Air Conditioning an 87 Grand Wagoneer

[mantonas]

I searched the forums for previous threads concerning air conditioning and I didn't find anything so I'm posting this.

I want to get the A/C working on my 87 Grand Wagoneer. I checked Rockauto and all the parts are available except the hoses. That's ok; I can get custom hoses made locally. I'm just a little stumped by a few things and I wanted to get some guidance from experienced folks before I drop 500 bucks and rip everything apart.

My first question has to do with the evaporator core and the expansion valve. I have an old A/C box that I bought on Facebook Marketplace that came out of an 86, which I assume is the same as my 87. When I took it apart, I noticed that the evaporator has three connections.

On the inlet side of the evaporator, the expansion valve connects there, and the line containing cold high-pressure liquid refrigerant from the condensor connects to the expansion valve.

On the outlet side of the evaporator, the line returning hot low-pressure gas from the evaporator to the compressor connects there. However, in the side of the tube leading to this connection, there is another connection that accepts a small sensing tube from the expansion valve. So the expansion valve is sensing the pressure or the temperature near the outlet of the evaporator and using that information to adjust how much the valve is open.

The expansion valves sold on Rockauto match this configuration: they include the sensing tube that connects to the side of the outlet tube from the evaporator.

However, none of the evaporator cores sold by Rockauto look like they have the connection point in the side of the outlet tube for the expansion valve sensing tube. What do you do with that? Is it possible the pictures are inaccurate? They sell four makes of evaporators and 3 out of 4 lack this connection (the 4th had no picture) . Has anyone ever replaced their evaporator and run into this problem?

Second, how the heck do Grand Wagoneers regulate A/C temperature in the cabin in response to adjusting the sliding temperature switch on the A/C control panel? The heater core is nowhere near the evaporator core so that's not how. I know there's a thermistor in the evaporator, so is temperature controlled by clutch cycling?

Any help would be greatly appreciated.

Thanks!

[SJTD]

The evaporator they're selling may be for the XJ.

There's a thread here from a while back where the poster had trouble with a new spansion valve. Turns out there was a plug in it that needed to be removed.

As far as I know you're correct about cycling the pump for temp control.

Should be able to find some threads here on AC there are others in addition to the one I mentioned.

[babywag]

Be very wary of AC parts being correct.
Many many computer systems have XJ parts vs. SJ parts.
I ordered/received several that were incorrect and had to be returned.

I had my evaporator flushed, leak checked, and reused it.
Finding a correct replacement was beyond ridiculous.

Finding a correct condenser was also extremely difficult.

This was many years ago but some folks have had same experiences recently.

['89_Wagon]

On an 89 there's a temp sensor probe that sits on the evap core. That sensor sends a signal to a module that cycles the clutch on the compressor. The probe is a thermistor I believe and I think I have a post with the resistance values. I bought a 4seasons evap and it had that port you need for the valve. Just make sure to take out the plug. Maybe you year is similar.

[mantonas]

I would really like to see that post with the resistance values for the thermistor! I think mine (a 1987) has one too based on research I've done. The 86 underdash A/C box I took apart also had one, so I guess I have a spare, but who knows if it works. I would like to know that I could replace it with a generic one if I had to.

Also, I would really like to know the part number for the 4 Seasons evaporator you bought that had the pressure sensing port for the expansion valve!

Thanks in advance.

[jeepman42]

Agree with Babywag; you have 2 evaporators, one should be good?? Use what you have. until proven otherwise.
Suggest you first tackle a closed system. Hook every thing up, pump down for 30min. w compressor valves open. Charge w one can Freon or 134 & leak test w electronic tester. (propane type has open flame& releases phosgene w Freon)
IMHO compressor seal or loose connection main culprits.
Then tackle other issues.
{{ If you change hoses, the line from site glass to dryer has a restriction valve in the hose. New hose did not work as it did not have valve, so I had to use old hose. }}

Free opinions may only be worth what you pay for them?

['89_Wagon]

Here's a link to the evap I bought from summit. The 3 connections are visible.https://www.summitracing.com/parts/FSS-54613

The probe shuts the compressor off to avoid icing on the core. Cabin temp is regulated by allowing fresh air in through other vents. The AC only draws air in from the cabin and is completely separate from the heater system. So kinda an off/on sorta of thing.

I replaced the entire system and was able to find the parts I needed new. I used a crimping tool to make the lines. Not difficult.

I'll get those values out of the manual for you.

[mantonas]

Thanks all!

I have to say something in response to the comments that I should just use the evaporator that's in there or the spare I just bought. I don't disagree that I could get away with doing that and it might be a waste of money to replace a perfectly fine evaporator. I guess the reason I want to replace it boils down to just one issue: the hoses. The Grand Wagoneer followed the AMC design of connecting the hoses to the evaporator and running the hoses through the firewall. On all the other cars I've had, the hoses were completely removable within the engine bay. Maybe AMC did this because it made the cars easier to put together on the assembly line, who knows. Anyway, if I'm going to upgrade the A/C, I want to replace the hoses. If I could remove them without having to drop the A/C box, I would definitely leave the evaporator alone and try to make the A/C work without disturbing it. I would only replace it if it was clogged or leaking. But on the Grand Wagoneer, if I replace the hoses, I've got to remove the A/C box, unwrap the mastic tape, and almost remove the evaporator from the box. I'll be damned if I do all that work and NOT put a brand new evaporator in there. Plus, if it's a money thing, I kind of don't care. This is a project car which I'm restoring as a hobby. Plenty of people drop a whole lot more coin on their project cars to do pretty frivolous stuff than I would be spending on this evaporator. So I'm not saying I'm right and others are wrong, I'm just explaining why I want to go this route.

[rocklaurence]

I did a video on the rebuild of the Ugly Truck AC. This will help

https://www.youtube.com/watch?v=rnGx15pGL7U

[babywag]

just be warned aftermarket parts are NOT what they used to be.
Most are of poor quality some are so bad they require modifications just to be installed.
I bought all new parts thinking new is better. I was WRONG. New isn't always better because even if they work initially they may fail in short order.
It's a roll of the dice these days!!

I redid mine used evaporator was only original part.
2 expansion valves due to above.
2 AC compressors due to above.

Your mileage may vary.

Also 2016 redid entire AC in my caprice. New everything.
Compressor failed immediately (bad clutch)
Condenser just failed few weeks ago...sigh

[mantonas]

This is a good perspective. I don't doubt your experiences and I agree with what you say. Some new parts are crap.

I found this outfit online and I have talked to them twice:

http://autoacsolutions.com/products/underhood-packages/a-c-under-the-hood-upgrade-package-r12-to-r134a/

They sell a complete underhood kit (does not include evaporator). It is supposed to be total drop-in, no modifications required. All parts are U.S. made. Hoses are crimped on one end and have extra length; the other end needs to be crimped locally after fitting everything up and measuring hose lengths.

Price including shipping is $795 dollars and it arrives in less than a week. It's pricier than just buying all the parts from Rockauto that they say will fit; I compared prices and if you buy everything that you can get from Rockauto, plus a Sanden compressor mounting bracket, hoses, fittings, etc., there's a couple of hundred dollar difference. It's a bit of a scavenger hunt finding all the parts; the thought of getting a complete kit where all that work is done for you is very enticing. Plus, these guys really seem to know what they're talking about. They apparently have 40 years of experience doing this.

I am very tempted to do this. However, if I can just be wishy-washy and put off making any decisions for two more months, I will have nine months or so where I don't need A/C and I can save up money.

[babywag]

rockauto is no bargain imho.
saving a few $$ got me a huge hassle on wife's car!!
had lots of bad crap from them over years.
fine if able to wait around with nonop car until their replacement junk arrives.

[mantonas]

I had another idea yesterday: take advantage of the service valves that are attached to the factory York compressor and just replace the compressor without breaking open the system. I can get a new York compressor for a little under 200 bucks. I can replace it, then evacuate the system, vacuum it down, and refill it with a few cans of r134. I would gladly pay 200 bucks to have A/C for the next few months. Normal people take their cars to the A/C shop all the time and spend way more than that to get their A/C fixed.

Even if I redo it in a year or two it might be worth it.

[SJTD]

But you can't use 134 with the mineral oil that was used with R12. Need to have the system flushed.

Could use one of the flammable R12 replacements if you can't find or don't want to pay for R12.

Should prefill the pump with the correct amount of oil. A dipstick is used to check it. That's another thing the service valves are used for. You can vent just the pump and check the oil level.

[mantonas]

I don't think I mentioned this yet, but the fittings in the system on my car have been changed to the R134 type by a previous owner, so I assumed it had been converted to R134 already. May be a bad assumption.

Every day I have a new plan. Yesterday I was looking at the compressor and visualizing it with a Sanden instead of the York, and I realized that the upper radiator hose would likely interfere with the A/C hose connections to the compressor. I would like to hear from someone who has done the swap as to how they handled this.