replacing heater core-should I do R134? (+write-up)

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I've finally been bitten with a leaking heater core. I'm ready to dig in and probably (hopefully) have a good radiator shop fix it. There's good info on the job though no videos, If i feel like the community would benefit from one I may go ahead and do that. This thread is a write-up for the disassembly of the dash, in addition to the following:

"while I'm in there", I'm thinking of converting my A/C (which has been inop for 10+ years) to R134a. I don't know much about why it doesn't work other than when I jump the compressor clutch the air temp hardly changes. I don't want to try to source R12 only to find I can't hold it.

MODS: It seems that there's a lot of diverse opinions on weather or not the retrofit is a good idea, and how to go about it. Being that there's nothing in the FAQ's about this, My goal for this thread is to come to a consensus on how (and even when) the conversion should be done, So I hope to hear from the experts.
Assuming my system can't hold pressure, I think it's fair to say the conversion is the smart (and legal) way to go. So far it seems like I'll need to replace the following for best results:
-all 0-rings
-drier
-retrofit valve fittings for R13a
-what about the expansion valve? Is this a common wear item?

From there, the procedure seems to look something like:
-drain the system: use the jumped compressor to empty out the opened system; remove compressor and drip drain the rest
-add oil to drier and replace all the aforementioned hardware
-evacuate (apply vacuum to) the sealed system
-add new R134a freon.

If someone could chime in and confirm that I my thinking is correct to this point, we'll move on to the specifics.

Does anybody have experience with these rigs not holding pressure due to anything besides the old O-rings?

Drew
 
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g-man

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Disclaimer: Not an expert. Your thinking is sound. I replaced my...compressor, dryer, condenser and expansion valve. Pag 46 oil was added to the compressor. Some may argue not to replace all this but I just thought I should replace as much as possible. Besides being a source of a leak, old components can be a source for debris that can circulate around and damage a new compressor. Another reason to put a vacuum pump on the system before charging.

I had a problem disconnecting the condenser line on the passenger side and front of the condenser. Galvanic corrosion occurs here due to dissimilar metals. The condenser has a male aluminum fitting that goes into the dryer lines steel female. I stripped the aluminum. Luckily I was able to remove the line from the dryer and put it in a vice and using map gas melt the aluminum out of the female coupling's threads and re-use that line. May be best to put some heat on this connection if it's not cooperating to get it apart.

there is a blue knob under the glove box that is a AC amplifier control. It should be set so the AC turns on over 900 rpms and off under that. The AC compressor clutch should kick off while the engine sits at low idle. It may be necessary to pull out the choke knob a bit and let the idle come up over 1k while you fill freon.

Make sure the blue light is on and the fan is turned on high while filling. If your fan goes out on you and the blue light goes out you may have tripped an old heater circuit breaker. They tend to fail way before 30 amps when they are old. My work around was to put a 30 amp inline fuse in the heater CB

Fuse.jpeg
 
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Awesome, thanks for such useful information. In my case I'm rocking the 2fe but I'll be sure to make sure that they clutch is engaged while I fill. What are your thoughts on your AC system performance-wise post R134a?
 
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Time for an update. Between rigorous midterms, I've had some time here and there to address the issues under my dash. For anybody intimidated by this project I thought I'd include some helpful tips for disassembly.
To remove dash pad (without speaker):
-First remove the 4 screws (2 on each side) of the dash cap that hold the mirror defrost vents.
-remove glove box and gage cluster (the screws for these go through the dash pad, and with them removed you have access to the rest of what needs to be removed)
-remove radio (this gives you access to the clips)
Sorry for the crappy cell phone pics but everything circled in red is what holds the dash pad on (not including the side defrosts)
Passenger side (US):
2019-10-22 10.52.52.jpg

Drivers side (US):
2019-10-22 10.52.09.jpg

the clips, as seen from the radio slot:
2019-10-22 10.50.54.jpg
 
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When undoing the nuts, they don't technically need to come out all the way because the ears they mount to are slotted (see first pic), however, it wasn't any harder to remove them completely and I believe it simplified actually pulling the pad. Lastly, the side defroster ducting needs to be separated. I found it easiest to do this where the flexible tube meets the box-shaped section.
Slotted ears:
20191022_110310.jpg

Closer view of the clips, accessed through radio slot:
20191022_110246.jpg

What the clips clip onto:
20191022_110301.jpg

Side defroster ducting:
20191022_111607.jpg

The dash is now ready to remove. The vent balls (for lack of better term) don't need to be disconnected, and the ducting for them simply slips out of each other over the foam. alternate pulling on each clip with your arm through the radio, and gently pull the center of the pad towards the back of the car. As everyone should know, these are pretty fragile and prone to cracking so be careful during this part as well as where/how you store this piece.
 
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This rig has been in our family for a few decades now, and unfortunately we're looking to sell it. I took this as an opportunity to clean up the rats nest that resulted from the PO's trailer brakes, high school projects, aftermarket radio, EFI, and who knows what else. I've seen some horror stories of new owners here on MUD and I don't want this rig to be one of them.
20191010_163642.jpg

20191012_152913.jpg
20191012_152907.jpg

I do, however, like this little box I made from the sandwich holder and want to keep it....It just needs a little better presentation on the back side.
20191022_104316.jpg
 
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All the wires went straight to whatever, so there was no way to take out the box without either clipping the wires or unplugging them from one end or the other and unfeeding the whole thing. I have bits of a 62 harness from when I did the 2fe, so I made cuts where I'd like a plug, bundled the wires together and used an OEM plug for easy removal in the future.
20191021_225142.jpg

And a pic of the inside
20191021_225035.jpg

For anybody that's curious, this is just a Plexiglas front carved with a dremel and painted, and the label was printed from Word onto frosted paper I got from a craft store. The light is the same one as is behind the climate controls, and is on the same circuit. A light reflective paint inside the box made a big difference in the quality of back lighting. Overall I think it's a nice looking, period correct method to control all things auxiliary.
2015-02-25 21.45.48.jpg
 
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In the end, I have the original wire harness, an efi harness, and an "aftermarket stuff" harness. Each is as independent as can be from each other, both physically and functionally. Each have a separate path to the battery and only intermix for signal purposes.
 
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pulling the heater core begins with removing the AC unit. (Well that's mostly true, however there is one thread in the FAQ that shows how to just scoot it over w/out cracking the line). I wasn't concerned about doing this because the AC hasn't worked in over a decade. Temporarily jumping the compressor yielded a hardly noticeable change in air temp, so i figured the system had a leak somewhere and didn't have enough pressure. I was surprised by a very long, loud hiss when I cracked the AC line...shoot! I guess I had pressure afterall, but maybe not enough for the AC amp to be happy though? But now that I for sure have no pressure or R12, I think I'm now committed to converting to R134a. I should pick up the heater core today, and I'll talk to the shop about converting as they do cooling also.

All ducting needs to be removed, with the exception of the defrost and far drivers side vent. This is little work for a lot of gain.

From comments I've read on here, I was honestly expecting more crud. Will hit with an air compressor to clean out.
20191022_114924.jpg


These are the 3 connections that have to be undone on the AC unit. disconnecting the plug for the AC button allows you to tuck that portion of the harness out of the way.
20191022_114945.jpg

And here are the mounting points for the AC box
20191022_115027-1.jpg
 
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This is a great time to remove your blower box and inspect the cowell for rust where the air comes in. pictures on the site have made me nervous about this for a while.
To my relief, there was just clean metal and one mudwasps nest (not pictured). It's a good idea to get rid of all the leaves and crud in the cowell to make sure the drains in the fender are clear. Removing the wiper motor gives you good access to the other side.
20191022_115421-1.jpg

Removal is easy. Undo the plug at the bottom, the fresh air intake control cable, the two bolts circled below and the one circled above and to the right. This last one can be intimidating because of its location, but a long extension makes quick work of it. Keep in mind when installing that the screw doesn't have to come out all the way, toyota got our backs and slotted the little ear on the blower box so it can just slide in place.
20191022_115509-1.jpg
 
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Finally, onto the heater box. It's convenient, though not necessary, to remove the heater control box. It has one plug for the AC switch, one for the blower switch/back light, one cable for the fresh air, one to the valve at the firewall, and one for the blend door in the heater box itself. Remove all these and it's ready to be set aside, giving you nice visual and access.

Next, make the disconnections circled in red:
20191022_115235-1.jpg
 
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I had my 3fe converted to R134a about 3 years ago. I am not sure all the conversion work that was done, but it was only like 150 bucks and the cold air is friggin nice. Probably not as cold as R12 but only noticeable on the hottest of days in DC and then only when in traffic for a while.
 
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I had my 3fe converted to R134a about 3 years ago. I am not sure all the conversion work that was done, but it was only like 150 bucks and the cold air is friggin nice. Probably not as cold as R12 but only noticeable on the hottest of days in DC and then only when in traffic for a while.
That's encouraging! Did you pay the shop to do everything? and How long has it been? I'm sure the systems are similar, aside from the electrical differences
 
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By this point, the two heater lines at the firewall should be disconnected. If they don't come off easy, don't make the mistake of damaging the lines trying to get the rubber off. pulling at an angle can deform the roundness, and a sharp razor can damage the pipe if not done carefully. I don't have a problem cutting the rubber if I need to, I just do it in gentle passes and try to pry the cut rubber with a screwdriver.
If you're reading this too late, here's a method to restore a mashed pipe. cut a section of metal pipe ID=5/8", and weld and arc length less than 1/2 the circumference to a set of vice grips. weld a smaller metal dowel to the other jaw, then slowly message the soft pipe till it's in the correct shape. If you choose to heat it, stick with a low heat to not damage the copper.

20191022_134010.jpg
 
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Congratulations! Your heater box is now out. to get the core out of the box, you have to undo some of the linkage on the box. Before doing this, I took a video of the linkages moving so I know how to put it together. I got away with only undoing one screw (I believe the one closest to the bottom when you first open the video. Then undo the following:
20191012_150130.jpg

whatever screws in these pictures are still tightened down don't have to be removed. I let them be so as to keep the original orientation of the pipes.
20191012_150211.jpg


This last screw (and everything else in this pic) goes between the upper and lower halves of the box
20191012_152113.jpg

Even with all these out, the core was still hesitant to come out. I had to walk it back and forth, it eventually came out scraping the foam off against the plastic box. Just don't be too rough with it.
I had expected a leak coming from where the copper pipe sections meet the pipes coming off the box. This doesn't appear to be the case. Like others on mud have done, these will be soldered together to make one piece. It won't make it any harder to remove/install in the future, it just eliminates one more leak point. My guess is they did this so that the same heater core could be used in multiple applications. @beno, if that's the case, could we look for these cores on other vehicles besides 60 series?
20191012_152700.jpg


20191012_152714.jpg
 
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Joined
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I took on this project with the hope of being able to youtube educate myself and repair the core. I started with a crude pressure test. Conveniently, my bike got a flat the same day...
20191014_192105.jpg

Here's's a link to a video of my pressure test. I got special permission from my wife to use a kitchen tool for a car project this time, but only under her close supervision. (PS, don't use her plastic teaspoon to remove brake fluid from the reservoir :doh:)
Turns out there's 3 layers of tubes in these heaters, and it looked like the leak was coming from the middle one. That's beyond my paygrade. Fortunately, my neighbor's father in law is a cruiserhead and let me know of a good local place I could take my core to. This brings us to last week. The shop thought they could do the job the same day I gave it to them. Clearly they underestimated the job cause it's still not ready, but supposedly they're now just doing some final tests. time will tell.

Once I start putting things together, I want to re-foam the ducts. I know this is the usual protocol, but does anybody have recommendations for a good foam replacement? The shop said they just get adhesive foam strips from lowes or home depot. If nobody chimes in I'll go that route and report back...

Also...anybody have more advice on what components need to be replaced when going R134a? How do you know if you need a new expansion valve?
 
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Adelaide, South Australia
"while I'm in there", I'm thinking of converting my A/C (which has been inop for 10+ years) to R134a. I don't know much about why it doesn't work other than when I jump the compressor clutch the air temp hardly changes. I don't want to try to source R12 only to find I can't hold it.
Consider recharging with propane rather than R134a.. mine's been running propane (well, a commercially available product called Hychill in Australia which is mostly just propane) for about a year now. No issues and a simple recharge with no system changes.
 
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