Only "moderately cooler" air conditioning - JeepForum.com
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post #1 of 20 Old 07-06-2020, 09:36 PM Thread Starter
Xmind
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Only "moderately cooler" air conditioning

So I've never been impressed with my ladies Laredo's HVAC system. Currently the max fan, circulating air, with AC on is only slightly cooler than ambient; definitely not suitable for 90+F (32 C) degree days.

I had to replace the compressor about 3 years ago. It worked okay, but not great even then. The charge is at full pressure and it holds it.

So any tips of what to look at next or how to improve the cooling?

When I replaced the compressor, the instructions did say to replace the dryer.... but I did not due to the extra time involved to replace it. Could this have that much of an adverse affect on cooling performance?

Otherwise maybe I need a new ac radiator(heat exchanger) if to make fins are damaged?

Any insight to get this addressed soon would be greatly appreciated.

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post #2 of 20 Old 07-06-2020, 10:29 PM
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who recharged the system? if you used one of those do it yourself cans, that may be the problem. have a good a/c shop evacuate & refill the system. I had to have mine done twice before it got real cold. now it gets down to 42 deg on a 90 deg day. also, the r12 we used in old cars was much better than todays r134
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post #3 of 20 Old 07-07-2020, 05:08 AM
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not replacing the receiver drier generally voids the warranty on the new compressor. they want you to replace the drier because you can have metal shavings in there from when the old compressor seized that will kill the new one too.

how did you evacuate the system after replacing the compressor 3 years ago? if you did not pull and hold a full vacuum on the system after replacing the compressor, that's the problem
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post #4 of 20 Old 07-07-2020, 09:39 AM Thread Starter
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Ah, good points. I suspect the shop that replaced the compressor didn't vacuum down enough.

I have a vacuum, proper ac gauge/ line kit, and a bottle of good refrigerant, so I'll give that a shot.

Thanks.

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post #5 of 20 Old 07-07-2020, 05:41 PM Thread Starter
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[email protected] That proved to be a waste of 2 hours and $60.

Fully evacuated the system into an empty tank. Vaccummed down to -29"H20, pressure held, continued to vaccume for 40 minutes. Put in two 12 Oz R134a cans. Low side pressure right at 60 PSI and high side around 200-250 (can't remember exactly, but for sure >150 and less than 250). But still the air coming out of the AC vents were only about 10 degrees F cooler than ambient like before.

So no leaks, compressor kicks in and pressures are right, but virtually no cooling. The low and high side pipes were both hot.

AC systems aren't that complex, so maybe I still damaged the compressor even though pressures are good?

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post #6 of 20 Old 07-07-2020, 07:52 PM
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Are the blend doors working correctly.
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post #7 of 20 Old 07-08-2020, 10:47 PM Thread Starter
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Quote:
Originally Posted by 19GCTrailhawk View Post
Are the blend doors working correctly.
I assume you mean the ability to direct air out of the desired vent? If so, then yes, all fan speeds work, the AC kicks in when I hit the AC button, and I can select feet, feet/head, head, front defrost, and the two interior circulating options and the air moves to the correct vents.

Or are you talking about the hot/cold dial? I have kept it on the coldest option and haven't tried playing with that. I will check that though. Even if that wasn't working, shouldn't the low side line under the hood be cool/cold?


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post #8 of 20 Old 07-09-2020, 06:49 AM
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The only things that come to mind are airflow (check the blend door) and the expansion valve. If you have airflow, I'd look into the valve.



Your pressures sound like they are close to what they should be and your charge sounds right also.
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post #9 of 20 Old 07-09-2020, 08:32 AM Thread Starter
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Okay, the expansion valve seems like the next thing to check as the blend door seems to be working as I can go from slightly cool to hot in pretty good increments. I hear the air flow sound change as I move the dial throughout the range.

Driving highway speeds or stationary doesn't change the temperature at all, which rules out the ac radiator/heat exchanger in the grill.

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post #10 of 20 Old 07-09-2020, 09:45 PM Thread Starter
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Well so changed the expansion valve....which I now remember that I replaced that when I had the compressor replaced 3-4 years ago. So recharged the system, but absolutely no change in cooling performance.

There is definitely some cooling effect, because if I turn the AC off, it goes to warm air (damn near 100 F today!). But the air coming out is only about 10-15 degrees F cooler than ambient.

So is it possible the blend door is out of position that the max cold doesn't have it moved to the max position? I'm leaning towards this now since the low side line was actually cool....or at least not hot like the engine this time around.

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post #11 of 20 Old 07-10-2020, 10:29 AM
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Agreed that you need to check the blend door for air flow to be sure that the system is routing the warm cabin or outside air over the AC evaporator coil. If the air is not routed to the evap, the expansion valve most likely limit flow of refrigerant. Effectively, without airflow the coil freezes up. The expansion valve senses temperature differences between the refrigerant pipes that flow through it.



An equivalent of this problem is when you don't change your home AC air filter. All of the airflow is blocked. Your a-coil may freeze and the system doesn't work well. Your blend door is equal to the filter.
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post #12 of 20 Old 07-10-2020, 02:22 PM Thread Starter
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Yeah, looks like I'll have to break into the HVAC system to check the doors.

I did do a "calibration" of the system, but no change in cooling performance for me.

FYI for those that don't know (stolen from the thread below):
1. Put the key to the "On" position with the blower fan off.
2. Press and hold the rear defroster button
3. Turn the blower fan on (low is fine) while still holding the rear defrost button
4. After about 5 seconds the defrost button will start flashing and it'll start the calibration process of automatically switching through all the vent motor settings.
This thread has a lot of information: https://www.jeepforum.com/forum/f67/...epair-1215046/

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post #13 of 20 Old 07-10-2020, 03:52 PM
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Do you have a dual climate control unit? If so, you may have a blend door issue.

I have almost the same issue as you but I have the single climate control, which I've not seen any blend door issues with them. Also, in mine, my drivers side has cold air but the rear and passenger side are warm. I've had it recharged at a shop and they suggested I try the expansion valve next.
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post #14 of 20 Old 07-10-2020, 04:19 PM Thread Starter
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Quote:
Originally Posted by T1m View Post
Do you have a dual climate control unit? If so, you may have a blend door issue.



I have almost the same issue as you but I have the single climate control, which I've not seen any blend door issues with them. Also, in mine, my drivers side has cold air but the rear and passenger side are warm. I've had it recharged at a shop and they suggested I try the expansion valve next.
I have the base Laredo with just a single zone, manual climate control.

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post #15 of 20 Old 07-12-2020, 05:05 PM Thread Starter
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Well, I think I found the problem...er, well, at least one problem: the plastic gear for the air-source flap (Blend doors?/A/C Air Actuator?) was broken.

I took the motor off and the sensor, but everything appeared fine. But putting it back together it seemed weird that the flap didn't catch on to anything attached to the actuator motor. After looking at Chirpz's instructions, indeed the gears were completely broken off. I didn't notice it because it was such a clean break and I didn't find any broken debris inside that area.

So I ordered a new aftermarket part from Amazon for $18 (68072190AA per Chripz's instructions).

That said, I'm fairly skeptical this will fix my problem of very poor cooling as I could manually hold the flap in one direction or the other and it didn't affect the temperature of the air coming out of the vents. But we'll see later this week after I get the part and keep my fingers crossed that this'll some how fix it.


FYI on the link the Chirpz's instructions (post 37 on page 3):
https://www.jeepforum.com/forum/f67/...38/index3.html


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