Solution to diminished AC performance after evaporator core replacement - ZR-1 Net Registry Forums

GOLDCYLON · 05-15-2014

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.

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.

VetteMed · 05-15-2014

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

GOLDCYLON · 05-15-2014

Quote:

Originally Posted by VetteMed

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

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

mike100 · 05-15-2014

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.

VetteMed · 05-15-2014

Quote:

Originally Posted by GOLDCYLON

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

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

Dynomite · 05-15-2014

Quote:

Originally Posted by VetteMed

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

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

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

GOLDCYLON · 07-19-2020

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

Subfixer · 07-20-2020

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.

Erik · 07-21-2020

Quote:

Originally Posted by GOLDCYLON

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

Thank you, sir! Very useful info.

GOLDCYLON · 07-27-2020

Quote:

Originally Posted by Subfixer

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.

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.

05-15-2014	#2
VetteMed Join Date: Mar 2009 Location: Ocala, FL Posts: 1,827	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. __________________ No fun cars :( 1991 ZR-1 #302 White/Gray (sold) 1991 ZR-1 #1147 Red/Saddle (sold) Last edited by GOLDCYLON; 05-15-2014 at 10:11 PM.

05-15-2014	#4
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,802	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.

07-19-2020	#7
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,152	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 __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V

07-20-2020	#8
Subfixer Join Date: Sep 2018 Location: Groton, CT Posts: 359	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. __________________ 1992 ZR1 #442, 2 tops, White, White, Haibeck 415, 3.90 gear, Coilovers 2018 Audi RS5, 2.9 V6 Twin Turbo, Auto, Black, Black 2021 Audi Q3, 2.0T, 8 spd Tiptronic, Navarro Blue metallic, Pearl Beige

05-15-2014	#1
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,152	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. 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. __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V Last edited by GOLDCYLON; 05-15-2014 at 10:15 PM.