2012 Dodge Grand Caravan AC issue driving me nuts.

[tbirdtbird]

Stay with JohnHere, 1.6 doesn't seem like much refrigerant. In fact to me it could be undercharged, I have seen that with low charge

[Tim]

There is no 2012 Caravan.

There is a Grand Caravan, few different models.

GCspec.jpg (80.98 KiB) Viewed 6575 times

[Septaric]

You are correct. It is a Grand Caravan with rear AC. I'm going to check the spec. tag again today about the 134a.

[Septaric]

Even if the charge is low please explain the pressure drop with the compressor running. It's like an expansion valve is opening and closing. The clutch never disengages. The other thing I don't understand is if the charge is low why does the high side keep going up when I add more 134a? I'm definitely not a AC man. Still working on it.

[tbirdtbird]

The system is trying to equilibrate to the design temps/pressures and it can't because in my opinion the charge is low

[Septaric]

The system is trying to equilibrate to the design temps/pressures and it can't because in my opinion the charge is low

OK, but how is it doing this??? What's happing to drop the pressure?

[Septaric]

There is no 2012 Caravan.

There is a Grand Caravan, few different models.

GCspec.jpg

I checked the tag again and these specs are correct. Damn if I know what I was looking at. So my system is low at the moment. But is it ok to keep adding refrigerant? The high side climbs with every little bit I add.

[JohnHere]

Your specs are way off. The tag on the vehicle are something like 1.6 pounds for single, 2.6 for double. That's off memory so it's not exact.

Your memory was pretty close to the actual: 6 cyl. 3.6L eng., without rear A/C -- 29 ounces (1.8 pounds) of R-134a and 4.0 ounces of PAG-46.
Same engine, with rear A/C -- 40.5 ounces (2.5 pounds) of R-134a and 5 ounces of PAG-46, which is what I said earlier and also tracks with what Tim said for the refrigerant amount.

[Septaric]

Ok we've decided the charge is low. Should I add more to it even though the high side is high and the numbers are raising and dropping?

[Septaric]

You're supposed to recover any refrigerant, vacuum and then charge by weight. If you can't do that by yourself, you need to have a pro do that. Blindly adding refrigerant is going to lead you nowhere.

In a perfect world yes. I had an empty system and a vacuum was pulled. I added three and one half 12 ounce cans. I don't have a scale. All is great now. It is like someone here said the pressure going up and down was the fan kicking on and off. Thanks for everyone's input. I'm happy with the results.