[Mihogan]

Hi guys. AC Compressor isnt engaging, so I think I need to add freon to the system (r134a, right?)

Anyway, just want to get an idea of what I'm doing before I actually go and do this. Where do I add the freon? How much will I need? Do I do this with the engine on? AC on? When do I stop? Thanks!

[Finallyajeep]

Im curious about this too.

[ExpressoNate]

Oh god, untrained auto HVAC here we go...

You need an epa 609 registration in some states.

You need to know factory specs of the system (R134a amounts and oil amounts)

Replace the dryer (about $20)
New o-rings wherever you can find them (they are the cause of 99% of your leaks) Before installing them, dip them in HVAC oil, and ensure the mounting location is clean!
Get a PROPER hvac gauge set (high side and low side pressures. The can with a gauge is junk and only reads low side in a ballpark guesstimate)

Attempt to pull a vacuum in the system. If you cannot, continue hunting for o rings. Listen to the lines and components. If you cant pull a vacuum, and run out of ideas, get r134a with leak detector and stopper, and follow their directions (may seal o-ring leaks, but unlikely. Useful under UV light to trace leaks)

The HVAC hoses have standard sizes for high, and standerd sizes for low. You cannot connect them incorrectly, but still hold the can with the bottom facing away from you.

Not a bad video

YouTube

YouTube

Good luck
~Nate

[AZ Jeff]

I will add to "ExpressoNate's" comments: unlike the old R12 systems, there is a VERY FINE LINE between enough refrigerant and TOO MUCH refrigerant in an R134a system. Owing to this, you cannot just "throw some in" and measure pressures.

You MUST evacuate the system of all existing refrigerant and refill BY WEIGHT to the correct amount.

Every year, we get one or more guys on this forum who buy those cheap R134a can tap/gauge kits and try to add their own refrigerant. Every year, we get somebody who hydrolocks his compressor and trashes it, because he did not know you can EASILY overcharge an R134a system.

To the OP---based on your questions, I assume you have very little experience working on AC systems. If that is the case, I STRONGLY urge you to have a professional diagnose where your leak(s) are. Then you can fix those yourself, and then pay the same pro to evacuate/refill the system. It's the most cost-effective way to get good working AC.

[jeepkid03]

Originally Posted by AZ Jeff

I will add to "ExpressoNate's" comments: unlike the old R12 systems, there is a VERY FINE LINE between enough refrigerant and TOO MUCH refrigerant in an R134a system. Owing to this, you cannot just "throw some in" and measure pressures.

You MUST evacuate the system of all existing refrigerant and refill BY WEIGHT to the correct amount.

Every year, we get one or more guys on this forum who buy those cheap R134a can tap/gauge kits and try to add their own refrigerant. Every year, we get somebody who hydrolocks his compressor and trashes it, because he did not know you can EASILY overcharge an R134a system.

To the OP---based on your questions, I assume you have very little experience working on AC systems. If that is the case, I STRONGLY urge you to have a professional diagnose where your leak(s) are. Then you can fix those yourself, and then pay the same pro to evacuate/refill the system. It's the most cost-effective way to get good working AC.

x2. Definitely have a pro do your A/C. If you trash the compressor then it will be MUCH more expensive.

[Finallyajeep]

Ok this is one thing ill be leaving it to the professionals lol

[NW99XJ]

i say who needs a/c? JUST TAKE YOUR DOORS OFF!!!

[Azzy]

Lat time I tried taking a vehicle to get an AC diagnosis, the shop (and dealer) both said that I would not only have to replace the compressor, but the entire system, plus evac and recharge.

So sometimes, taking it to a shop is going to run you in the $800+ range.... just saying.

[NW99XJ]

I've actually heard that's a common response. Apparently nobody likes to spend the time and effort required to track down the issues with the XJ A/C systems. Its easier to replace the whole thing than be liable for the reliability of the repairs, plus they make more money doing the swap.

[AZ Jeff]

Originally Posted by NW99XJ

i say who needs a/c? JUST TAKE YOUR DOORS OFF!!!

I invite you to come to Phoenix in July in the monsoon season and tell me how that works for you.

[cumminsjeep24]

Those recharge cans are garbage. If you are in fact low on refrigerant, you have a leak somewhere and it will keep leaking. Also, you dont know how low it really is and you dont want to overcharge it. If your compressor isnt turning on, it could be the high pressure switch or the compressor itself. I would go to a shop and have them take a look at it. the HVAC system is not something you want to try and do at home if you know nothing about it

[Mywrangler94]

I go through this every spring and summer. I must have fixed a thousand systems....Listen to Nate, and the first person that tells you..."you have to replace the whole system"..say thank you...and run. If they don't want the responsibility, or take the time to track down the problem then they shouldn't be in the business. At my shop, we evacuate it, if it will, fill it, dye it, and tell the customer to come back in 3 days, or if it stops working before that. Thats 99 bucks. Once we find the problem, tell the customer how much to repair, and fill it for nothing if we do the repair. So, take it as you will. But thats just me....good luck...

[djb383]

We replaced everything a/c under the hood except the condenser (in the driveway), flushed evap & cond, added proper amount of oil and had shop pull vacuum and add freon.....34F at the center vents now.

The more the kiddo and I dig into the XJ, the more we realize its simplicity.

[Mihogan]

Ok... thanks for the advice guys. But, to be honest, this has been killing me and I'd like to at least know where it was just to see if I was right: where is the low-pressure feed to the AC compressor?

[djb383]

The green cap to the left.