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Old 09-09-2007, 01:24 PM   #1
pepe10
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Default AC Compressor and Blower are Not Working

Help! I will try to explain how I got to where I am. During restoration of my 1982 CE, I chose to put in a 180 thermostat because I read that the cooler the engine, the more HP. My Corvette guy did as I asked. I also replaced the original AC Control panel with one from Ecklers (made in China - not surprisingly). I have had nothing but trouble and have replaced the AC Control panel twice since with the same. I was still having vacuum problems and the vents were not opening properly.

Now let me jump back. I was also having an Aux fan problem...like it would not come on line. So a friend rewired the Aux fan to a manual switch. After rebuilding Aux fan... it worked fine. Why the manual switch?..probably engine running too cool to kick it on.

Voila...the car was also not going into torque converter lockup because the car was running too cold. (Needs 195 to do that). So I change the thermostat and the Torque Converter lockup works great as it should.

Now I am thinking about the Aux fan...maybe it needs a hotter engine to run as well. Recently while only able to run the AC in Max - fan would operate at all speeds - I began to have intermittent problems with the fan while in AC. (Can't have that in Tampa, Florida in the summer). I found that the reason for the fan problem was that the ground my buddy built while rewiring the Aux fan was shorting and there was a steady glow from the poor ground.

I said enough is enough and yanked the aux fan manual wiring and tested the Aux fan which is running great now as it should - what do you bet it was the thermostat.

I have not been able to get the fan to work or the AC Compressor to come line since (it has been nearly two weeks). I have tested and tracked the electricity from the Fuse panel to the fan switch and out the the other side. I have tested the AC panel switch from the fuse panel to the switch and out agian. I believe I have tested and checked all of the grounds around the High Speed Blower relay and the resistor. Had spares of each and tried those as well. I have had to rewire some connections with respect to the relay and resistor and all are making good contact.

I went to Corvette Generation in Dade City, FL where Wally has two acres full of C-3s and 4s and picked up a old AC panel (made in the USA) and it has fixed my vacuum problems. (The "C" Clip holding the AC switch together had come apart - again on the made in china unit- and I needed the new panel anyway to solve for the vacuum issues).

Sorry for the long story but I don't know what to do next. I see in the shop manual that there is supposed to be "A second fuse, to protect the high speed blower circuit, is located in the electrical wiring between the junction terminal and the Air Conditioner realy." Does anyone know where that location might be????

I hope the long story gives you enough background on my efforts...I am struggling to come up with any other ideas but will recheck all of my grounds if I can find them.

Thank you!
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Old 09-10-2007, 10:30 AM   #2
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There really is not another fuse is there! The ground to the engine block is clean and is functioning just fine.
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Old 09-10-2007, 01:24 PM   #3
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OK, Take a deep breath. You have 2 or 3 things going on here.
1, the Aux Fan. It is designed to work ONLY if the engine gets real friggin hot, 238*. That will happen if your in slow moving traffic, hot day, AC on, no moving air. Yea, I know thats too hot, but thats what the general did. POS fan anyways. So if the car isn't overheating the fan will not come on so don't worry about it.
2. AC blower. Stick a test light in the connector to the fan and the ground post on the firewall, right there on the corner of the evap box. Turn the fan on high, the light should come on full bright. If it does not, move the ground to the engine, does it light now?
Here is a schematic for an 81, should be the same
Click the image to open in full size.

There is no "fuse" to protect the blower on High, it feeds directly off the fuse link coming off the starter and feeds other stuff too, so if everything else is working, thats not the problem.

There should be a ground strap from the ground stud on the firewall to the back of the passenger head. It is the ground point for the blower And the wiper motor, make sure it is actually grounded.

If that don't get ya fixed up, let me know, I can walk you thru troubleshooting the thing step by step
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Old 09-10-2007, 03:47 PM   #4
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Many thanks for your post. It now seems that I will be traveling out of town tonite and not return until Thursday. I will likely not get back to you until then unless I can break away for a quick test.
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Old 09-10-2007, 04:34 PM   #5
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Well, my first conference call ran late and so I missed the second. I can thank someone for being longwinded (though some might suggest that description would fit me). I did run the test...hopefully as you directed...I tried several firewall bolts/studs but believe the one to which you were directing me is located just under the Blower Relay and got no light. However, I grounded to the engine and I did get a light. Sounds like a grounding problem somewhere.
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Old 09-10-2007, 04:55 PM   #6
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Sure enough, the wiper motor is not working either.
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Old 09-10-2007, 05:11 PM   #7
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Yep, there ya go. There should have been a braided copper strap connected to that stud and the back of the head. If its not there, make a ground wire with at least a 12 ga wire and connect it to the same place, should be good to go
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Old 09-10-2007, 05:41 PM   #8
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I want to make sure I understand but are you saying a strap from the stud on the evap housing/firewall to the back of the head on the engine???
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Old 09-10-2007, 09:51 PM   #9
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Yes, thats how the ground side of the fan and wiper motor get a ground
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Old 09-13-2007, 10:19 AM   #10
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Sixfooter, please bear with me as I try to turn this thread into a learning experince. I have found that, for even an idiot like myself, one is able to stumble their way into discovery.

I became fixated on the wiring diagram on page 8A-69 of the shop manual and tried to follow the ground attached to the back of the bell housing and track it back to the HS Blower relay. I realized last night that the relay ground is what you were talking about that runs to back of the cockpit and is linked with the defogger and not to the engine as depicted in 8A-69. I also noted that the diagram on 8C-29 shows the ground linking with the wiper switch ground. Though I reviewed your diagram above, found in the AC section of the manual, it is what finally turned the light on for me.

So it appears that I need to trace this ground to the right hand side of the car to the roof pilar where the ground for the defogger is located to see if there is continuity. Does that sound correct?

Now, here is what happened at the moment that the ground went bad a couple of weeks ago. I could not get the hood open because my buddy had spliced the ground from the relay into the manual switch wiring and grounded it to the right hand hood latch near the relay. It cooked and melted the plastic on the hood release cable so that the latch would not release. I turned on the wiper to gain access to the thumb hole used to release the latch manually, nearly fried my thumb, and popped the hood open. That is the moment the ground went bad and the wiper motor no longer works as well as the AC Blower relay.

Do I need to check the instrument harness ground on the left hand kick panel as well. I am going to anyway but thought I would ask since I believe the wiper switch is grounded there as well.

Thanks for all your help.


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Old 09-13-2007, 12:02 PM   #11
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This one might make some more sense and be easier to follow. The groung for the blower relay, wiper morot, blower motor all get their ground thru the stud on the firewall and the braided strap that should be on the stud and the back of the pass head. I haven't looked into the grounding for the defog, my car has it but I have not looked, I'll do that tonight. Your Buddy Bubba gave you a nice hookup on the hood latch ground, that sux. Take a look at this one and see if it helps
Click the image to open in full size.
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Old 09-13-2007, 01:33 PM   #12
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Wish I had a shop manual in color. Mine is black and white and I have to be very careful tracing the color names. Your last chart is the same as mine on pages 8A-69, but the difference on my chart, there is a horizontal line that runs from the AC compressor solenoid linking to the ground from the relay like yours to the base of the blower motor with the same connect to the engine block like yours..

From what you are describing I still need a strap from the firewall stud to the engine (bell housing). But that does not explain what went wrong and what I am trying to nail down as the culprit.

Thanks again for your assistance.
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Old 09-13-2007, 01:45 PM   #13
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Quote:
Originally Posted by pepe10 View Post
From what you are describing I still need a strap from the firewall stud to the engine (bell housing). But that does not explain what went wrong and what I am trying to nail down as the culprit.

Thanks again for your assistance.

You will find three large hole terminals in the wiring harness to the starter. The terminal attached to a black wire does NOT go on the starter lug with the other two. This wire is the ground for the wiper and blower motors. It should be attached to a bell housing bolt.
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Old 09-13-2007, 02:01 PM   #14
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I do have a two wire terminal attached to the bell housing. Thanks. I have never touched that one except to clean and replace last week.
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Old 09-13-2007, 07:44 PM   #15
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Houston, we no longer have a problem!...well, now it is a different one. I found the faulty ground...and I am embarassed to say it was right under my nose. The fault was found in the connector just below the High Speed Blower relay and it was hidden from easy sight. I had to unravel a little electrical tape and found that it was the connector with cables goint to the starter and for the ground going to the engine block (bell housing). It was not in plain sight and I finally was able to get a peek at the back side finding the connector totally fried around the ground. So my next challenge is to somehow work in this space to build a new connector for the ground. Some of the wire wrapping is melted on the ground going to the block - about 2 inches - I am sure this will be fun.

I thank you for all your patience and guidance. I just had to follow the wiring and until now was in the wrong batch. Persistence wins!

"Any nation that expects to be ignorant and free in a state of civilization, expects what never was and never will be!"

- Thomas Jefferson

Thank you!
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Old 09-13-2007, 07:44 PM
 
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