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Need help charging A/C

freedom_in_4low

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I don't like the TJ FSM's pressure chart because apparently whoever wrote that chart thinks Jeeps can violate the laws of physics - R134a is R134a and the high-side pressures the FSM wants to see are way above any other reference I've ever seen. I suppose they're covering a 10 degree step instead of five, but it still trends high. Every other FSM I've seen is in line with this chart:

View attachment 338127

With that said if you're at 85 degrees ambient then I'd follow the flowchart on the next page of the FSM starting with "normal pressures but temperatures too high". Oil overfill seems unlikely unless you've used one of those combination cans with oil and R134a in it, so I'd double check the blend door control and possibly the door itself to make sure it's not mixing heated air.

After you verify that then I'd plan on getting the system evacuated, and open it up to see what's in there.

I agree. Having engineered R-134a systems for two different HVAC manufacturers (but no automotive), I've never purposely designed anything to run past 270psig on its worst day and actually use a 350psig relief valve, which requires a high pressure safety cutout no higher than 315.

It irritates me because running a lower high side pressure would really help out the engine cooling system on those 100+ days, but I guess automotive does things as inexpensively as possible since no one is judging them on their SEER.
 

freedom_in_4low

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This is what I was going off.

View attachment 338125

I hate that chart for taking no account whatsoever of humidity. The system is going to react completely differently to an 80 degree ambient in Florida vs the same in Utah. If it's humid, you'll have a warmer temp coming out and higher pressures at both ends because the system is having to put more work into the latent heat load of condensing the water vapor in the air.
 
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UglyDuck

UglyDuck

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I hate that chart for taking no account whatsoever of humidity. The system is going to react completely differently to an 80 degree ambient in Florida vs the same in Utah. If it's humid, you'll have a warmer temp coming out and higher pressures at both ends because the system is having to put more work into the latent heat load of condensing the water vapor in the air.

That’s true but we’re talking Arizona with maaaybe 15% humidity, and vent temps of 80. Somethings wrong here-aside from the chart.
 
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UglyDuck

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If a hose blew you might of lost some oil and a lack of oil. Am kinda shooting in the dark here. Did you add any oil when you replace the hose?

I’m sure I lost a little, hard to quantify though. Hose didn’t “blow” per se but did fail. I added some oil, again I’m blind though because there’s no way to know where I’m at now.
 

MikekiM

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I need to fix my AC too.

Read everything in this thread and have zero idea what you all are talking about.

When I bought the TJ PO had installed a HVAC control unit that had no AC option. I replaced that with a new unit. AC blows hot.
I used the commercially available recharge canisters and it took all of a single blast for the built-in gauge to show full. AC still blows hot. I can hear the compressor clicking on and off.

I think I'll bring it to my corner mechanic and let him do it.
 

NashvilleTJ

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I need to fix my AC too.

Read everything in this thread and have zero idea what you all are talking about.

When I bought the TJ PO had installed a HVAC control unit that had no AC option. I replaced that with a new unit. AC blows hot.
I used the commercially available recharge canisters and it took all of a single blast for the built-in gauge to show full. AC still blows hot. I can hear the compressor clicking on and off.

I think I'll bring it to my corner mechanic and let him do it.

The "commercially available recharge canisters" are a band aid at best, and in the situation you describe would not make any difference. It takes special equipment to properly charge an A/C system. The system has to be leak tested and vacuum purged prior to charging. In your case there is likely a leak somewhere, or a bad component - otherwise the PO may not have swapped the controls, but who knows.

In general, any A/C unit low on pressure has a leak somewhere, which has to be found and corrected. Unless you have an A/C vacuum pump, manifold gauges, leak detection equipment (none of which are inexpensive), and the knowledge to use the equipment, you are better off having a professional take a look.

Another piece of advice - I've seen you ask this question in at least one other thread. You are more likely to get help if you start your own thread and ask the question.

Good luck.
 
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Terry from Texas

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I’m sure I lost a little, hard to quantify though. Hose didn’t “blow” per se but did fail. I added some oil, again I’m blind though because there’s no way to know where I’m at now.

I would have it professionally evacuated and recharged. The equipment at my dealership is much better than the equipment I have at my disposal at home. You might just fix the problem with a proper evac and recharge.
 

tr21triton

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Blue Ridge' Ga
The "commercially available recharge canisters" are a band aid at best, and in the situation you describe would not make any difference. It takes special equipment to properly charge an A/C system. The system has to be leak tested and vacuum purged prior to charging. In your case there is likely a leak somewhere, or a bad component - otherwise the PO may not have swapped the controls, but who knows.

In general, any A/C unit low on pressure has a leak somewhere, which has to be found and corrected. Unless you have an A/C vacuum pump, manifold gauges, leak detection equipment (none of which are inexpensive), and the knowledge to use the equipment, you are better off having a professional take a look.

Another piece of advice - I've seen you ask this question in at least one other thread. You are more likely to get help if you start your own thread and ask the question.

Good luck.

the vacuum pump can be borrowed from any autozone or oreilys . i think the guages can be also, but I bought my own set. many times a leak can just be a o-ring and they can be purchased at the same place and are easy to replace.
 

MikekiM

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East of Montauk, NY
The "commercially available recharge canisters" are a band aid at best, and in the situation you describe would not make any difference. It takes special equipment to properly charge an A/C system. The system has to be leak tested and vacuum purged prior to charging. In your case there is likely a leak somewhere, or a bad component - otherwise the PO may not have swapped the controls, but who knows.

In general, any A/C unit low on pressure has a leak somewhere, which has to be found and corrected. Unless you have an A/C vacuum pump, manifold gauges, leak detection equipment (none of which are inexpensive), and the knowledge to use the equipment, you are better off having a professional take a look.

Another piece of advice - I've seen you ask this question in at least one other thread. You are more likely to get help if you start your own thread and ask the question.

Good luck.

I have none of that equipment.

Yes, I've made mention to it in various context, but truth told I am not that motivated to fix it at the moment so haven't started a dedicated thread. Appreciate your thoughts though.
 

IOwnCalculus

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Oct 31, 2019
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I’m sure I lost a little, hard to quantify though. Hose didn’t “blow” per se but did fail. I added some oil, again I’m blind though because there’s no way to know where I’m at now.

That's an annoying thing about air conditioning - the oil is distributed throughout the whole system so the only way to know how much oil is in it, is to take it apart and dump all the oil you can out of everything. Might be able to get most of it out of the coils by blowing it out with compressed air. But of course having a system open that long might also require a new drier anyway.

In general, any A/C unit low on pressure has a leak somewhere, which has to be found and corrected. Unless you have an A/C vacuum pump, manifold gauges, leak detection equipment (none of which are inexpensive), and the knowledge to use the equipment, you are better off having a professional take a look.

Leak detectors are surprisingly inexpensive these days, I picked one up off of Amazon for $23 a year ago and it seems to still be tracking around that price today. It certainly won't hold up to commercial use but it's sensitive enough to trigger off of just the whiff of R134a seeping out under the caps on the service ports.
 
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UglyDuck

UglyDuck

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I would have it professionally evacuated and recharged. The equipment at my dealership is much better than the equipment I have at my disposal at home. You might just fix the problem with a proper evac and recharge.

I’ve been weighing the idea. It’s hard to wrap my head around paying someone a high price to do something fairly simple. There isn’t much I farm out, whether the vechicle is air, land, or sea.
 
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TheBoogieman

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I’ve been weighing the idea. It’s hard to wrap my head around paying someone a high price to do something fairly simple. There isn’t much I farm out, whether the vechicle is air, land, or sea.

In your situation, I'd go that route.
 

CharlesHS

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When I bought the TJ PO had installed a HVAC control unit that had no AC option. I replaced that with a new unit. AC blows hot.
I used the commercially available recharge canisters and it took all of a single blast for the built-in gauge to show full. AC still blows hot. I can hear the compressor clicking on and off.

I think I'll bring it to my corner mechanic and let him do it.
Since the PO replaced the HVAC control unit I would make sure the hoses are connected properly, the blend door is operating properly and the actuator motors are operating properly along with verifying there are no vacuum leaks in the A/C controls.