Evaporator Core/ A/C help

Hey guy's the only threads I could find related to a/c repair just answered the problem as the infamous ac problem and no real troubleshooting I'm guessing that there is a thread somewhere but I can't find it. My Taco ('95 2.7) has been in my family almost it's entire life, I recently got possession after my mom wrecked the front. The A/C holds psi (I just had to take the condenser off to replace the rad support), it had some psi on it but not nearly what it should have. The A/C hasn't worked right since around 2002 you can put a can of refrigerant and it will be cold for a few days. Now this was my cousin and then sister doing that and I bet it had something to do with never being truly swapped to 134a. I plan to pull a vacuum before attempting to recharge just to ensure all the old gunk is out. What parts do I need to swap out for 134a, I have seen some say the expansion valve is different. I also would like to know if it is possible to pull evaporator core without taking out the dash. Will be changing the blower out soon anyway its starting to rattle was thinking about swapping evap core while I was at it. Thanks for the help

 

my my my you do have a mess there

where do I start with so much gone completely wrong.

let me cover the basics, if you mix r12 with r134 or r134a it will solidify the wax in the oil like cold hamburger grease left in the pan. this will plug up and gum up everything everywhere and the system needs serious help now by a professional who knows what they are doing.

the whole system needs to be chemically flushed to remove all this wax and remaining oil from the r12 system and at this point the compressor may be a lost cause because its not worth taking it apart to clean it and reassemble it.

offhand I say you need to replace the compressor with a working one from the scrap yard and then do a flush of the lines followed by replacing the receiver drier (the long black can next to the condenser) then if there is any doubt replace the condenser coil too, you don't want to do all this only to have a leaky system needing more Freon every few months.

next by the firewall there will be some sort of metering device that regulates the pressures as it goes into the evaporator coil and that will need to be replaced, just flushing will not fix it if there is trash blocking it or causing it not to operate correctly.

now put new factory OEM o-ring seals at all the connections so they fit and seal properly and pull a vacuum with a good vacuum pump capable of reaching and holding 28 inches of vacuum for 30 minutes then refill with 134 Freon.

got all that?

now you want a better cheaper solution? hit the salvage yards and hope to find a sealed system still full of Freon and take it all, compressor, lines, condenser, evap core, and swap it all out with yours. it will save you a ton of time and money and work much better then trying to make your old system function. if you swap it out within 12 hours of disconnecting it from the other truck and keeping the ends cover by plastic bags taped tightly shut, the remaining fumes in the system will keep air from getting into the lines and keep dust and dirt out.

the last thing you do right before you are ready to vacuum in down for 30 minutes then refill it with Freon is put a new accumulator on it, this must be done no matter what solution you try.

 

Okay I figured it was going to be a huge mess, I do have some experience with A/C systems but they were all factory 134 so didn't have to worry about cross contamination. Still wondering if the evap core housing will come out without pulling the dash I don't mind scratching my arms up to save a ton of labor when working on my own stuff. I will probably order the parts new on Amazon, I have prime so free shipping on most orders.

 

I thought all new car in the USA from 1995 on had R134a from the factory. There should be a sticker somewhere under the hood saying if it's R-12 or R-134a, so double check that.

If it's still R-12 and you want to convert, then google for "R-12 Air Conditioner System Retrofit." Toyota put out a Technical Service Bulletin (TSB) for "86-94 All models with R-12 Systems." In this document, it says it's OK to leave the old mineral oil in (no need to flush the system), but you have to add oil that is compatible with the new R-134a. It also says to replace certain o-rings, but not all of them. It specifies the amount of R-134a and oil you need to add for the particular model.

Now, since this TSB only lists 1986-1994 Truck as one of the models, I'm not sure if the 95 models still had R-12, so you'll have to search for info about that or adapt the procedure in the TSB or check if the models listed have the same compressor, etc. Or maybe call a Toyota dealer to see if there is any info you can get.


As far as the evaporator core goes, read the repair manual. It looks like you only need to remove the glove box to get it out. The expansion valve is located at the evaporator core, so you can change them at the same time. I would recommend finding a way to properly torque the line fitting nuts, so you are sure everything is sealed without overtightening and breaking them. I used a set of crowfoot flare nut wrenches with my torque wrench.

 

Sweet Dr. Z thanks I was thinking it was around 98-99 when they swapped over. And good to know that I can pull the evap without the dash may swap out compressor anyway they are fairly cheap online.

 

the sticker on the back end of the compressor tells you what is uses and what was in it from the factory

if no one put r12 in it then there is no cross contamination to worry about and all you need to do is fix the leak, pull a good vacuum for half hour and recharge the system with Freon.

we can assume the leak is the condenser so replace it with a new receiver drier and make sure there are no issues with the lines and connections.

it is quite possible the wreck made the fittings loose and you just need to replace the O-rings in them and retighten everything but no matter what the last thing you should do before calling it done is replace the receiver drier. what I do is reuse the old drier just to test all leaks are fixed first, then if im confident all leaks are fixed I vacuum it down and put the new drier and recharge the system.

 

Yea I think I'm going to go ahead and replace everything but the lines anyway leak has been around at least 12 years (nobody ever wanted to spend the time or money to fix it), just first look and I can get Comp, evap core, condenser, drier, expansion valve, and blower under $250. That's mostly Four Seasons brand and Denso I have had good luck with both brands. I figure why not the system is 20 years old. Lines looked around a bill a piece.

 

My biggest fear was getting to the evap and expansion valve.

 

there really is no need in my honest opinion, any issue will just be moisture filling the receiver drier and a vacuum will remove the rest of the moisture from the system so I don't see why you feel you need to pull out the evaporator? unless you think its damaged.

99% of the time the metering device is "suspect" for not working right, it turns out to just be ice crystals blocking it due to excess moisture in the system. I really think you are overthinking things and over planning on what needs to be done.

its still good to get to know about how to work on these things though

 

You are right only cost to make sure it wasn't just a loose connection is Freon, might get lucky.

 

Here is a trick. Take the blower motor out (easy, 3 screws and it drops down), then hold a camera up where the blower was. If you get the angle right, you can snap some pictures of the evaporator core and expansion valve. Check if there is any obvious signs of freon oil leakage or corrosion. If a mouse ever got in there could be a lot of crap clogged in the evaporator fins causing odors or corrosion. If everything looks pristine, then lean toward not replacing the evaporator/expansion valve. If there's a lot of dirt you can lean toward replacing them.

 

Sounds easy enough, weather is crap here in east Texas today if it brightens up any I will yank it out and oat the pics