Eureka! My air conditioning works!
I am posting this note to close out the numerous postings I have made in this tech discussion archive over the past two years. Copied far below is my last posting from July 3, 2006 that briefly describes the symptoms.
Please note my comments in the next to last paragraph regarding the idler pulley. I replaced the idler pulley this past Sunday as it was becoming increasingly more noisey. It sounded just like the AC Compressor noise (Duh!). When I finished the job, I reconnected the AC Compressor, and it worked! It always did but sounded like a screaming banshee. Let me tell you, replacing this pulley on a C3 Big Block with Power Steering, A.I.R., and other associated belts is a real P.I.T.A. It was worth the aggravation.
It is also important to note that the day before was spent on first getting ambient air temperature to blow through the HVAC system. I had previously added insulation in the floor and this helped reduce heat transferred through the floor. However, I drove the car down to Woodard Avenue last week with the weather in the high nineties and just about baked to death after the car heated up. We stopped for an ice cream cone. Big mistake! Hoat soak into the HVAC system made the problem worse.
To achieve ambient air temperature, a few key repairs were done.
1) The hood weatherstrip did not seal against the opening allowing underhood heated air to get sucked into the plenum. This is easily tested by closing the hood on a few pieces of paper. If they pull right out... you have a problem. As a temporary repair, I placed some Home Depot 1/4 inch foam weatherstrip in the hood opening. A permanent repair is to install a new weatherstrip and properly adjust the hood.
2) Adjust the heater mode door to ensure it closes all of the way. This is pretty simple once you remove the RS of the dash. Mine was staying open about 20% of the way.
3) Ensure the fresh air plenum flapper valve is opening and closing properly. More information can be found at this site:
4) Seal EVERY seam in the plenum fresh air duct. This is accessed behind the passenger kick panel. Again, more information on this at the above site.
5) Installed hot water shut-off valves in the heater hoses.
6) Previously replaced blower motor with alternative design described in above site.
Last, sit back and drive comfortably with or without the air on. Ambient air blows through the system and my feet don't bake anymore.
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MESSAGE FROM JULY 3, 2006:
I am very interested to hear how this turns out. I have a similar problem on a 1974 Big Block. There are various postings in the archives.
The short version is the system was open when I purchased the car several years ago. I purchased a rebuilt Delco A6 Compressor and a rebuilt VIR. The system was cleaned out (by local Corvette oriented Chevrolet Dealer) and charged with R12.
What turned out to be occasional belt squeal is now a major belt squeal beginning at 2,000 RPM. I have followed many suggestions but, at this time I have removed the belt. I still have the original compressor and VIR. I'm considering sending these out for as rebuild and starting all over.
I have also noticed some continuing squeal without the AC belt. I have tried to localize the noise without success by removing other belts one at a time... AIR Pump, Alternator, Power Steering.
As you can imagine there is a lot of noise in the engine compartment on a big block car. The clutch fan makes one helluva roar. I suspect the idler pulley may be bad as a result of over torque from the ac belt. I have a new one to install... maybe this week.
I don't think this will solve the ac problem and have reconciled myself to another summer without AC.
I am posting this note to close out the numerous postings I have made in this tech discussion archive over the past two years. Copied far below is my last posting from July 3, 2006 that briefly describes the symptoms.
Please note my comments in the next to last paragraph regarding the idler pulley. I replaced the idler pulley this past Sunday as it was becoming increasingly more noisey. It sounded just like the AC Compressor noise (Duh!). When I finished the job, I reconnected the AC Compressor, and it worked! It always did but sounded like a screaming banshee. Let me tell you, replacing this pulley on a C3 Big Block with Power Steering, A.I.R., and other associated belts is a real P.I.T.A. It was worth the aggravation.
It is also important to note that the day before was spent on first getting ambient air temperature to blow through the HVAC system. I had previously added insulation in the floor and this helped reduce heat transferred through the floor. However, I drove the car down to Woodard Avenue last week with the weather in the high nineties and just about baked to death after the car heated up. We stopped for an ice cream cone. Big mistake! Hoat soak into the HVAC system made the problem worse.
To achieve ambient air temperature, a few key repairs were done.
1) The hood weatherstrip did not seal against the opening allowing underhood heated air to get sucked into the plenum. This is easily tested by closing the hood on a few pieces of paper. If they pull right out... you have a problem. As a temporary repair, I placed some Home Depot 1/4 inch foam weatherstrip in the hood opening. A permanent repair is to install a new weatherstrip and properly adjust the hood.
2) Adjust the heater mode door to ensure it closes all of the way. This is pretty simple once you remove the RS of the dash. Mine was staying open about 20% of the way.
3) Ensure the fresh air plenum flapper valve is opening and closing properly. More information can be found at this site:
4) Seal EVERY seam in the plenum fresh air duct. This is accessed behind the passenger kick panel. Again, more information on this at the above site.
5) Installed hot water shut-off valves in the heater hoses.
6) Previously replaced blower motor with alternative design described in above site.
Last, sit back and drive comfortably with or without the air on. Ambient air blows through the system and my feet don't bake anymore.
************************************
MESSAGE FROM JULY 3, 2006:
I am very interested to hear how this turns out. I have a similar problem on a 1974 Big Block. There are various postings in the archives.
The short version is the system was open when I purchased the car several years ago. I purchased a rebuilt Delco A6 Compressor and a rebuilt VIR. The system was cleaned out (by local Corvette oriented Chevrolet Dealer) and charged with R12.
What turned out to be occasional belt squeal is now a major belt squeal beginning at 2,000 RPM. I have followed many suggestions but, at this time I have removed the belt. I still have the original compressor and VIR. I'm considering sending these out for as rebuild and starting all over.
I have also noticed some continuing squeal without the AC belt. I have tried to localize the noise without success by removing other belts one at a time... AIR Pump, Alternator, Power Steering.
As you can imagine there is a lot of noise in the engine compartment on a big block car. The clutch fan makes one helluva roar. I suspect the idler pulley may be bad as a result of over torque from the ac belt. I have a new one to install... maybe this week.
I don't think this will solve the ac problem and have reconciled myself to another summer without AC.
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