AC Upgrade-Custom Evaporator?

'69 2800cs

'69 2800cs

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I'm putting together an AC upgrade using a number of the great threads on the board here. Rotary compressor, big condensor, new lines, etc. I'll post details when done.

The one remaining stock piece I planned to reuse was the evaporator. I'm cleaning it and replacing the expansion valve, but I wonder if now is the time to upgrade this part.

-In your opinion, is there a meaningful performance upgrade by replacing the evaporator?

-Is there a drop in option out there? (I do know Rob Siegel had a custom evaporator made and posted his source a while back)

thanks,
 
Unless you can increase the airflow with more vents or higher output fan I am not sure there is much more to be gained here. After my upgrade, the air is ice cold coming out of the evaporator at all fan speeds and it will freeze up if you have the temp knob cranked too high. I am not sure if a larger coil will help or freeze up quicker, I think the latter because there is not enough airflow to prevent that.

But at some point my evap coil will give it up so if you beef up that part like Rob did please post the retrofit.

The heater bypass will also improve things dramatically.
 
The thought of even more and even colder air blowing on my right elbow and right knee only
Makes me afraid.
 
Very true, but now some of this air can now be diverted to a passenger instead of them suffocating.

sfdon said:
The thought of even more and even colder air blowing on my right elbow and right knee only
Makes me afraid.
Click to expand...
 
Thanks Steve...stock evaporator it is. I've thought about increasing the air flow with additional vents and there are some spots to do it. One step at a time though, just getting all this stuff to work together will take some effort.

I tried the bypass valve but couldn't make it fit with my downdraft webers, so I did a simple bypass. I also have the trans out and the tunnel is getting insulated. Next up is window tint.

I'm committed to using this car in the 95 degree, 90 percent humidity!
 
If you have the tranny out consider putting a tube up into the evaporator drain hole (but not too far in - just to the edge of the bottom inside of the case so it doesn't pool in the evap) and have it protrude out of the tunnel about 1/4 inch or so. This will keep the condensate from collecting in the bodywork. I forgot which size tube i used, but you should be able to find one that fits snug into the evap. Put a little epoxy on the end to hold it in permanently. leave the gap between the tube and the bodywork just in case.


'69 2800cs said:
Thanks Steve...stock evaporator it is. I've thought about increasing the air flow with additional vents and there are some spots to do it. One step at a time though, just getting all this stuff to work together will take some effort.

I tried the bypass valve but couldn't make it fit with my downdraft webers, so I did a simple bypass. I also have the trans out and the tunnel is getting insulated. Next up is window tint.

I'm committed to using this car in the 95 degree, 90 percent humidity!
Click to expand...
 
'69 2800cs said:
Thanks Steve...stock evaporator it is. I've thought about increasing the air flow with additional vents and there are some spots to do it. One step at a time though, just getting all this stuff to work together will take some effort.

I tried the bypass valve but couldn't make it fit with my downdraft webers, so I did a simple bypass. I also have the trans out and the tunnel is getting insulated. Next up is window tint.

I'm committed to using this car in the 95 degree, 90 percent humidity!
Click to expand...

What did you use to insulate the tunnel?
 
The Custom Evaporator Core... meh

I was talked into the custom evaporator core setup by Bob Pogge at ICE air nearly 20 years ago as part of the whole "oh god R134a is coming the sky is falling" thing that was going on. It was a neat idea -- a three-row evaporator core that is exactly the same dimension as the stock 2-row core, fits in the same evaporator housing, and gives R134a a fighting chance -- but I don't know how much of a difference it made. As I discuss in the book, the single longest chapter of which is on air conditioning, the a/c in the E9 works very well unless it's snot-hot and disgustingly humid out, in which case it maxes out. I've tinted the windows, I've shut off the flow of coolant to the heater core, and still have the same result.

When I redid the a/c in my '72 2002tii, I stuck with R12, and the a/c in that car gets cold enough to hang slaughtered beef.

I'm not an a/c technician, but my advice, in decreasing order of importance is:

1) Stick with R12
2) Rotary compressor
3) Install the biggest parallel condenser you can stuff into the nose of the car.
4) If you drive in hot traffic, install a fan on that condenser so powerful it'll suck dogs off the sidewalk.
5) Shut off the flow of coolant to the heater core.

Not sure where "make sure that, when the fresh air vents are closed, they're not letting in fresh air (degraded foam seals)" falls because I haven't done it yet.

Then, everything else. Yes, obviously the fan in the evaporator assembly has to spin well.

If anyone lives in a snot-hot climate and has bone-chilling R134a-based a/c, more power to you, but I ain't there yet.

--Rob
 
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The insulation I bought was from Summit Racing or one of the other hot rod shops.

It's a very thin aluminum sheet, easily bendable, backed by some sort of high tech insulation, with a stick on back. It was expensive-I think $200 for a 4x4 sheet.

I've bypassed the heater core. Thing is-the tunnel still gets really, really hot. It may be, at least in my car, that the exhaust heat in the tunnel is more problematic than the heater core.

thanks for all the ideas...I will stick with R12.
 
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