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1st Gen Durango 1998 - 2003 Durango's

Rear ac blowing hot, front sort of cool.

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Old 08-19-2010, 11:24 PM
Gasnmyveins Gasnmyveins is offline
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Default Rear ac blowing hot, front sort of cool.

There you have it. Anybody know what would cause this? The refrigerant is up to pressure, but I don't know what else to check. The front seems to be a little cooler when I turn off the rear ac. It's a 2001 Durango 5.9 SLT plus.
As always, any help is greatly appreciated. Sweating at stoplights just doesn't cut it for me.
Thanks, Gas.
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2001 5.9 Durango 2wd
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Last edited by Gasnmyveins; 08-19-2010 at 11:26 PM..
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Old 08-20-2010, 08:56 AM
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Do you see a puddle right behind your right rear wheel whenever you have the a/c on? If so, then your rear a/c is getting refrigerant and the evap coil is working. Could be a fan issue. We'll leave it up o the a/c experts that will come online soon to help you.
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Old 08-20-2010, 10:02 AM
Gasnmyveins Gasnmyveins is offline
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I didn't know I should look there, but I will after work. I'm not sure if you're taking about the fan blowing air from the rear vents or possibly another one related to the rear ac that I don't know about. The vents in the rear blow air just fine, it's just that the air they blow is worse than useless.
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Old 08-20-2010, 05:46 PM
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The rear air has a blend air door that has an actuator motor on it. Usually in 80% of the time the rear air not blowing out cold is that the joint that the motor goes into for the blend air door will crack and this will cause it not to work at all. It usually will stay on the heat side and not move the door for the cold side to work. Dual A/C units take 2.44lbs of freon and that is the best way to tell if you have enough in your system. Recover, vacuum, and recharge with the correct amount of freon.
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Old 08-20-2010, 06:06 PM
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Old 08-20-2010, 06:06 PM
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If, you have a roof mounted A/C unit on the rear. Then, you may have to change the expansion valve.

General A/C not getting cool:
1. Expansion valves may be plugged, overtime, they may become oversized and not cool properly. Think of a ball point pin with little tiny holes. That's your expansion valve.
2. The Dryer on a car is suppose to remove moisture in the A/C system. Over time this gets full. Water particles are in your line causing the expansion valve to prematurely freeze. Causing the A/C system not to function properly.

Expansion Valve & Dryer are cheap for the Durangos. I purchase mine from an A/C supplier shop locally here in Phoenix, Az. If, you go to the dealer, they are way more expensive. There were 2 o-rings I had to goto the dealer for because, the o-ring kit wasn't big enough. Expansion Valve around $25, Dryer was around $15, o-ring kit around $5

If, you have a compressor, you can goto harbor freight to get a vaccum pump for $12.99.
http://www.harborfreight.com/air-vac...ors-96677.html

Get you a set of gauges: $29
http://www.harborfreight.com/a-c-man...set-92649.html

Set your compressor to regulate at 90psi for the vaccum portion of the Job.

Once, your system is vaccummed. Charge the low side with the can turned upside down. Since it is liquid.

Your high side pressure should be 2X or 2.5X the outside temp.
Example. If your outside temps are 100deg, your highside pressure should be 200-250psi @ 2000 Engine RPM.
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Old 08-20-2010, 10:56 PM
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Wow, great info. I guess I know what I'm doing tomorrow. I should mention one other thing I noticed after work today. It doesn't seem that there is any difference between MAX ac and the non-recirculating setting in the front ac, and I also noticed that it seems to cool a little better at speed. I don't know if that will influence anyone's thinking, but I thought it would be worth mentioning now that I'm finally free to check my posts. I sure hope it doesn't suddenly get a lot more expensive. Also, I had forgotten (mainly because I just got used to it and it never seemed to matter) that the light on my mirror defroster button blinks continuously. The defroster still works, so I quit thinking about it. Now I'm wondering if it means my HVAC control module could be be involved in this. My front doesn't seem to recirculate and the rear doesn't blow cold air, and the lift always blinks. I wonder if I'll be looking for another control module, and if they are expensive. Well, either way, it looks like I've got the right group of guys to talk me through it.
Thanks for your help, and whatever further help you can provide.
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Old 08-21-2010, 06:08 AM
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When you turn your temp. ****, can you hear the plastic door open & close behind your dash? If, you can't it could be something wrong with you cable or the hinge inside of your HVAC box. My 2000 durango does not have an external valve that will shut off hot coolant from coming in the cab. This is all done inside the HVAC box. Meaning if the doors are bad, you could be getting hot air from the heater core. Thus, your car will not cool.

1st.: You really need to check your high side & low side pressure @ 2000 RPM
2nd: make sure the Efan is kicking on
3rd: chech your plastic HVAC doors by turning your temp **** & listen for movement behind your dash. This is the door that seperates the heater core & the cool side.


Then report back.
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Old 08-21-2010, 08:19 AM
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I went outside to check the blend box door. I moved my temp sliders and the temperature changed using both the driver and passenger sliders. At least I shouldn't have to tear apart the dash. I'll check at harbor freight after they open and see if they have the things I'll need in stock. Fortunately, I have a compressor, so I should be able to do what I need to do. How hard is it to change a dryer or expansion valve?
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Old 08-21-2010, 11:41 AM
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I finally got to check, and I do have a puddle by the back tire.
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Old 08-21-2010, 04:13 PM
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The expasion valve & dryer are easy to change. Just make sure you use all the correct O-Rings. The front expasion valve is located passenger side firewall. It's the big aluminum block that the a/c lines run into. The dryer is located under your air intake box (passenger side near front of the car). Before you disconnect any of your lines, make sure you let the pressure out of the lines.

You also have a rear a/c expasion valve if you have a roof mounted a/c unit. I don't know where that one is located, because I never had to change that out yet.

Also, if your just changing out the dryer & expansion valve. You really don't need to add any PAG oil to your a/c system.

When you vacuum the system out, you'll want to make sure you Get at least -28.9Hg on the gauge. So, hook up both high and low side of the gauge. Make sure your valves are opened on your gauge fittings (you have to turn it clockwise, think of it like airing up your bike tire, as you turn it clockwise, the little pin pushes down the pin at your a/c line fitting). Once you hit -28.9Hg, close off the valves at the gauge.

Hook up your can of 134a turn it upside down, purge the line to get all the air out by taking a screw driver and pushing the little pin in between the 2 big gauges. When freon squits out, you have purged the line.

Oh, almost forgot. Make sure the high side valve is closed at the gauge after the vacuum is complete.
Now open up the low side valve (blue) the vacuum in your a/c line will suck in most of the Freon.
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Old 08-21-2010, 04:16 PM
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If you are still unsure, you can go on youtube, and search for charging a/c. It's pretty easy.
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Old 08-21-2010, 04:29 PM
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Once you have Full vacuum, wait 10 min. Before you charge the system. If your a/c system loses vacuum, it means you have a leak.
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Old 08-21-2010, 04:38 PM
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Oh almost forgot, this would be a good time to change out your valves on both high & low side. I used bike tire air valve removal tool for the high side, and a small needle nose plier on the low side. The high side which is the smaller of the two, you can get anywhere. The larger valve, save some time and just get it at the dealer. These are cheap. Only a couple of bucks each.
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Old 08-21-2010, 11:12 PM
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Ok, I finally got my readings. 81 degrees ambient, 75 degrees in the vent at idle. That was the highest fan setting, but not set to recirculate. (I found out with the thermometer that the ac will recirculate). Static test showed 30 lbs on both sides. With the engine at idle, after running for 10 minutes, I had the low side at 8 lbs and the high side at 47 lbs. Neither was a negative number. At 2000 rpm, I had the low side at negative 4 lbs and the high side at positive 56 lbs.
So, my question is, what the heck does that actually mean? Also, I'm still wondering about the rear ac. It does have the puddle by the rear tire.
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Old 08-21-2010, 11:14 PM
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i would send a pm to 45autopete, he is our local A/C tech, you should also have a puddle near the front tire on the passenger side from the front evap core,

tho it sounds to me like its not building up the correct pressure, either low freon or a bad compressor (dont hold me to it, just my thoughts)
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Old 08-22-2010, 05:16 AM
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If your pressure are that low, your a/c compressor shouldn't even be kicking on. To me, you have a leak somewhere.

Low side should be around 30-40 psi
High side should be around 160-200psi

If your pressure are that low, your a/c compressor shouldn't even be kicking on. To me, you have a leak somewhere.

Low side should be around 30-40 psi
High side should be around 160-200psi (for ambiet temps being 81 deg)

Get a can of 134a with leak detector dye and put it in your system. Let your a/c system run and start checking for leaks with a black light.

Do you have a roof mounted a/c for the rear?

Last edited by shrpshtr325; 08-22-2010 at 07:48 AM.. Reason: double posts
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Old 08-22-2010, 12:36 PM
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I already explained on what to do. It sounds like you are low on freon. Recover,vacuum, and recharge! There is no possible way that your system would even kick the compressor in at those readings that you gave us unless you hot wired in your compressor. Start out with the easiest fix first! Recover, vacuum(make sure it holds a vacuum after 10 minutes),recharge. If you still have a problem after what I said, get back to us and tell us what readings you have on your low side and high side. Take the readings at idle and at 2000rpm's.
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Old 08-22-2010, 01:46 PM
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I don't know why it kicks on, but it does. I haven't altered the wiring or anything. I was reading the black line labeled R134A. Maybe I'm not using the gauges properly. To tell the truth, last night would have made a great Youtube video. Several, in fact.
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Last edited by Gasnmyveins; 08-22-2010 at 01:50 PM..
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Old 08-25-2010, 05:27 PM
Gasnmyveins Gasnmyveins is offline
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Quote:
Originally Posted by 45AutoPete View Post
The rear air has a blend air door that has an actuator motor on it. Usually in 80% of the time the rear air not blowing out cold is that the joint that the motor goes into for the blend air door will crack and this will cause it not to work at all. It usually will stay on the heat side and not move the door for the cold side to work. Dual A/C units take 2.44lbs of freon and that is the best way to tell if you have enough in your system. Recover, vacuum, and recharge with the correct amount of freon.
You got it. As far as the rear ac goes, it's the blend door. I was at the dealership getting intake manifold bolts and went over to talk with one of the mechanics. I already had the panels off, so it was easy for him to look and tell me what I need. Too bad they want about $160 for the 2 pieces. I'm hoping I can cobble it together to block the heat side until I can go to the boneyard for the parts I need. (Please, Brer Bear and Brer Fox, please don't put me in the boneyard. Anything but that............)
I still need to recover, vacuum and recharge. Things have been a bit hectic lately. Hopefully I can do it tonight.
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Last edited by Gasnmyveins; 08-25-2010 at 05:31 PM..
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Old 08-25-2010, 05:27 PM
 
 
 
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