2005 Jeep Grand Cherokee AC Problem - JeepForum.com

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post #1 of 17 Old 08-01-2011, 01:29 PM Thread Starter
jcarranco
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2005 Jeep Grand Cherokee AC Problem

Hello, I'm hoping someone can point me in the right direction. I have a 2005 Jeep Grand Cherokee that is having a strange air conditioning problem. In the morning, the ac works great, cools down at idle and while running on the highway. By mid afternoon to the afternoon hours, the ac is not running properly. It will cool down, but not the same as early morning. The air seems damp to me also. At idle, there is about a 10 degree temperature difference than running on the highway. I'm burning up, and here in Texas, its been 100+ everyday. Do compressors starts failing, or do they just work or not work? I had a ac technician check the freon levels, and he did add 1 can. But i haven't noticed any difference before or after adding the freon. Thanks in advance if someone can help me.

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post #2 of 17 Old 08-01-2011, 08:42 PM
Briandl
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Where was the "AC Technician" from? What were the pressures after he added the can? What are your vent temps?

2002 Jeep Grand Cherokee Limited 4.7L H.O. V8
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post #3 of 17 Old 08-02-2011, 11:02 AM Thread Starter
jcarranco
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The technician was a friend of a friend, but he's ASE certified. I honestly didn't ask him for the pressure readings so i do not know. I've got a little taylor thermometer and the vent temps this morning read about 55 degrees sitting idle with the AC on high and recirculate, driving to work it went down to about 48 degrees. The temperature outside was about 80 degrees at 8am. Right now at midday, we are already at 93 degrees and the vent temps at idle are 70 degrees on high and recirculate, and driving on the highway it goes down to 60 degrees.
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post #4 of 17 Old 08-02-2011, 11:48 AM
Briandl
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It sounds like you're about ten degrees off or so, but it's hard to diagnose without having any pressures. Honestly the best way to make sure you've got the right amount in the system isn't by pressures but by properly evacuating the system and recharging it.

2002 Jeep Grand Cherokee Limited 4.7L H.O. V8
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post #5 of 17 Old 08-02-2011, 01:35 PM
Ryan101505
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Check pressures they don't lie should be around 30 on low and 250 to 350 on high depending on system also rule of thumb 20 degree drop from outside temp is working I know it sounds crazy I would not won't it to be 100 outside and 80 temp blowing in my face but I would day it should be a steady 50-55
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post #6 of 17 Old 08-02-2011, 01:45 PM
Briandl
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Let's ignore the guy that said it should be a twenty degree drop and then said it shouldn't be 80 when it's 100.

Pressures certainly can lie, an obstruction can cause abnormally high pressure, but if you didn't know any better you might think you were over charged.

If your ASE certified friend was half good at what he did he put in UV dye, have you been able to check how much its leaking? He did use gauges when he put in the refrigerant right?

2002 Jeep Grand Cherokee Limited 4.7L H.O. V8
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post #7 of 17 Old 08-02-2011, 04:52 PM Thread Starter
jcarranco
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I took it today to a shop and asked to evacuate the system and recharge the system. They checked it out and told me all my pressures and levels are good and there are no leaks, but the technician thinks there is a problem with the expansion valve. In his opinion, this is causing the increased temperatures in the afternoon. They recommended another shop since he had never done this type of replacement on the jeep. I took it to the other shop and they said they wanted to make sure that is the problem with their own diagnostics. If it does turn out to be the expansion valve, it can run me between 200-250 to replace it. What do you guys think, to much or sounds right?

Here is something i just noticed also this afternoon. I sat in the passenger side and the air coming out of the vents was warmer that the drivers side. I don't believe i have a dual zone ac, does the passenger side also have a actuator switch for a blend door? I replaced the actuator switch on the drivers side because it was making a clicking noise when the temp knob was moved from cold to hot. Looking at the service manual, i see there is an actuator that controls the passenger side only if you have a dual zone air conditioner.

Am i chasing the right thing? Blend door problem, or expansion valve?
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post #8 of 17 Old 08-02-2011, 06:37 PM
Briandl
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Conflicting info. If your friend put in 3/4 of a pound of refrigerant than you either have a leak, or its overcharged.

To replace it you have to evacuate and recharge the system, that alone runs around 100-125, so the extra labor to remove the valve, and the cost of the part, that price sounds reasonable.

Only two things typically cause a temperature difference between each side, either a low refrigerant charge, or blend doors, but blend door failures are uncommon on WK's, and you don't have a dual zone system any way.

2002 Jeep Grand Cherokee Limited 4.7L H.O. V8
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post #9 of 17 Old 08-03-2011, 07:36 AM
Ryan101505
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What a ******* you sure sound full of yourself pressures do not lie ******* go get a book and study some a/c scenarios.
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post #10 of 17 Old 08-03-2011, 07:40 AM
Ryan101505
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An ac system running in 110 degree weather will not produce the same duct temp that a ac system is running in 80 degree weather I would get pressure readings at idle and around cruising rpm
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post #11 of 17 Old 08-03-2011, 12:22 PM
Briandl
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This is too funny. Why would I get pressure readings at idle, and why would I get them at cruising RPM?

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post #12 of 17 Old 08-03-2011, 01:09 PM
Ryan101505
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If u know anything at all about ac systems u wouldn't have to ask dumb questions
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post #13 of 17 Old 08-03-2011, 01:29 PM Thread Starter
jcarranco
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Come on guys...

Anyways, turns out that it was the expansion valve causing the problems. The mechanic said he had never seen an expansion valve do what it was doing, apparently the pressures on the high side were over 300 and the low was going down to 8. So he replaced the expansion valve and recharged the system and its blowing out cold now in this 100 degree heat blast. Thanks for the help, hopefully someone in the same boat as me might have somewhere to start in troubleshooting.
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post #14 of 17 Old 08-03-2011, 03:24 PM
Briandl
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Makes perfect sense when you know the pressures The expansion valve controls the flow of refrigerant, if it's clogged up by debris, or otherwise malfunctioning you'll wind up with higher than normal high side pressures and lower than normal low side pressures.

2002 Jeep Grand Cherokee Limited 4.7L H.O. V8
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post #15 of 17 Old 08-03-2011, 03:40 PM
Briandl
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And it's not a dumb question.

If you are trying to determine if the system is running at the right pressures you check it in a very specific way. You run it at 1K RPM's, not at idle, or at "cruising rpm's", whatever that is, otherwise you're pressure readings won't be useful.

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