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post #1 of 15 (permalink) Old 06-14-2007, 07:33 AM Thread Starter
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A/C question

I've got my A/C going but my compressor is cycling. I've doubled checked freon level (using Freeze-12) and am ok on that end.

My compressor kicks on for about 10 seconds then cycles off for about 15 seconds then repeates. When running, I can cycle the compressor off and on with the temperature ring, so that appears to be working correctly.

From looking at Papajam's scematics, I can tell that the signal for the compressor to cycle is from the controller under the dash. I can see my controller and am planning on pulling the connector off the check the thermistor.

Does anyone know of a source and estimated price for an A/C thermistor for an '84 Spider? I've searched the threads and found alot of good information but nothing on how to R/R the thermistor. Any instructions on how to get to the thermistor to replace it?

Thanks,
Don
Thanks.

[FONT="Microsoft Sans Serif"]Don - 1984 Spider Veloce[/FONT]
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post #2 of 15 (permalink) Old 06-14-2007, 09:37 AM
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What are your high and low side pressures?
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post #3 of 15 (permalink) Old 06-14-2007, 01:09 PM Thread Starter
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Don't have the exact numbers as I had the recharge done while my car was in for other unrelated work. When I got the car back and drove home, I noticed the compressor cycling. I took the car back to the shop and watched as they checked things again. The mechanic put his gauges on the car but I can't recall the exact pressure.

I'm guessing 150 or so on the high side and about 40 on the low.

No air bubbles in the site glass (I looked before I took it back), confirmed by the mechanic.

[FONT="Microsoft Sans Serif"]Don - 1984 Spider Veloce[/FONT]
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post #4 of 15 (permalink) Old 06-14-2007, 03:10 PM
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This may sound like a stupid question-are the vents(small ac vents) on the sides of the center console moulded, as one single side console or screwed on. This will let me know if the ac is a factory installed or dealer/port installed
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post #5 of 15 (permalink) Old 06-14-2007, 10:10 PM Thread Starter
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molded side vents.

Did a couple of things to the A/C tonight.

1. A/C fuse and holder in the engine compartment were hosed. Replaced both and verifed the condenser fan works (as does the aux fan relay).
2. Jumpered across the thermistor and noted no change (compressor still cycled). I removed the jumper after the test.

3. Jumpered from Pin 3 to Pin 2 (A/C blower output to controller output) No change noted. Removed jumper after test.

4. Jumpered +12 vdc from a (switched) fuse to the #2 pin of the connector on the AC control module under the passenger side of the interior. Compressor and condenser fan run when ignition is turned on. Compressor runs without cycling. Verified on 5 mile test drive. Left the jumper in place so I can use the A/C until problem is solved.

I don't know if jumpering (shorting)the thermistor lead was a valid test as I don't know what the resistance range of the thermistor is. Maybe my AC controller is bad.

Does the controller need to be grounded with the mounting screw? My controller was just hanging under the dash with the screw loose.

Progress....at least I'll have AC!

[FONT="Microsoft Sans Serif"]Don - 1984 Spider Veloce[/FONT]
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post #6 of 15 (permalink) Old 06-15-2007, 04:09 AM
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Not having a wiring diagram in front of me- I'm going to guess that you didn't check the ac fuse in back of the fusebox. There is an inline fuse holder on the wiring side(back) of the fusebox. It is best to pull the fbox down not only to see the fholder but also to check the connection. 82 thru 84 spiders might have this connection butt connected with a plastic 2 to 1 wire scotchlock. There might not be enough amps running through these connections to operate the ac system. If the wire has a in line fuse that uses a ceramic or glass fuse it should be replaced with a blade or GM style fholder. If the wire is connected using a plastic butt connecter it should be soldered.
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post #7 of 15 (permalink) Old 06-15-2007, 05:28 AM
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Quote:
Originally Posted by dghii View Post
molded side vents.

Did a couple of things to the A/C tonight.

1. A/C fuse and holder in the engine compartment were hosed. Replaced both and verifed the condenser fan works (as does the aux fan relay).
Where did you find the engine compartment fuse and holder? I'm been looking for mine on my 91 Spider maybe their in the same place?

Darkside Member

Last edited by msiert; 06-15-2007 at 05:31 AM.
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post #8 of 15 (permalink) Old 06-15-2007, 05:41 AM
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91 spiders are different all fuses and relays are in the fusebox
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post #9 of 15 (permalink) Old 06-15-2007, 07:38 AM Thread Starter
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I've never heard of a fuse behind the fuse box for the A/C. It doesn't show up in any wiring diagram or is it mentioned in my owners manual. What would the fuse be for?

My AC worked great this morning, with my bypassing the controller. I'm going to try to pull the controller this weekend and see what is up with it.

[FONT="Microsoft Sans Serif"]Don - 1984 Spider Veloce[/FONT]
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post #10 of 15 (permalink) Old 06-15-2007, 10:42 AM
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The fuse powers the controler,ac relay and the switch. The outside fuse in the engine compartment is for the auxfan. i have only replaced one controller ever, but that does not mean it isnt the problem. Behr a/c is or was located in Houston and my have the part. I also have never found any decent wiring diagram for the alfa's but the system is so primitive thats its pretty easy to repair. The controller is generic and can easily be matched up to other applications. 3 main problems come to mind in your senerio: 1 The fuseholder which burns or the wire connection is butt conected and burns 2 A/C relay or relay ground(with is screwed into the top of the relay on the right inner fender) 3 Too much gap in between the ac clutch applying plate and the pulley
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post #11 of 15 (permalink) Old 06-15-2007, 11:32 AM Thread Starter
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Thanks for the responses.
First off, I thin my AC clutch plate and pully are ok as I am running the AC without problems and it is cooling the car.

Were does the power come into the controller (which pin)? My diagram shows the following pinout for the controller.

1. Ground
2. output to AC aux fan relay (coil #86) and compressor clutch
3. Input from AC fan switch
4. ground
5. from AC temperature control ring
6. from AC temperature control ring
7. Thermistor
8. Thermistor

Thermistor may still be the culprit as I have not check its resistance. When I jumpered across 7 and 8 the compressor cycled

Tried applying 12vdc to pin 3 and compressor still cycled

When compressor was runing, I could cut it off and on by adjusting the temperature controller.
When compressor was cycled off, temperature controller had no affect.

All three blower speeds work correctly.

I currently have 12vdc applied to pin 2 as a stop gap and the system is working. Granted, I know I haven't solved the 'problem' but at least I have AC working until I do!

[FONT="Microsoft Sans Serif"]Don - 1984 Spider Veloce[/FONT]
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post #12 of 15 (permalink) Old 06-15-2007, 12:10 PM
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I am sorry to say but I believe this information to be wrong. The wiring on this switch is for an 86 thru 88 1/2. That is when they started to hook up the aux fan to the ignition so the aux fan would not run after thr car is turned off- big problem with dead batteries 82-85. I'm still drifting towards the fuselink behind the fusebox. In additon to the fuse mentioned, the fuel pump used the same fuse holder and melted. Best of luck Eric
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post #13 of 15 (permalink) Old 06-15-2007, 01:21 PM Thread Starter
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I'll look for the fuse behind the box. The schematic I'm using is the one papajam developed for the '84.

[FONT="Microsoft Sans Serif"]Don - 1984 Spider Veloce[/FONT]
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post #14 of 15 (permalink) Old 06-15-2007, 03:54 PM
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Take a look at this thread. It discusses the a/c fuse that lurks behind the fuse panel in Series 4 Spiders. There's even a photo of one. http://www.alfabb.com/bb/forums/showthread.php?t=41372
David

David
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post #15 of 15 (permalink) Old 06-16-2007, 09:06 AM Thread Starter
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Thanks for the link. I looked for the fuse in my 84 yesterday but didn't see it. I'll look again to today.
I don't think that it matters in my case as my ac fan works fine and blows all three speeds.
I' tried jumpering 12vdc to the #3 pin on the AC control module with no change in the cycling. The #3 pin is the output from the AC fan switch to the contol module.

[FONT="Microsoft Sans Serif"]Don - 1984 Spider Veloce[/FONT]
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