Evaporator Replacement?
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
Evaporator Replacement?
During winter garage time I'm going to tackle my AC one more time.
Here's what I've done so far:
Sanden Compressor
new condenser
Dual Spals
C4 fan
insulated and sealed evap case
sealed ducts
13 v to fan
R134
Cleaned leaves, etc from evap case
Replaced heater coil
I still have low volume and inadequate cooling
So, all that's left is the evap coil.
Is there a better evap coil out there that is a better match for the Sanden, is more efficient or flows more air?
Is there a smaller heater coil that will allow more conditioned air to pass?
Any help appreciated.......
Here's what I've done so far:
Sanden Compressor
new condenser
Dual Spals
C4 fan
insulated and sealed evap case
sealed ducts
13 v to fan
R134
Cleaned leaves, etc from evap case
Replaced heater coil
I still have low volume and inadequate cooling
So, all that's left is the evap coil.
Is there a better evap coil out there that is a better match for the Sanden, is more efficient or flows more air?
Is there a smaller heater coil that will allow more conditioned air to pass?
Any help appreciated.......
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
The original a/c systems work fine on the C3's providing everything is in proper working order. Air volume, however, is generally on the low side, but your bigger fan may help that. Other problem areas regarding cooling are the rear hood seal not sealing properly and allowing engine heat into the air mix, engine heat entering thru the firewall, and a faulty heater control valve located in one of your heater hoses. You also want to make sure you have the proper 134A charge in the system which is generally 75% or so of the R12 fill. 
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
The original a/c systems work fine on the C3's providing everything is in proper working order. Air volume, however, is generally on the low side, but your bigger fan may help that. Other problem areas regarding cooling are the rear hood seal not sealing properly and allowing engine heat into the air mix, engine heat entering thru the firewall, and a faulty heater control valve located in one of your heater hoses. You also want to make sure you have the proper 134A charge in the system which is generally 75% or so of the R12 fill.
Good tips. Real hood seal in place. Firewall plugged and insulated. Manual valves installed on heatr supply and return lines. Fully charged by a pro.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
I doubt the evav. core is your problem unless it is clogged up but you say you checked it. Did you have it completely out when you checked it. When I changed mine, all the leaves and crap were at the bottom. How are your pressures? Is the tech who charged your system satisfied with them and what does he have to say about your problem? For sure something is amiss and perhaps if all else fails, take it to a good Vette tech who really knows a/c. Just so you know, my totally stock '76 blows 40 degrees at the vents and I live in South Florida. It could use more air volume, but overall it does the job quite well. I wish you luck, Will, in getting the problem solved.
Burning Brakes
Joined: Aug 2004
Posts: 856
Likes: 2
From: Tyler Texas
http://forums.corvetteforum.com/show....php?t=1715489
Read this thread. When I addressed the "radiant heat issue" after doing all the normal AC fixes--as you have done--my AC and hot air thru vent issues were all solved.
Read this thread. When I addressed the "radiant heat issue" after doing all the normal AC fixes--as you have done--my AC and hot air thru vent issues were all solved.
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Advanced
Joined: Nov 2011
Posts: 82
Likes: 0
Why change compressors?? The A-6 is 13 cu inches and probably one of the best compressors ever made. The 508 sanden is only 8 cu in. The A-6 has a internal oil pump with an oil sump. The sanden has neither. It depends on oil flow with the refrigerant to keep it alive. I have been in the mobile HVAC industry for years and seen very few cooked a-6's. Seen more locked up sanden's than I can count!!
Melting Slicks
Joined: Jul 2009
Posts: 3,264
Likes: 3
From: Vero Beach FL
Small thing perhaps but do you have the evaporator drain tube in place? If not heat from the exhaust can get into the evaporator box.
http://www.zip-corvette.com/ProductD...GR-SR&CTitle=&
http://www.zip-corvette.com/ProductD...GR-SR&CTitle=&
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
[QUOTE=Roco71;1581286921]Small thing perhaps but do you have the evaporator drain tube in place? If not heat from the exhaust can get into the evaporator box.
If this is not in place, you have a 1"+ hole in the bottom of the evap case wasting cooled air.
If this is not in place, you have a 1"+ hole in the bottom of the evap case wasting cooled air.
