Rambler65

Well that sucks. If the '87 XJ follows standard AMC practice there were service valves and charge ports just on the old compressor, so no other service ports in the system. Wonder if someone makes a port in a barbed "T" fitting that can be spliced into a hose?

XJThrottle

I can have hoses made with service ports in them. I work for a manufacturing company that builds ride on equipment with A/C. Our systems are all custom for us. I Just need to pull a hose off and take it to my vendor to duplicate.

Rambler65

That sounds like the ticket. What I'd probably do is have a low pressure hose made up with an appropriate service port and continue to use the high-pressure discharge port on the compressor.

PatHenry

So I checked the fuses - info I found specified slot 8 in the PDC (a 60 amp fuse) and slot 5 in the fuse block. It wasn't clear what slot is 8 in the PDC, but the 2 60amp fuses marked aux power (or something like that) were both good, as was the 30 amp fuse in slot 5.

I jumped the pressure switch and the compressor and fan kicked on. I meant to run it for more than a few seconds, but I dropped the paperclip. (The system has the full amount of refrigerant as best as I can determine.)

So is there anything other than a bad switch that I'm missing?

Could a large volume of refrigerant escape such that it's legitimately cutting off the compressor without me having noticed something awry when I was filling it? I did blip the lp service port and heard hissing before I did anything today, so there's refrigerant in the system.

I think my next step is to replace the switch. I will double check that there's a valve on the old receiver/dryer, I'm thinking it should be obvious if there is or isn't one, right?

Rambler65

It seems unlikely that you'd have a large leak if the system held vacuum overnight. A quick check would be to hook up your gauges and check that there is pressure at rest. There is no specific rest pressure but it takes something like 20 psi to close the low-pressure switch. So assuming there is sufficient pressure you can then jumper the low pressure switch and observe system pressures on your gauge set.

Yes, you should be able to see if there is a schrader valve in the old dryer. Of course that's not a guarantee that the new dryer came with one.

PatHenry

I verified the new R/D has the valve (I found a part picture online) and ordered the new switch and a new relay just to have one.

As soon as the new switch comes in I'll swap it out and see if I can finally claim victory on my A/C project!

ixanay_on-the_exjay

Perfect timing, when can I bring mine over for diagnosis?

PatHenry

Where are you at with yours?

If you want to drive out to the Westford/Groton area I'd be more than happy to help and/or let you use my tools.

ixanay_on-the_exjay

Thank you for the offer! I may take you up on that. I have not begun my journey yet and the AC was DOA when I got it and certainly been messed with (freon recharge at the very least) but this thread is chalk full of good info and I'll keep your offer in mind when I get to AC on the laundry list =]

PatHenry

Sounds like a plan.

PatHenry

So to update -

I installed the new pressure switch, condenser and lines and vacuumed the system down again. I did this in my driveway so I had left just the hood latch bar and plastic grill trim piece off, but I didn't want to put refrigerant in until I had good daylight. I finally got a chance to put the refrigerant in last night. Hooking the gauges up I get a vacuum reading of -30, so it held vacuum perfectly over 4-5 days time. I'm happy, but it held vacuum previously so I'm cautiously optimistic.

So I add the refrigerant, the compressor kicks on and I got cold air in the cabin - yeah, progress!! Last time I added refrigerant the compressor kicked on for just a brief moment and then nothing.

On a side note, my nearly 5 year old step-son was fascinated by the refrigerant can getting cold as the refrigerant was being added.

I finish adding the full 2lbs of refrigerant and shut down the engine and remove the gauges and whip out my $20 Amazon electronic leak detector and set about inspecting the lines. This sniffer beeps continuously and speeds up if it detects refrigerant. It goes off at the fitting where the low pressure line runs into the compressor. F'n hell! So I frantically set about tightening the heck out of the fitting, but it still shows a leak. This is a brand new line with a new o-ring and nylog that I took care when installing to make sure it was seated correctly. I also got a very slight leak at the other end of the line where it connects into the expansion valve block. (Fortunately, the two lines at the back of the expansion valve that connect to the evaporator (aka "the real PITA fittings") were not leaking.)

Despite the frantic attempts to tighten down the fitting, the detector still showed a leak. I step away from it and run out to pick up my daughter from my parents' and come back and when I come out to put the hood latch and trim panel back on, I take out the leak sniffer and I'm no longer getting any leak at either end of the fitting. I assumed that this meant the refrigerant had leaked out. However, when I 'bliped' the schrader valve, I got a hiss of refrigerant.

So today I take the Jeep to work and when I fired it up and put the A/C on, the compressor runs and I get "A/C cold" air (in other words, I could feel that was A/C rather than just the vent air). A little later when it was a bit warmer out I tried it again and sure enough, the compressor kicks on and I start getting cold air in the cabin.

I hesitate to declare victory just yet since it's only in the 70's around here today with very low humidity (in New England this is the type of weather that is just cool enough that we wouldn't be using A/C anyway) and I'm still disturbed by the leaking fittings right after I charged the system.
The only thing I can think is that there was too much refrigerant in the system and it pushed past the o-rings until it stabilized. However this doesn't make a lot of sense either since the factory sticker very clearly indicates 2lb of refrigerant and I had opened the system up when I replaced the lines and condenser and vacuumed it down, so there's zero chance of there being any refrigerant lurking in the system.
Also what was interesting was that the compressor kicked on and stayed running when I added the first can of refrigerant. Based on what I've read on this forum and elsewhere, I had expected that I'd need to be at least on can 2 of 3 before there was enough refrigerant in the system to satisfy the cut-off switch minimum.

00t444e

Sometimes a leak detector will still go off after you fixed the leak because there is residue left behind from where it was leaking.

Rambler65

Yes, there can still be whiffs of refrigerant floating around in the air after charging or after a leak is fixed. The electronic detectors are also sensitive to air currents. You have to back off, let the detector settle down, and verify. Sounds like that inexpensive detector works pretty well! Might pick one up myself as a backup since my Matco "Leak-Seeker" is like 20+ years old and replacement detector heads are no longer made for it.

PatHenry

It works surprisingly well for the cheapest of the cheap units. I wouldn't recommend it for anyone that is doing serious A/C work or using it frequently as it's definitely got a very cheap feel to it. Think Harbor Freight "Free with purchase" multi-meter. However it definitely did work as advertised.
For my purposes - where I'm using it for my Jeep, maybe the family car eventually and if the forum member a few posts ago takes me up on my offer to help - it's perfect.

PatHenry

Just to update - we had a brutally humid day and I was able to properly verify the A/C. A/C was nice and cold!!

So at this point I'm good with the A/C and we'll see how it holds up.