A/C gets weaker while driving

[annihil8ted]

Hello! I have 98 wrangler equipped with AC and for the most part it works but I noticed that over the length of a drive, it seems to be losing it's cooling ability. It goes from really cold to somewhat cold.

I thought maybe I was low on freon or maybe a leak. I hooked up one of those simple refill tanks with R123A. It showed in the green but on the low side so I gave it a quick pump. I did see the PSI raise but overtime a 5 minute span, it seemed to drop back to where it was originally and stay there. Adding small amounts of freon in would all drop more or less to the same area.

Is this indicative of a leak? Or is this more of heat saturation from the engine bay

I was also able to wiggle the lines near the low pressure fill port. Is that normal? I wasn't sure if it was designed flex or maybe one of the tubes got loose.

Something else to note too, when the clutch is disengaged and the compressor is off, I saw the PSI go up drastically on the low side.

 

[Mall'er]

...simple refill tanks with R123A.

Uhh, you mean r134a?

I would suspect if you are losing cooling as the system runs, the expansion valve or condenser is freezing up. That could be caused by a low freon issue, or a system blockage of some sorts. Leaves on the condenser, that sort of thing.

Normal for the low pressure side to increase when the compressor is off, the system will tend to equalize when not running.

 

[annihil8ted]

Uhh, you mean r134a?

Yes, sorry slip of the fingers

I would suspect if you are losing cooling as the system runs, the expansion valve or condenser is freezing up. That could be caused by a low freon issue, or a system blockage of some sorts. Leaves on the condenser, that sort of thing.

Prior to charging, the condenser would engaging on an off, similar to like breathing kinda? Haven't driven it long enough after charging to notice if it's turning on and off still.

The charge line definitely gets really cold and has moisture condensing onto it but I don't see it freezing. Condenser isn't visible right? It's in the the dash? Is the expansion valve also there too?

Normal for the low pressure side to increase when the compressor is off, the system will tend to equalize when not running.

Ah that's good to know! I was a little concerned when I saw the valve go high like that

 

[Mall'er]

The compressor should cycle as the system is running, that is normal. Rapid cycling could indicate low freon.

Ideally you would have a full gauge set to watch your pressures, the low and high should be relative.

I think the 98 still had the blower fan that sticks through the firewall? Either way, remove the blower fan, and you should be able to see the condenser to clean it. Also make sure the AC drain is clear, if not, that can cause issues also.

 

[Grenadiers]

If your Jeep has the ‘recirculating’ button, try that. Circulating interior air might help in high humidity situations.

 

[B1Toad]

Have you noticed if the air flow reduces when the cooling reduces? I had a 95 Grand Cherokee where the evaporator would begin to freeze up on long drives. Shutting the compressor off but leaving the fan on would fix it temporarily. A new low side switch on the side of the evaporator fixed it for good. Like mentioned earlier poor air flow can also lead to evaporator icing so check that as well, seen a few evaporators almost completely blocked with pet hairs.

 

[annihil8ted]

I don't feel a reduced airflow; I'm typically at 3/4 and it's not uncomfortable sitting inside at 105F ambient with soft top, I just notice that over time it gets weaker

I typically do run recirculate normally and I know it's working because I can feel recirculate be a little bit stronger in terms of air flow and maybe quicker cooling

Not sure if the drain is blocked but I do notice a pretty typical puddle after AC use and it doesn't seem like condensation drip just from the pipes alone

Here's a video below in regards to the wiggling I've noticed. Is it s
upport to pivot like that? This was from cold starting in the morning and after idling for about 10 minutes. You can see some condensation build up around the pipes.

 

[Grenadiers]

Spend 65 bucks at Harbor Freight on their R134a gauge set. The gauges on the Freon can are not the greatest. If that joint was leaking, you’d have a noticeable Freon leak. So it’s probably ok.

 

[Mall'er]

Not sure if that much movement is normal, but there should be some. I wouldn't keep poking at it, just to be safe. The ideal test would be to evacuate the system and pull a vacuum to see if you have any leaks, but I suspect that is not the answer you are looking for.

After you run it for a bit with the ac on, you should be able to see the drain dripping. Normally you would get a musty smell in the jeep if it was blocked, but not sure if you would in your heat and a soft top.