Hey Team.

So my AC wasn't cold and about a 7 weeks ago I put a can of 134 in and got the pressure to 35 (on an ez chill guage). Everything was working fine, super cold air etc.
Now, about 7 weeks on, the compressor makes a single click when I turn the AC on and there is a hissing noise once I turn the engine off after using the AC. With the hood up, it sounds like It is coming from the passenger side close to the manifold, but not 100%.
Also, the AC pressure has also dropped to 25.

I have put my hands in the area of the AC lines and where I think the hiss is coming from (after turning the engine off), but can't feel any air coming out anywhere. There is no oil or liquid in the area either.
The AC is still super cold and works fine.

Any ideas?

Cheers!

 

What year is your XJ? Any fuel work done lately (pump, filter, etc?)

 

Sorry mate, forgot to add that - 1999.

Nah, no work done.

I also just checked the heat and it isn't working. Drove it round the block to let the temp get up, but still not hot air.

Cheers!

 

Is it a Right hand drive Jeep? I'm just curious because you've used the terms "mate" and "cheers" and mention the "manifold" on the passenger side.

Re: the lack of heat. I'm assuming that the FAN works correctly, the vents direct the air correctly, but the air is ambient temp when it's set to hot. Did a previous owner bypass the heater core?

 

That is great, well spotted. I am a Kiwi, but now based in the US... So the old girl is a lefty.

The vents work and direct to the requested spots - feet, face etc. It wasn't working when I purchased it, as one of the vacuum lines was off, so reconnected and it works great.
Yeah, the air is outside temp at best now. I don't know for sure if the old owner did that, but I highly doubt it... reason being, the simplest issues were never fixed, instead he said "I didn't get that fixed, as it was going to cost me"
And since owning it, I have fixed 8 different issues for under $200 (sway bar, AC, trunk. electric windows, vacuum hose, park break...etc)

Cheers!

 

Hissing is normal after you turn the AC off, it's the high and low side pressures equalizing.

 

If you've added refrigerant previously without repairing a leak, then you still have a leak. Take liquid dish soap and put it in a spray bottle. Add just enough water to make it spray. Turn the engine off and spray all exposed parts of the ac system and look for bubbles.

 

Also invest in a full gauge set. You're only seeing 1/2 the story by checking the low side. The Harbor Freight set is fine for home use and is not too expensive.

https://www.harborfreight.com/ac-r13...set-62707.html

Don't be tempted by sealers, they can really make a mess of things. Find the leak and fix it. If not under the hood then the evaporator is the most likely culprit.

 

I concur with the others: The hissing is equalizing the high and low pressure sides, and you still have a leak. It's not really that fast though. Spray around with soapy water as advised, but many leaks on older compressors occur at the front pump seal, which eventually DO leak ...or maybe the rear gasket. Or could be an o-ring too. If you see a connector that's oily, that's probably where the leak is.

For guys who are highly mechanically inclined, have the tools, and want a challenge, a guy can replace that front pump seal and not buy a new compressor. Should be able to do it on the car if the compressor is up on top. Basically pull off the clutch and you can get at the seal. Buy the parts from the outfit below (they're great). I've done it a couple times, once on a Jeep.

Compressors can actually last a long time. Mine had a ton of miles on it and I thought it would be worn inside. I disassembled the whole compressor to inspect ...the pistons and parts looked brand new inside ...just needed a new front seal. I mainly disassembled it because at the time I'd never torn apart and rebuilt an A/C compressor. And also, I'd had some new replacement A/C compressors at the time, that died in less than a year. OEM quality man ..hard to beat! If you go to do that job, I'd replace the clutch bearing too. Not a bad job and a lot cheaper than replacing the whole compressor and re-doing refrigerant, especially on vehicles with expensive compressors. But if you're not up on all the repairing stuff, just take it to an AC shop and have them deal with it.

https://centuryautoair.blogspot.com/...-sanden-5.html

https://www.shopcenturyautoair.com/s..._Products.html
(parts)

 

Thats great news, thanks!

 

The previous owner said it hadn’t been working for 2yrs and he didn’t want to pay the shop to fix it.
I’ve been running on an 18oz can for 8 weeks now and it’s still super cold.

I’ll give the spray a go, cheers!

 

I’ll give the soapy water a go and see what I find.
As for the evap, I think I’ll buy another can of Freon to get through summer and look at it closer to winter.

I’ve gone 8 weeks on one can, so at most 2 more will see me right.

after summer, I’ll need to sort the heat out.... ha

Cheers

 

I’ll try the spray and see how I go. The compressor was replaced 10 months ago, so should be fine.

My main worry was the hiss, as I’d never noticed it before. And also the single click from the compressor when I turned the AC on.

Cheers!

 

Sorry to bring this topic back up, but still working on the old girl.

I check the refrigerant pressure every few weeks and it hasn’t moved, so maybe I just never filled it enough. I was told the tank is 22+ oz and I only put in 18oz (excluding the off spray)

So the AC is still running nice and cold, but I have a click.
when I first turn the AC on there is a single click from the compressor, then again after maybe 20-30mins.

is this normal or maybe because the Freon is low?

Cheers team!

 

In normal AC mode the AC compressor cycles on and off as needed so you will hear clicks as the compressor cycles.