Couple of Air Conditioning Questions

For the most part my AC works great... 90 RENIX with R-12.

It blows out very cold when you put your hand right next to the vent... but if you put your hand back about 18" from the vent, its not that cold at all. Even with the blower on high. Is this just an inherent problem with having an older vehicle? Is there anything that can be done to improve this? Insulating the ducts for example?

As a comparision... I also own a 2001 Dodge Ram 1500. The Jeep is colder than the Dodge when you put your hand next to the vent (probably an 134a vs 12 thing). But if you put your hand back 18" from the vent its still pretty cold. Now granted the dodge is only a 2 door and has a fairly small area to cool compared to the Jeep... but its almost as if maybe the velocity of the cold air is nowhere near the power of the Dodge. The blower on the Jeep seems to be working great. You can really hear it ramp up when you put it on high and the AC on MAX.

Does anyone have some opinions on the subject?

A couple of other weird things with the Jeeps AC:

1.) If you have the AC blower on High after its been running for awhile the temperature of the air is slightly warmer compared to if you turn down the blower setting a couple notches. Granted, your not getting it blown at you as hard... but it is colder air. Whats up with that?

2.) I know that most AC systems drain condensation after they have been in use. In my Jeep, i never have yet to see a small puddle under the Jeep after using the AC. This doesnt seem normal to me. Should i be investigating something in this area? If so what?

I know there are a few issues here that i have .. but any help / suggestions would be appreciated.

Thanks for your time.

Your AC sounds like it needs a recharge.
1. Air moving slower over a slightly cold heat exchanger will get colder than if it runs over it faster. Only so much heat is being pulled out of less air makes air colder than pulling same amount out of more air.
2. Your heat exchanger probably isn't getting cold enough to remove significant moisture from the air.

Look at the AC pipe on your Ram (under the hood). It probably gets frosty when you run it. The Jeep probably doesn't.

winterbeater said:

Your AC sounds like it needs a recharge.
1. Air moving slower over a slightly cold heat exchanger will get colder than if it runs over it faster. Only so much heat is being pulled out of less air makes air colder than pulling same amount out of more air.
2. Your heat exchanger probably isn't getting cold enough to remove significant moisture from the air.

Look at the AC pipe on your Ram (under the hood). It probably gets frosty when you run it. The Jeep probably doesn't.

Click to expand...

It was just recharged and checked for leaks... should i take it back to the place that did the work and have them look at it again? If so what should i say?

Your right about the RAM.. it does get frosty on the pipes for the ac. They also feel much colder than the Jeeps lines do. The Jeeps lines dont get frosty. Sometimes not even that cold to the touch. Are you saying this is why i dont get that small condensation puddle?

Yes. Take it back and tell them it isn't getting cold. The line has to at least get frosty. That is why you don't get the puddle. It's like when you take a cold beer out on a hot day and it makes a puddle on the table. A warm beer won't do that. You might after you drink the warm beer though. LOL

Out of curiousity i wonder why then when i put my hand next to the vent its outputting super cold air. Colder than the dodge... but not cooling the lines down enough to make them frost....

Sorry, don't know. The real standard to tell when AC is working good is to put a thermometer in the center drivers vent. In recirc mode with engine running 1000RPM, windows open, fan on high, the temperature should read at least 40 deg F below ambient.

They did that test when it was in and recharged tested for leaks etc. 36 degrees (or was it 34 .. cant remember exactly but it was in the thirtys). As i said thats not problem right at the vent... but 18 inches back its just cab air being pushed around (what it feels like anyway).

Im starting to think that the vents and ducting in the 11 year newer dodge are just that much better about moving air around then my almost 20 year old jeep. That and the much smaller cab area being cooled. I guess i was just hoping that there was something i could do about it.

But your pipe isn't frosting up. That is a sure sign it's not up to par.

I think i agree with you there... however.. i also think that im setting myself up for failure and more importantly wasted time. If i just tell them yeah the pipe isnt freezing but its cool inside at the vents.. is that really a problem to them?? Probably not.. im sure there response will be hey its working.. sorry dont know what else to tell you.

Put a thermometer in there yourself with the blower on high. I bet it's not as cold as you think.

Ok ill give that a shot...

Thanks for your time with this.. and sorry if it feels like im not listening or reluctant... i just like to be very sure before i take further steps.


BTW which is recirc mode? Max AC?

I think i fixed the problem .. its been working well ever since.

I read awhile back that the fins on the front of the ac clutch can be tapped in towards the compressor to close a gap that forms there. Either that, or taken apart and have some shims removed. I took a hammer, and gave light taps to these fins to help close the gap.

Once i did this, everything seemed to improve. I even started to get small condensation puddles left over under the Jeep.