and is wire grounded good back to chassis?

Do clutch coils have two wire system with one a ground wire back to compressor case or is/are they one power wire coil types as OEM was, if so does snap ring lock coil back plate tight to compressor case.

Good bearing in clutch pulley? Proper oil in compressor (ester not PAG) if R134conversion?

Binding compressor will cause clutch to overheat, too.
 

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Discussion Starter #10
A/C Fuse Blowing 164 L wasNo power to 164L instruments & ac panel & radio Help needed

All:

History. Car was in for service and my complaint was slipping belt on AC as I would occasionally get a squeal and it would go away if I cut AC off or backed off accelerator.

Mike did lots of things to bring car up to date and as we got ready to take it home we discussed the noise which was not slipping belt. Planning to take the car to Detroit, I did not want Ac to fail and so asked for rebuilt compressor to prevent spousal ac failure unhappiness.

Replaced ac compressors worked during week before trip was about to start; but squealing sound was back and cycling the system to off or Economy mode made annoying squeal go away. Until system began blowing ac fuses when Auto was pressed.

We took the Spider to Detroit and when we got back, Mike put a replacement compressor in which worked for about a month and a couple of thousand miles. Including a trip to Eureka Springs for the Fall Fling. When we got back some time passed and the fuse issue which engendered my first message and to which Mike Kieth replied recently occurred.

Just wanted to get the full history on paper (???) well you print this out if you want it on paper, on record to see if this sparks anyone's thought processes.

Best Wishes to All
Bernie Bennett
 

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All:

History. Car was in for service and my complaint was slipping belt on AC as I would occasionally get a squeal and it would go away if I cut AC off or backed off accelerator.

Mike did lots of things to bring car up to date and as we got ready to take it home we discussed the noise which was not slipping belt. Planning to take the car to Detroit, I did not want Ac to fail and so asked for rebuilt compressor to prevent spousal ac failure unhappiness.

Replaced ac compressors worked during week before trip was about to start; but squealing sound was back and cycling the system to off or Economy mode made annoying squeal go away. Until system began blowing ac fuses when Auto was pressed.

We took the Spider to Detroit and when we got back, Mike put a replacement compressor in which worked for about a month and a couple of thousand miles. Including a trip to Eureka Springs for the Fall Fling. When we got back some time passed and the fuse issue which engendered my first message and to which Mike Kieth replied recently occurred.

Just wanted to get the full history on paper (???) well you print this out if you want it on paper, on record to see if this sparks anyone's thought processes.

Best Wishes to All
Bernie Bennett
What is VIN of this 164 is it early production in 1990?

I am looking at aux fuse box G2 7.5A fuse F2 you say is blowing in additions to a/c 10A fuse F12 in main fuse box G1. I think we pretty much agree a/c clutch coil problem blowing F12 but back to G2 in aux fuse box.

Among other things F2 aux fuse powers it also powers stepper motors Q30A/B and internal temp sensor fan motor Q33 on earlier models. Does this car have that little slot car type looking motor attached to stepper motor bracket inside small tire pressure decal panel inside glove box? Is that motor seized or wire shorting to something like steeper motor steel bracket?
 

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It's a single wire coil, & the ground wire is good. As for the air gap, I'm not sure. Because the lip of the pulley extends past the clutch, I didn't see a way to measure air gap, but the pulley spun without dragging on the clutch, & the clutch engaged firmly with no slippage.

It is a 134a car, & when the compressor was replaced, the whole system was flushed out & replenished with Ester.

It is an early production model. I'll check that temp sensor fan motor.

Thanks,
 

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Discussion Starter #13
No power to 164L instruments & ac panel & radio Help needed

Steve:

SN: ZAREA43L7M6196284.

Thanks for your input.

Best Wishes,
Bernie Bennett
 

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Steve:
G2 fuse only blew once. When it was restored A/C fuse began to blow,immediately.
Bernie
OK then that was probably just a one-time fluke!

As for compressor clutch coil overheating and/or now just blowing F12 10A
fuse there must been a short to ground somewhere.
 

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There's no doubt that the coil is fried. When I disconnect it, the climate control operates normally in all modes, & the coil only has 3.5 ohms of resistance to ground.

With 2 coils fried in roughly 4 months of use, the 2nd being brand new, I can't help but conclude that this is something more that the 164's normal propensity for this type of failure. I'm afraid that if I just throw another coil on it that it too will fail in short order. However, I'm at a loss to figure out what could be causing this sort of failure. OTOH, the car had not had any problems with coil failures for a very long time before we replaced the compressor. We originally replaced the compressor because its clutch was slipping.
 

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There's no doubt that the coil is fried. When I disconnect it, the climate control operates normally in all modes, & the coil only has 3.5 ohms of resistance to ground.

With 2 coils fried in roughly 4 months of use, the 2nd being brand new, I can't help but conclude that this is something more that the 164's normal propensity for this type of failure. I'm afraid that if I just throw another coil on it that it too will fail in short order. However, I'm at a loss to figure out what could be causing this sort of failure. OTOH, the car had not had any problems with coil failures for a very long time before we replaced the compressor. We originally replaced the compressor because its clutch was slipping.
I would be inclined to be suspect of compressor binding internally then.
 
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