1973 Factory AC issues
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Joined: Nov 2016
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1973 Factory AC issues
Hi,
Does anyone have information regarding the position of the air doors inside the heater box? I want to know what position the doors should be in based on the mode selected on the thumb wheel. It is original system using R12 refrigerant.
Over the last year the AC has lost efficiency. The air conditioning is serviced properly and has correct operating pressures. With outside temperatures of 80 degrees or less, the system cools well. Above that it does not cool so well, with duct temp of about 55 degrees. It seems as if one of the doors is blending outside air with the conditioned air even in the max cool position.
all suggestion appreciated.
thanks,
B
Does anyone have information regarding the position of the air doors inside the heater box? I want to know what position the doors should be in based on the mode selected on the thumb wheel. It is original system using R12 refrigerant.
Over the last year the AC has lost efficiency. The air conditioning is serviced properly and has correct operating pressures. With outside temperatures of 80 degrees or less, the system cools well. Above that it does not cool so well, with duct temp of about 55 degrees. It seems as if one of the doors is blending outside air with the conditioned air even in the max cool position.
all suggestion appreciated.
thanks,
B
Burning Brakes
Joined: Sep 2005
Posts: 1,050
Likes: 205
From: Lewes Delaware
Courtesy of Willcox, a forum supporting vendor, here is a link to the heater/AC operation schematic for a 1974; a 73 operates in a similar fashion.
http://repairs.willcoxcorvette.com/w...-schematic.pdf
The doors may be operating properly but not closing/opening all the way due to deteriorated seals or a rodent may have left something in there.
Other 73 owners that have worked on their heater boxes (Cavutu Steve comes to mind) recently will hopefully chime in.
Fran
http://repairs.willcoxcorvette.com/w...-schematic.pdf
The doors may be operating properly but not closing/opening all the way due to deteriorated seals or a rodent may have left something in there.
Other 73 owners that have worked on their heater boxes (Cavutu Steve comes to mind) recently will hopefully chime in.
Fran
Last edited by Blue73Shark; Nov 25, 2018 at 06:49 AM. Reason: rewording
Former Vendor
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Willcox
If you get a chance, please bump or Black Friday Sale threads on C3
https://www.corvetteforum.com/forums...tarts-now.html
https://www.corvetteforum.com/forums...tarts-now.html
https://www.corvetteforum.com/forums...tarts-now.html
Race Director
Joined: Apr 2009
Posts: 19,294
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From: Charlotte NC
And YES...this hose can come off and get plugged up. The thread below is a 1969 but it in the same area.
https://www.corvetteforum.com/forums...d-problem.html
DUB
Former Vendor
Joined: Aug 2006
Posts: 76,656
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
I'm not sure why you TTT'd this post, if you use the chart in the lower left you can see it tells you which pod has vacuum on it and in what position, it also shows you the diverter door and what position it's in in what stage? Did I miss something?
If so post back. On the down side, to do this testing you'll have to remove the heater control from the car so you can watch the vacuum select switch to see what position it's in. I've got a write up on my tech site that will help you remove the heater control if you need more info. You've got both mine and Dubs ear so post back.
Willcox
If so post back. On the down side, to do this testing you'll have to remove the heater control from the car so you can watch the vacuum select switch to see what position it's in. I've got a write up on my tech site that will help you remove the heater control if you need more info. You've got both mine and Dubs ear so post back.
Willcox
Last edited by Willcox Corvette; Nov 27, 2018 at 12:23 PM.
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Joined: Nov 2016
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Got back to it yesterday. All of the doors are moving correctly per the diagram Wilcox graciously provided.
I am thinking perhaps the VIR valve has an issue. So that raises several questions:
1) Is there a way to confirm VIR is failing in warmer outside temperatures?
2) If it is the VIR, do I go with a replacement VIR or install a VIR eliminator kit? Still running R12 and have plenty on hand.
Thanks,
B
I am thinking perhaps the VIR valve has an issue. So that raises several questions:
1) Is there a way to confirm VIR is failing in warmer outside temperatures?
2) If it is the VIR, do I go with a replacement VIR or install a VIR eliminator kit? Still running R12 and have plenty on hand.
Thanks,
B
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
I am by no means an A/C tech by trade. I know enough to be dangerous. So being able to tell you WHY it will or will not work under certain conditions is not in my wheelhouse of knowledge.
But I have replaced many VIR's and went with the VIR eliminator kit with great success on those Corvettes where the owner did not care if the car still looked original.
My A/C guy uses the 134a Freon adn R-12. It all depends on factors of potential leaking where the cost of R-12 is much higher than the 134a....but I know you can more than likely use the R-12.
In the thread linked to you below. On Jims system on his 1974 when I installed the VIR eliminator kit this is what happened and thankfully it was charged up with 134a Freon. I corrected this problem and now this O-ring does not nor CANNOT ever come out. Look at the photo in POST#10
https://www.corvetteforum.com/forums...-leak-wtf.html
Jim can tell you that his A/C system runs so cold...from his own words...he an sell ice cream out of his car on a hot summer day. Granted all new parts were installed for the condenser to evap core and a compressor rebuilt by Dominic and new hoses. And yes his car also has the twin SPAL electric fans also.
DUB
But I have replaced many VIR's and went with the VIR eliminator kit with great success on those Corvettes where the owner did not care if the car still looked original.
My A/C guy uses the 134a Freon adn R-12. It all depends on factors of potential leaking where the cost of R-12 is much higher than the 134a....but I know you can more than likely use the R-12.
In the thread linked to you below. On Jims system on his 1974 when I installed the VIR eliminator kit this is what happened and thankfully it was charged up with 134a Freon. I corrected this problem and now this O-ring does not nor CANNOT ever come out. Look at the photo in POST#10
https://www.corvetteforum.com/forums...-leak-wtf.html
Jim can tell you that his A/C system runs so cold...from his own words...he an sell ice cream out of his car on a hot summer day. Granted all new parts were installed for the condenser to evap core and a compressor rebuilt by Dominic and new hoses. And yes his car also has the twin SPAL electric fans also.
DUB