Are there any good publications out on trouble shooting C3 A/C systems.
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Re: C3 Air Conditioning
I hope that someone will have a answer, I need a trouble shooting guide also. -
Re: C3 Air Conditioning
tell us whats wrongComment
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Re: C3 Air Conditioning
Blower motor will not come on. Are there any common problems,switch,relay?Comment
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Re: C3 Air Conditioning
the same for me, blower will not come on makes a buzzing sound? under the pass side dash.Comment
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Re: C3 Air Conditioning
I'll try not to re-state the obvious... but have you followed the diagnosis process in the Chevrolet Chassis Service Guide (Shop Manual)? There is also a publication called "Air Conditioning Strategies for the 63-82 Corvette" by Michael J. Davis. I think you can get both at the NCRS on-line store or almost all of the Corvette mail order outlets. Amazon probably has it also.
I would also recomend you take a look at this web site. AC problems are multi-faceted on Corvettes.
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Re: C3 Air Conditioning
Jim I don't know what year your C3 is. You posted that your blower motor will not work. Under the hood there is a inline fuse for the blower motor on air conditioned Corvettes. My 70 has it, don't know when it started or stopped. this is a size 30 fuse if I remember correctly. This is the first place I would look with the information you have given.Comment
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Re: C3 Air Conditioning
Jim forgot to mention in the above post, the inline fuse on my 70 comes from the horn relay and is located near the brake master cylinder and believe it is an heavy duty orange type wire with a clear plastic fuse holder.Comment
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Re: C3 Air Conditioning
Jim - my 74 has the same design.....so at least it went that far....CraigComment
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Re: C3 Air Conditioning
If I remember correctly, this fused feed may only run the blower in the high speed position....controlled by the speed switch in the console. The other speeds have a resitive bridge in the blower housing used to drop the voltage for lower speed settings. I vaguely recall once my blower would not operate on high only, and it was this fuse. Other speeds worked. This would show for sure in the chassis service manual wiring diagram, I am only going from memory and this car is apart so not provable CraigComment
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Might be two different problems here...
In the case of the original post (Ellis), we aren't told what year C3 we're working on. In the Sharpton situation, I speculate it's a '71 Corvette from his board profile. The 1971 poses a 'special' condition because that was a one-year only design incorporating a pair of logic relays behind the RH lower dash to work in conjunction with the '71 Combined Emission Control system and that's probably what Sharpton hears as the 'buzzing' sound he reports.
For the '71, the extra features of the CEC A/C control are shown in the C60 option section of the AIM (Assembly Instruction Manual) and repeated in the air conditioning section of the CSM (Chassis Service Manual) where wiring diagrams specific to the A/C option are provided. Essentially, two smart relays were mounted behind the passenger side lower dash to over-ride the center console A/C controls.
During engine shut-down, these relays acted to: (1) deny power to the fan blower motor and (2) FORCE power to the A/C compressor clutch. Together, they acted to add 'drag' to the engine to thwart run-on (engage compressor regardless of A/C control setting) and prevent the blower from running (so the driver/occupant wasn't 'startled' by the blower coming on automatically for a few seconds in lock-step to engine shut-down).
The relay pair was mounted to the outside wall of the fiberglass Harrison air box and the mounting tabs required connection to a discrete ground wire in the harness (circular lug) as depicted in the AIM regarding the installation of these relays. If the ground is improperly connected or the relay(s) are 'fried' you can expect erratic operation of both the blower motor and/or the compressor.
Common to other years of Shark A/C equipped cars, you'll find the extra wiring paths associated with A/C documented in both the AIM and the CSM under air conditioning (C60 section). Basically, the blower fan's three lower speeds are controlled by the center console switch and protected at the main fuse block where the A/C harness plugs in as an option. The blower fan's high/max speed mode is controlled by the center console switch but protected and powered by a discrete power lead attached to the side terminal of the horn relay in the engine compartment using a dedicated in-line fuse.
Often, we see 'Jeckyl/Hyde' situations where the blower works at low fan speeds but doesn't work in its high speed setting. This is typically the result of either the in-line fuse in the separate hi-speed power circuit being blown OR the blower relay (mounted on the engine compartment side of the Harrison air box) being defective....
Typically, the CSM book gives a reasonably thorough dissertation on troubleshooting distinguishing the subtle differences between the Corvette, Chevy, Nova, Camaro and Chevelle systems. I'd start by buying and reading the CSM book for your particular year of Corvette....Comment
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Re: Might be two different problems here...
please, call me Lyndon, are Kelly.Comment
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Re: C3 Air Conditioning
I'm sorry I didn't state the year of the car in my previous post,but it is a
1969 convertible.Comment
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Re: C3 Air Conditioning
Craig you are correct on the fuse being for the high speed blower position of the fan blower switch. The other three speeds will work without the high speed fuse in the circuit. Just for confirmation, should of looked the other night, the wire on my 70 comes from the horn relay as a red wire to the clear plastic fuse holder, the wire at the other end of the fuse holder is orange.Comment
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