AC experts need your help

[rfuerst911sc]

I have posted before on my intended upgrades for my AC in my 83SC.I have a Sanden compressor and I am adding a huge underbelly condensor and removing the engine lid condensor.I am planning on adding another condensor either in the rear fender or the front fender,my question is if I add one in the front fender does it matter if I plumb that one before or after the oem front condensor?The additional condensor will have a fan on it,I'm thinking the oem front condensor may not be that efficient and I'm thinking the additional condensor with fan should be the last condensor that the refrigerant passes thru before entering the receiver/dryer and then the evaporator,does it matter?Thanks..................Rick

[Jim Sims]

It is recommended to have a fan cooled condenser immediately downstream of the compressor to keep high side refrigerant pressures under control and aid in the charging of the system. The underbody "static" condensers work somewhat standing still but require air flow under the car to be the most effective; if you're creeping along in traffic on top of hot pavement or are standing still trying to charge the system you will likely have problems in going directly to an underbody condenser. It would be best to leave the OEM rear deck lid condenser in place or install the largest possible fan cooled condenser in a rear fender. Then lead the refrigerant from one of these condensers to the underbody "static" condenser. Each condenser helps but for a condenser to be effective air has to flow over it; either by forced (fan or car movement) or natural convection ("static"). Cheers, Jim

[rfuerst911sc]

Thanks Jim so if I understand you correctly because I have removed my oem rear condensor I should add a fan/condensor in the rear fender and have that be the first condensor after the compressor,then plumb to the underbelly condensor then plumb to the front condensor,then receiver/dryer,then evaporator and then back to the compressor?

[turbo6bar]

I never took thermodynamics, but I believe you want the most efficient cooler first in line. This will give you the greatest temperature/pressure reduction. Am I wrong????
jurgen

[Jim Sims]

rfuerst911SC,

That's what I'd do if you insist on discarding the hatch condenser but see below.

"but I believe you want the most efficient cooler first in line."

Yep, but what will be more efficient? A large static condenser stuck under the car depending upon natural convection with the upward buoyant air flow blocked by the car bottom or a rear engine hatch mounted condenser cooled by air being inducted in by the engine fan or a much smaller fan cooled wheel well model? I'd replace the OEM engine hatch condenser with a modern triple layer engine hatch condenser with o-ring fittings. It will likely be a lot easier and more durable than trying to rig up something significant in a wheel well (and probably less expensive in the end).

See this thread for info on a modern deck lid condenser and info on hoses and subcoolers:
Barrier vs Non-Barrier A/C hoses

Jim

[rfuerst911sc]

Thanks for the replies,I believe I am going with a rear mounted fan assisted condensor in the rear wheelwell then to the underbelly unit.I am planning on staying with R12.Jim in one of your earlier posts you said you mounted an additional fan behind the passenger floor board to increase flow over the evaporator,I have been thinking about doing the same thing,can you provide any details on this?What fan,how did you mount it,where did you wire it to etc.?From the 2 holes in the bottom of the smugglers box I assume air is drawn into the box from openings behind the wood floor board covers on both the drivers side and passenger,the evap. fan draws the air up thru the evaporator then out the top to the passenger compartment,is that correct?I am planning on removing the evaporator and cleaning the unit,oiling the fan and repairing/replacing any gasket material that needs it.Also going to replace the expansion valve,is there an expansion valve available that fits the condensor but has a oring fitting for the hose?Sorry for all the questions but I want to get this right the first time.

[derkpitt]

ck this out,
A/C work, Evap box

I'm all stock and my a/c is cold in aug. here in atl.