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Discussion Starter #1
It's me again with my 08 Grand Laredo, 3.7 engine. Have no AC, occasionally it will blow cool air but not cold. Was going to add freon, but the AC Pro can gauge said that no freon was required.

Any thoughts? I'm trying to limp this thing along for another couple years.
 

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Does the clutch engage on the compressor? When it does, is the small line almost too warm to touch and the large line cool enough to draw condensation?
 

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Yes the compressor does engage. The small line gets really hot, the other gets really cold. Today was the first time in a while that we've felt cold air coming out, after we had scheduled to get the AC looked at ? So I hosed the condenser off, didn't look too dirty actually.
 

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I suggest that you don't have a refrigeration problem, but rather a blend door problem. Other late models have that problem also.
 

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I suggest that you don't have a refrigeration problem, but rather a blend door problem. Other late models have that problem also.
Agreed. This is probably the most likely culprit.

But, also keep in mind that those off the shelf pressure gauges that have "low/good/warning/danger" zones are based on "optimum" temperatures. Basically at higher temps you will need to see higher pressure due to the higher exterior temperatures.

Real AC gauges aren't that expensive anymore and it's helpful for troubleshooting purposes to have low and high side pressures.

Here's a chart for temp vs pressure readings for low side pressures.

 

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Thanks, so what do I next?

I'm finding that about the off the shelf AC units. I really do need get a good set of gauges. If it is the blend door is that where the high/low side pressures come into play?
 

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The blend door is a flapper that opens and closes to mix warm air and cold air. In other words, it is hooked to the temperature selector on the dash. You are going to have to get air flowing across the evaporator coil, aka cold air, before you can get an accurate reading on your gauges anyway. Otherwise you will show higher than normal temps/pressure on the high side and lower than normal on the low side
 

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Hey I had to reply. I have a 2008 Jeep Grand Chrokee 5.7 HEMI. My AC went out just as the heat started ramping up for summer. First it was one side then the other side was cooler. I used a can a Freon and the gauges said full. Did not work and was the same. So I took it to my repair shop and I know the owner and he was very nice and went into detail explaining it to me. The cooler air on one side was a bad sign and to fix a broken actuator or door was around 5 hours of labor because it’s behind the dash. A ton of work to get to them. He also explained those cans of Freon are a joke and not to use them. The Jeep needs Exactly 2.5 lbs of Freon to work properly. When it runs low and you use one of those stupid cans it pumps Freon and air both into it at the same time. So you’re just read pressure on The Gague and have no clue how much Freon is actually in the system. Not just that if you use the ones with sealers you basically ruin your entire system and nobody will service it because they can’t use the machine with the sealer laquering up your system. So they dove into it and it ended up being not enough Freon. They suck it all out with the machine and pump exactly the Freon needed. I paid for the Freon service and I’ve had cold air the rest of he summer. Don’t get too excited it’s the door until you have it serviced and they say it’s that. I thought the same thing. Go to a repair shop have have AC Freon service. It’s not to expensive and it’s the first step in resolving the issue. If it’s not that I can be a bunch of things but I’d start with the AC Freon service.
 

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I had the a/c service fittings replaced on my 92 Cherokee since it originally took real freon. It now accepts the R134 refrigerant, not as good as the ol freon but it blows cold enough on days when its 105 outside to offer relief in central California. Local shop converted fittings and serviced for $100 about 10 or 15 years ago.
 
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