Solution to diminished AC performance after evaporator core replacement
 

Many thanks to Vettemed, I have created this thread to be a standalone thread as a searchable solution. Folks take note of Andrews post #318 in his update of his hi miler ZR-1 project. If you are having dimished AC performance after replacing the evaporator core. Last summer my car in my opinion was not cooling down as much as it used to do in heavy AC load conditions in the 118-122 dog days of summer in Arizona. It always used to be a lot colder from my memory and since reparing the AC a year or so ago with all new parts I just could not figure out what was going on. I remembered this post up as Andrew was having the same problems. I put this on the long list of projects I wanted to complete this winter. I missed it.. however, and it didnt make it to the list last winter, Tuesday of this week was a uber rare Santa Ana winds fed blustery day here in AZ and the evening temps in the garage were in the 70s and I said well... now or never. I had my evaporator core replaced while I was TDY at work so I never saw the original unit that was removed. Long story short I had the exact same gap on the left side of the heater core that Andrew has pictured in picture #1 of post #318. So I fed gray foam material, the kind used used to protect guns and hard drives into that vertical slot. Walla.. in 100 degree temps yesterday the AC was spitting out 46 Degree air.
http://i680.photobucket.com/albums/v...t/IMG_0469.jpg
This view is what you might see if you pull the blower motor and look towards the evaporator core. See that vertical gap? it should not be there. As Andrew stated in his post either the replacement evaporator core is shorter than stock or it is factory foamed in on that side. Make sure you or your installer is aware of this issue so they can address it at time of replacement. Andrew was 100% correct with the gap hot air was bypassed into the system and mixing into the cooler air.

Re: Solution to diminished AC performance after evaporator core replacement
 

Daryll, good idea to make this more easily searchable. However, one correction, this is the evaporator core, not the heater core. :)

Re: Solution to diminished AC performance after evaporator core replacement
 

Duh I knew that lol and I updated it. Wish you had your car back bro

Re: Solution to diminished AC performance after evaporator core replacement
 

Airflow from small pressure differentials is an amazing phenomenon. So many air-cooled VW's back in the day ran hot from a bad engine seal separating the top half from the bottom which allowed for the cool air to be ducted to the cylinder fins etc.

Also same deal on some air cooled electric motor drives we used to make. You can just about double the useful cfm through a heat exchanger with the leaks eliminated.

Re: Solution to diminished AC performance after heater core replacement
 

Maybe someday it'll pop up for sale again...

Re: Solution to diminished AC performance after evaporator core replacement
 

This is what got Daryll's attention Solution to Evaporator Core Leaks

This has now been "linked" in -Solutions- (Air Conditioner and Heater) ;)

Re: Solution to diminished AC performance after evaporator core replacement
 

POSTING THIS UP again as we are in the dog days of summer again ! GC

Re: Solution to diminished AC performance after evaporator core replacement
 

That is the gap I was explaining in the other post about fan speed.
The original seal fills that gap.
Since the seal is glued to the evaporator, many get tossed (and not replaced) by unknowing techs.
Also missing in the photo is the debris screen that sits between the fan and evaporator.

Re: Solution to diminished AC performance after evaporator core replacement
 

Thank you, sir! Very useful info.

Re: Solution to diminished AC performance after evaporator core replacement
 

Yep gotta pic of the Debris screen sub fixer ? I have had 3 heater cores replaced in 3 different C4s. Nine of em Had a screen and all had that damn gap. Leaves me to believe all three were replaced once before they came into my care.