A/C ?s
Thread Starter
Burning Brakes
Joined: Jul 2009
Posts: 1,132
Likes: 14
From: A town SC
A/C ?s
Ok, so im getting ready to start the air conditioning rebuild, renew, process, its an 81 with BB and has the smallblock serpentine conversion with the R4 compressor. My question is I know some of the GM stuff in the 80s had crappy air from the factory,so that being said anyone have suggestions on what to modify, hop up,or just plain convert over to some thing else. I want cold air, and want it to damn near give me frost bite! I have pulled the system apart and from what ive seen its fairly clean, the orphice was almost new looking. Although the air hasnt worked in probably 20 years. I do intend on using the R4 compressor as its a new delco unit. So if you have a suggestion on any improvement of the stock set up I would love to see it. Also if my expectations of the stock system is over the top, give me suggestions on aftermarket pieces, keep in mind I have to retain the R4 becuase of assesory drive conversion. Thanks in advance to all that respond...
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Well if your going with R134 I would swap out the condensor to a Paralell flow unit, it makes the system more efficient. It will require a different orifice, I don't recall the size. FLush the system well, add in a new drier new oil and charge it up. Did you pull and clean up the evaporator as part of your rebuild?
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
I second the Parallel flow condenser recommendation. It makes a big difference on our cars as we are "airflow challenged".
Of course, don't forget the inside part of the system. Make sure all the seals are good. You may want to upgrade the blower motor to a C4 model (more flow).
As for your expectations, you should expect vent temps on a 90F day to be in the mid-40's, low 40's if you're lucky. It won't give you frost bite, but it should be able to keep you comfortable even on a hot day.
Of course, don't forget the inside part of the system. Make sure all the seals are good. You may want to upgrade the blower motor to a C4 model (more flow).
As for your expectations, you should expect vent temps on a 90F day to be in the mid-40's, low 40's if you're lucky. It won't give you frost bite, but it should be able to keep you comfortable even on a hot day.
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
I rebuilt my AC system 5 years ago with all NEW parts, but stayed OEM in type. No reman stuff. But I still was not happy with it when done. Next came the Reflectix treatment under the carpet which required pulling part of the dash. So I went ahead & pulled the whole dash out *(while I was at it .... ya know how that goes)* ...
I then re-sealed the entire system. All new foam seals front to back & duct taped areas where I was not happy with fitment. Reflectix on the floor, new carpet, & then reinstalled my dash.
Ever since then, I've been happy with the AC. Yea I wish at times it still had MORE airflow, it's fine the way it is for most of my driving. I don't drive it on REAL HOT days, and on cool days the tops are off. So I don't use the AC that much but when I do, it's a lot better than it used to be. It keeps the wife & I both cool.
So yea, reseal the air box and kill any air leaks found. If you can see daylight, air is leaking. But don't forget to insulate the cockpit too. The AC is fighting a losing battle if the exhaust heat under your feet is radiating heat upward into the cabin.
I then re-sealed the entire system. All new foam seals front to back & duct taped areas where I was not happy with fitment. Reflectix on the floor, new carpet, & then reinstalled my dash.
Ever since then, I've been happy with the AC. Yea I wish at times it still had MORE airflow, it's fine the way it is for most of my driving. I don't drive it on REAL HOT days, and on cool days the tops are off. So I don't use the AC that much but when I do, it's a lot better than it used to be. It keeps the wife & I both cool.
So yea, reseal the air box and kill any air leaks found. If you can see daylight, air is leaking. But don't forget to insulate the cockpit too. The AC is fighting a losing battle if the exhaust heat under your feet is radiating heat upward into the cabin.
Advanced
Joined: Oct 2007
Posts: 59
Likes: 0
I agree with SanDiego insulate the floor, dash ect........My wife actually complained her feet were cold the other day with the A/C on, it was a hot day to..........never thought I would have that problem in a C3.
I sealed the entire heat/AC duct system and insulated the entire interior of the car with a foil backed insulating material......Worth all the trouble of for sure.
Good luck
I sealed the entire heat/AC duct system and insulated the entire interior of the car with a foil backed insulating material......Worth all the trouble of for sure.
Good luck
Thread Starter
Burning Brakes
Joined: Jul 2009
Posts: 1,132
Likes: 14
From: A town SC
The reflectics treatment is already done. So im ahead on that one. As for as the exhaust goes, I just purchased a set of BB headers that are ceramic coated( Thanks Warsurfer). Im in question on the c4 fan thing, would be interested in some details on that one, as i have heard bits and pieces but no thourough step by step modification
.Have thought of header rapping exhaust past the tail of trans to keep my **** cool
.I will be using the self stic heat barrier on the outside of the a/c box aswell. The duct tape on the vents is a good idea/will be doing that soon, so thanks to all that suggested it. Would finding an R4 compressor with smaller diameter pulley help, seems to me if i did it would up the rpms over the current one i have? I noticed my 3500 dually has the same compressor with at least 1/2 inch smaller pully/clutch. Also someone informed me that the low pressure switch was adjustable to a point,that i could gauge it and turn a screw on the switch that would delay the compressor low limit kickout? Thanks for all replies as this is my first corvette and all info greatly appreciated.
.Have thought of header rapping exhaust past the tail of trans to keep my **** cool.I will be using the self stic heat barrier on the outside of the a/c box aswell. The duct tape on the vents is a good idea/will be doing that soon, so thanks to all that suggested it. Would finding an R4 compressor with smaller diameter pulley help, seems to me if i did it would up the rpms over the current one i have? I noticed my 3500 dually has the same compressor with at least 1/2 inch smaller pully/clutch. Also someone informed me that the low pressure switch was adjustable to a point,that i could gauge it and turn a screw on the switch that would delay the compressor low limit kickout? Thanks for all replies as this is my first corvette and all info greatly appreciated.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Also check to see that the [rear] hood seal is present and actually seals to the inner rim of the hood opening. Put some Play-Doh or clay in some areas on that juncture to see what gap exists. If that seal is very old, it has taken a set in the collapsed position and is letting hot engine compartment air escape directly into the interior fresh air duct under the right side cowl area. This really 'kills' the work the A/C system is trying to do.
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