Dash is pulled...couple questions on Core and Evap
10-07-2019, 12:37 PM
#1
Junior Member
Thread Starter
Dash is pulled...couple questions on Core and Evap
Thanks to this forum and a few others I was able to get the dash pulled and the heater box removed on my 96 XJ. I'm not too worried about putting the dash back together but I am worried about having the heater core and Ac evap correctly installed.
When I pulled the evap I noticed that there was a copper tube inserted into the core of the evap. What does this do and should I replace this as well before reinstalling?
Any other advice while re-installing the heater box? I've had nightmares that I have everything put together and my heater doesn't work and I have to tear it all apart again.
Also, if anyone is considering doing this job feel free to ask me some questions while it's still fresh in my mind. On a scale of 1 to 10 for mechanical ability, I'd say I'm about a 5 so this job can be done by most folks if I can do it.
When I pulled the evap I noticed that there was a copper tube inserted into the core of the evap. What does this do and should I replace this as well before reinstalling?
Any other advice while re-installing the heater box? I've had nightmares that I have everything put together and my heater doesn't work and I have to tear it all apart again.
Also, if anyone is considering doing this job feel free to ask me some questions while it's still fresh in my mind. On a scale of 1 to 10 for mechanical ability, I'd say I'm about a 5 so this job can be done by most folks if I can do it.
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318SixPack (10-07-2019)
10-07-2019, 02:49 PM
#2
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Year: 2001
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I be leave that the copper tube is the thermostat tube it needs to be reinstalled in to the evaporator core to be able to stop the evap from freezing .
10-07-2019, 04:50 PM
#3
Junior Member
Thread Starter
Thanks for the info on this. Hopefully these things don't go bad because if it does it looks like the whole dash would have to come out again.
10-07-2019, 10:43 PM
#5
Senior Member
It is called the Thermistor. New cores do not have provisions to stick it in them like the old ones.
Also DO NOT just try to pull it out from the plastic HVAC housing. It will come apart on you, and the Factory MOPAR unit is not available.
There was a guy on Fleabay, that had a few RANCOR style units for sale. They will connect to your plugs, and are basically the same unit, however they will be a little off (few degrees) from the MOPAR unit.
If you do by chance break the thermistor (thermostat) I still have the factory box with the part number on it.
Look on my build thread to see how I installed it with the new evap core.
Also DO NOT just try to pull it out from the plastic HVAC housing. It will come apart on you, and the Factory MOPAR unit is not available.
There was a guy on Fleabay, that had a few RANCOR style units for sale. They will connect to your plugs, and are basically the same unit, however they will be a little off (few degrees) from the MOPAR unit.
If you do by chance break the thermistor (thermostat) I still have the factory box with the part number on it.
Look on my build thread to see how I installed it with the new evap core.
10-08-2019, 08:55 AM
#6
Senior Member
Couple tips:
1) Make sure all the foam on the doors is in good shape. It tends to dry-rot after this many years and exposure to heat. If it's even CLOSE to that, get some replacement high-temp foam from McMaster Carr. That's what I did.
2) Make sure it's sealed well, use RTV or foam in a couple corners where lines go in/out ...if need be.
3) I seem to have rodents get in some vehicles (not so much my Jeep though) ...so what I did was put a 1/4" mesh screen on my defrost inlet to keep those ba$tards from getting down the ductwork. When not in use, if you have it off ...if I recall ALL doors would be closed. So if you don't drive it in a while, make sure all vent doors are in the 'closed position'.
4) I went with a copper heater core (if you can find one). If you go with aluminum ..I always tell people to replace the anti-freeze with new. B/c old anti-freeze can become high in pH due to the sensors in the coolant ...and just general age and maybe electrostatic discharge ..who knows. But anyway, the result is, low pH coolant is highly corrosive to aluminum and your heater core would become an anode ...meaning it's a sacrificial metal. So is your water pump to ..but it happens to be over 1/8" thick metal ...your heater core is paper thin. Ideal pH would be around high 8's or low 9's. Nobody ever pays attention to this so I'm not sure why I even mention it anymore. I used to see guy's new $50k aluminum boilers rot out in a couple years back in the day . Copper is a lot more pH tolerant, that's why it's ideal. But they're hard to find.
5) Make sure the coolant bottle is all good and the hoses in that area. The bottles tend to get brittle and crack at the bottom outlet hose region after all these years. You can get aftermarket.
6) You might pour out the oil out of your evap core and put it in the new one. Or add the appropriate amt of new oil in your system. Make sure all the o-rings are good. You need to pull a deep-vacuum on the system 3x times before re-charging.
Good luck!
1) Make sure all the foam on the doors is in good shape. It tends to dry-rot after this many years and exposure to heat. If it's even CLOSE to that, get some replacement high-temp foam from McMaster Carr. That's what I did.
2) Make sure it's sealed well, use RTV or foam in a couple corners where lines go in/out ...if need be.
3) I seem to have rodents get in some vehicles (not so much my Jeep though) ...so what I did was put a 1/4" mesh screen on my defrost inlet to keep those ba$tards from getting down the ductwork. When not in use, if you have it off ...if I recall ALL doors would be closed. So if you don't drive it in a while, make sure all vent doors are in the 'closed position'.
4) I went with a copper heater core (if you can find one). If you go with aluminum ..I always tell people to replace the anti-freeze with new. B/c old anti-freeze can become high in pH due to the sensors in the coolant ...and just general age and maybe electrostatic discharge ..who knows. But anyway, the result is, low pH coolant is highly corrosive to aluminum and your heater core would become an anode ...meaning it's a sacrificial metal. So is your water pump to ..but it happens to be over 1/8" thick metal ...your heater core is paper thin. Ideal pH would be around high 8's or low 9's. Nobody ever pays attention to this so I'm not sure why I even mention it anymore. I used to see guy's new $50k aluminum boilers rot out in a couple years back in the day . Copper is a lot more pH tolerant, that's why it's ideal. But they're hard to find.
5) Make sure the coolant bottle is all good and the hoses in that area. The bottles tend to get brittle and crack at the bottom outlet hose region after all these years. You can get aftermarket.
6) You might pour out the oil out of your evap core and put it in the new one. Or add the appropriate amt of new oil in your system. Make sure all the o-rings are good. You need to pull a deep-vacuum on the system 3x times before re-charging.
Good luck!
Last edited by Jeepwalker; 10-08-2019 at 09:01 AM.
10-08-2019, 05:51 PM
#7
Junior Member
Thread Starter
Couple tips:
1) Make sure all the foam on the doors is in good shape. It tends to dry-rot after this many years and exposure to heat. If it's even CLOSE to that, get some replacement high-temp foam from McMaster Carr. That's what I did.
2) Make sure it's sealed well, use RTV or foam in a couple corners where lines go in/out ...if need be.
3) I seem to have rodents get in some vehicles (not so much my Jeep though) ...so what I did was put a 1/4" mesh screen on my defrost inlet to keep those ba$tards from getting down the ductwork. When not in use, if you have it off ...if I recall ALL doors would be closed. So if you don't drive it in a while, make sure all vent doors are in the 'closed position'.
4) I went with a copper heater core (if you can find one). If you go with aluminum ..I always tell people to replace the anti-freeze with new. B/c old anti-freeze can become high in pH due to the sensors in the coolant ...and just general age and maybe electrostatic discharge ..who knows. But anyway, the result is, low pH coolant is highly corrosive to aluminum and your heater core would become an anode ...meaning it's a sacrificial metal. So is your water pump to ..but it happens to be over 1/8" thick metal ...your heater core is paper thin. Ideal pH would be around high 8's or low 9's. Nobody ever pays attention to this so I'm not sure why I even mention it anymore. I used to see guy's new $50k aluminum boilers rot out in a couple years back in the day . Copper is a lot more pH tolerant, that's why it's ideal. But they're hard to find.
5) Make sure the coolant bottle is all good and the hoses in that area. The bottles tend to get brittle and crack at the bottom outlet hose region after all these years. You can get aftermarket.
6) You might pour out the oil out of your evap core and put it in the new one. Or add the appropriate amt of new oil in your system. Make sure all the o-rings are good. You need to pull a deep-vacuum on the system 3x times before re-charging.
Good luck!
1) Make sure all the foam on the doors is in good shape. It tends to dry-rot after this many years and exposure to heat. If it's even CLOSE to that, get some replacement high-temp foam from McMaster Carr. That's what I did.
2) Make sure it's sealed well, use RTV or foam in a couple corners where lines go in/out ...if need be.
3) I seem to have rodents get in some vehicles (not so much my Jeep though) ...so what I did was put a 1/4" mesh screen on my defrost inlet to keep those ba$tards from getting down the ductwork. When not in use, if you have it off ...if I recall ALL doors would be closed. So if you don't drive it in a while, make sure all vent doors are in the 'closed position'.
4) I went with a copper heater core (if you can find one). If you go with aluminum ..I always tell people to replace the anti-freeze with new. B/c old anti-freeze can become high in pH due to the sensors in the coolant ...and just general age and maybe electrostatic discharge ..who knows. But anyway, the result is, low pH coolant is highly corrosive to aluminum and your heater core would become an anode ...meaning it's a sacrificial metal. So is your water pump to ..but it happens to be over 1/8" thick metal ...your heater core is paper thin. Ideal pH would be around high 8's or low 9's. Nobody ever pays attention to this so I'm not sure why I even mention it anymore. I used to see guy's new $50k aluminum boilers rot out in a couple years back in the day . Copper is a lot more pH tolerant, that's why it's ideal. But they're hard to find.
5) Make sure the coolant bottle is all good and the hoses in that area. The bottles tend to get brittle and crack at the bottom outlet hose region after all these years. You can get aftermarket.
6) You might pour out the oil out of your evap core and put it in the new one. Or add the appropriate amt of new oil in your system. Make sure all the o-rings are good. You need to pull a deep-vacuum on the system 3x times before re-charging.
Good luck!
-I believe my new Heater Core is aluminum. I got if from NAPA because I had read they are a little better than the Autozone stuff.
-You can tell I'm new at this as I didn't know the evap core had oil in it or that I have to add it to the new one.
-The foam on the doors is brittle. Will this make a huge difference mechanically if I keep the old stuff on it?
-The coolant is pretty new, within 15k miles. Not sure that is new enough so I might just replace.
Thanks for the help, this job is getting even more involved.
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10-08-2019, 05:56 PM
#8
Junior Member
Thread Starter
It is called the Thermistor. New cores do not have provisions to stick it in them like the old ones.
Also DO NOT just try to pull it out from the plastic HVAC housing. It will come apart on you, and the Factory MOPAR unit is not available.
There was a guy on Fleabay, that had a few RANCOR style units for sale. They will connect to your plugs, and are basically the same unit, however they will be a little off (few degrees) from the MOPAR unit.
If you do by chance break the thermistor (thermostat) I still have the factory box with the part number on it.
Look on my build thread to see how I installed it with the new evap core.
Also DO NOT just try to pull it out from the plastic HVAC housing. It will come apart on you, and the Factory MOPAR unit is not available.
There was a guy on Fleabay, that had a few RANCOR style units for sale. They will connect to your plugs, and are basically the same unit, however they will be a little off (few degrees) from the MOPAR unit.
If you do by chance break the thermistor (thermostat) I still have the factory box with the part number on it.
Look on my build thread to see how I installed it with the new evap core.
When I initially pulled it out a couple of wires came out of the copper tube and it appeared they had some silicone lubricant on them. I was able to stuff them back in the copper tube hoping they will still work.
So are you saying that the evap core I'm getting delivered from Amazon won't have a recess for that Copper tube? If I install without the tube then will the evap freeze up? I'm starting to think I should have kept the original, working evap in place.
I looked at your build thread and the workaround for the thermistor looks pretty easy. One question though: Did you simply use some putty/clay to basically stick the copper tube to the fins? If so, what is the stuff you used?
Last edited by Furrydogs; 10-08-2019 at 07:53 PM.
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