98 A/C resurrection

[SurplusFan98]

Recently rescued a 98 2wd 4.0 5speed XJ. I've been steadily working through issues and making progress. My next big hurdle is fixing the A/C system. I don't have any experience servicing vehicle A/C systems, but I'm determined to learn. Been going to Youtube academy to figure it out, but with you guys being experts and all, I thought I'd include you in the process. Here's what I've done so far:

1. In the cab with the A/C and fan on full blast, I get plenty of air, and the vent positions change as they should, etc. Should be all good inside.
2. Under the hood with the engine running and A/C on, I hooked up some manifold gauges and got readings. About 4PSI on the low side, and looks like roughly the same on the high side. Figured I was just basically out of refrigerant.
3. Noticed that the compressor wasn't engaging, which I know could be the low pressure switch. I made a jumper to bypass the switch just to see if it would come on. The electric fan comes on like it should, but the compressor clutch doesn't engage at all. Pulley spins freely, but it doesn't grab. I checked that its hooked up, but I haven't probed it for voltage yet.

So am I correct that compressor should be engaging when the switch is jumpered even if there's basically nothing in the system? What's my next step here? Is it get electrical readings going to the compressor? What am I looking for?

 

[Rob Mayercik]

I'd either jump power directly to the compressor clutch or put an ohm-meter across it - if direct power to the clutch (don't need the engine running) doesn't cause it to activate and pull into the pulley or the ohm-meter reads as an open-circuit, the clutch itself probably needs to be replaced.

 

[tech1001]

Also check to see if the clutch plate gap is not to large you can check it with the engine off , just use a jumper wire on the hot side and then push the clutch plate in and see if it will engage .

 

[SurplusFan98]

Thank you guys!

I tried both of these suggestions. I can get the clutch to engage occasionally via direct battery power. I even got it to engage once through the low pressure switch for just a moment. A few times I had to give it a little push with a screwdriver.

Even when the clutch doesn't engage, I can see it move a little like it wants to but it doesn't grab. That seems to indicate that my gap is too large. Either way I'm going to have to pull it out. Should I just clean it up really well and put it back as it is to test, or does it hurt anything to go ahead and remove a single spacer?

 

[RCP Phx]

The factory spec is .016-.031", so removeany combination of shims to achieve that gap.

 

[SurplusFan98]

Thanks to all who have replied so far. I now have my clutch engaging predictably. I took the clutch apart, wire wheeled it (gently) and buffed with a scour pad, and cleaned well with brake clean. I removed 1 spacer washer (of 2). Put it all back together, and it appears to be doing what its supposed to do.

I did put a voltmeter on my connection. I'm only getting 11v at the connection, but again its all working. I'm not going to go borrow trouble right now.

So the next steps... I'm going to go borrow a vacuum pump and see if it'll hold vacuum. After that it gets a little unclear.

• I know how much refrigerant to add, but what about oil, or dye (should I even bother with dye if it holds a vacuum)? How do I know if I need to add oil, and how do I know how much?
• Do I need to try to recover any refrigerant? There doesn't seem to be much of anything in the system (I would think 4 psi in a closed system isn't that abnormal when the heat index outside is like 108).
• If the system is empty, do I still fill it to the listed weight of refrigerant regardless of the outside temp, or should I do it based on outside temp and pressure?

 

[RCP Phx]

Holding a vacumm is not a guarantee it will hold pressure so dye is a good idea until you can confirm it will hold a charge. Most of the oil "should" remain in the compressor but.......

 

[Badvudoo]

Pull a deep vacuum on the system (run the vacuum pump for at least an hour) let it rest under vacuum for another hour. If the gauges haven't moved the system should be tight. Have you done a visual of the hoses, condenser and filter/dryer ? If they are without an oily film you should be ok and no oil leaked out. At this point adding a table spoon of dye is a good idea follow that with the listed amount of freon.

 

[SurplusFan98]

Thanks for the suggestions.

I borrowed as small vacuum pump from Oreilly's. got everything hooked up and ran the vacuum for about 5 minutes. Got it down to about 26inHg and figured that was probably the best that my borrowed pump would do. Closed up my manifold valves and let it sit for an hour. Now I'm at about 21inHg. That seems to indicate a very small leak.

I'm going to repeat this to double check. If I do have a small leak, how would you guys proceed? I agree a small amount of dye needs to go in. I have seen that you can buy refrigerant with some seal conditioner in it that makes the seals swell and seal up tight. Maybe that would be enough to treat the leak. Opinions?

 

[RCP Phx]

I wouldn't waste my time with any "conditioner", you can buy a master seal kit for cheap!

 

[jhenke]

I would replace all the o rings and retest.

 

[RCP Phx]

They are all about the same..... https://www.amazon.com/Performance-Tool-W5201-Ring-Assortment/dp/B0002KO1XK/ref=asc_df_B0002KO1XK/?tag=hyprod-20&linkCode=df0&hvadid=312158556601&hvpos=&hvnetw=g&hvrand=3365557030005669557&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9029983&hvtargid=pla-429142200198&th=1

 

[acruz95]

Also check for faulty Schrader valve which are easier to replace than o-rings.

Sent from my SM-G991U using Tapatalk

 

[Bzamora]

You guys are lucky. My A/C isn't working either, and I discovered that here in the Peoples Democratic Republic of Washington we are no longer allowed to buy refrigerant without a commercial license. So much for fixing it on my own.

 

[sjx40250]

Do a search on Propane as a refrigerant. It was the initial refrigerant before there was R12 or R134a. The only issue is its flamability.

 

[XJlimitedx99]

You guys are lucky. My A/C isn't working either, and I discovered that here in the Peoples Democratic Republic of Washington we are no longer allowed to buy refrigerant without a commercial license. So much for fixing it on my own.

Its probably easiest to have a shop do the reclaim/filling process anyway. You can still get manifold gauges and a vacuum pump to confirm the system is in good shape before having it filled.

Thanks for the suggestions.

I borrowed as small vacuum pump from Oreilly's. got everything hooked up and ran the vacuum for about 5 minutes. Got it down to about 26inHg and figured that was probably the best that my borrowed pump would do. Closed up my manifold valves and let it sit for an hour. Now I'm at about 21inHg. That seems to indicate a very small leak.

I'm going to repeat this to double check. If I do have a small leak, how would you guys proceed? I agree a small amount of dye needs to go in. I have seen that you can buy refrigerant with some seal conditioner in it that makes the seals swell and seal up tight. Maybe that would be enough to treat the leak. Opinions?

I also have been getting into my AC system recently. First time ever learning to work on AC. From what I've been seeing, dropping 26 to 21 inHg in an hour is still a decent leak. Mine dropped 30 to 29 inHg in an hour, then to 26 inHg overnight, and held there over a weekend. I haven't made more progress on repairing yet, but I am still of the mindset that my system has a leak.

I had a considerable amount of trouble getting the pump/gauges to work properly. I've never used them before, so figured it was a learning curve, but it wasn't nearly as simple as "hook them up and suck the system down."

The biggest problem I had was finding the o-rings in my rented manifold gauge set were all pretty toast. I discovered this after having a hard time pulling the system down to vacuum, and eventually trying to eliminate variables by pulling vacuum on just the manifold and hoses (with the valves closed at the Jeep's Schrader valves). After seeing the system lose vacuum with that part isolated, I pulled some o-rings out and found them to be damaged/worn. I ordered this Yellow Jacket 19020 Refrigerant Hose Gasket set. They weren't exactly the same as what I was replacing, but they worked.

However, that wasn't the only issue I had with the pump/manifold. The other problem I had was the o-rings collapsing and getting sucked into the hose, which would block the flow from the pump. This took me a bit to figure out, but ultimately I found it by hearing a change in sound when the pump was struggling vs not struggling, and correlating that sound to tightening/loosening the fitting at the pump. I found if I tightened the fitting too much, the o-ring would collapse, but if I didn't tighten it enough, it would leak. Again, replacing the o-rings solved this problem.

Not sure how all of that relates to you, but it made me less confident in my readings from the gauges.

While your system is empty, you should definitely replace the accumulate/drier. There is a desiccant in there that should not be left exposed to air and is cheap/easy to replace.

My next step from here, and probably what I imagine yours to be as well, is replace all the o-rings on the system. Either that, or have the system recharged with dye and wait for it to leak again, hoping to find the leak via dye. Could also recharge the system and search for a leak via a sniffer. That would be the best route.