Engine Size: 5.9
Refrigerant Type: 134
Ambient Temp: 85
Pressure Low: ?
Pressure High: ?
Country of Origin: United States
I'm at my wit's end. I know these Durangos have sad air but this is crazy. Here's what's happening. I stuck an A/C thermometer in the vent because my wife says she's hot. I live in northern arizona so it's dry but we been running 80 to 90 during the day. Vent temp was 88. Rear A/C was 80. It had been working fine so I thought service was in order. Took it to the local recommended AC shop. I WATCHED THEM SERVICE THIS PILE. Recovery, evacuate, hold vacuum for 45 minutes, and recharge. I've seen this done many times so I knew what to watch for. They did everything by the book. It took almost three quarters of a pound with the vacuum draw. Then they started the thing and continued the recharge. As the filling progressed the compressor began to cycle for 5 to 7 seconds and then shut off. While it cycled it was pulling in refrigerant nicely. I've watched this many times and as the charge approaches 50% or so the compressor cycles longer and longer until it stays on and everything begins chilling. The guys said that as we approach the three quarter mark of filling we should check the vent temp. A lovely 80. The compressor cycled on and off 5 to 7 seconds at a time until the charge was complete BUT IT NEVER STAYED ON AND NEVER GOT COLD. The shop gauges showed nothing to speak of because the compressor didn't stay on long enough. During 1 cycle they showed 36 on the low and 100 on the high and still moving but then it would cycle off and the gauges would equalize again. On the test drive it went to a sad 75 degrees. It was 80 that day. The shop had a thermometer on the wall in the shade. Everything was rechecked and the second test drive was on the local highway where we got a lovely 70 and the rear got a 68. After some discussion the blend door thing came up. They said that the door which is cable operated on this thing ( it's the temperature knob) sometimes doesn't close off the heater core side so you get heat & AC mixed. So the dash was opened up and the cable was adjusted so it closed the heater side off completely. (You can hear it close solid). We started it and no change. Still a joke. So I took it home and griped all evening. Then I decided to put a manual water valve in the intake heater core hose to make sure I had nothing hot in the dash to affect the AC. When I started it I put my own gauges on the system but i couldn't get any long readings because of the cycle on & off thing. I called the shop in the morning and the guy said I should unhook the high side switch which is right by the high pressure hose fitting and jumper the wires together & see if the compressor stays on longer. I did. Nothing. Still on & off. Then He said do the same to the low side switch. Nothing. Still cycles on and off. In the morning I went out to tinker with it and the compressor won't come on at all now (I'm assuming because the outside temp was only 44) So I parked it in the garage & cranked the heater until it was 85. Started it up and the compressor cycled on for about 7 seconds & that was it. On & off with no cooling. Same as before. So later in the day I took a long (1 hour) trip on the highway and the vent temps started coming down. It took more than 30 minutes on the highway before i got a 65. It finally got down to a real good 52. But as soon as I stopped it goes straight back up. The fan clutch was my next item. Changed that and tested the electric radiator fan as well. All works good. You can hear the roar of the fans while it's idling but I get no AC. The compressor NEVERS STOPS CYCLING. Perhaps I have a bad switch in the system somewhere thats turning the compressor off. Is that what those high side and low side switches do? How do those work?What do you think about all this??? And if one of those switches is bad do I have to recharge all over again? Please help. Thanks
Edited: Tue June 03, 2008 at 10:09 AM by patarusky
Mist the condenser with water from your garden hose. Keep doing this for a few minutes off and on. See if the cycling improves along with vent temperatures.
If the ambient temp was 85F, you should be getting a much higher high side pressure (you indicated 100 psi). Is your system thermostatically controlled? That is, trying to obtain a specific temp inside the car? You might want to check the sensor involved and possibly jumper it to see if that makes a difference.
It could also be that the high pressure cutoff switch is defective. Maybe pull that connector and jumper it momentarily to see if that makes any difference.
OK Here's an update. I misted the condenser while it was running. It made no difference. I went to the dealer and bought both the high pressure switch and the low pressure switch. Neither of them made any difference. The compressor will not stay on beyond 5 to 7 seconds NO MATTER WHAT I HAVE DONE. When the car is ice cold like when I first start it the compressor will stay on for about 60 seconds then it begins the cycle routine endlessly. The gauges showed 35 on the low and 120 on the high at idle. Raised up the engine to 1500 and the low showed 30 and the high showed 135. Then I jumpered the high switch. The compressor DID NOT stay on. Then I jumpered the low switch. The compressor DID NOT stay on.WHAT ELSE CONTROLS THE COMPRESSOR ON THIS DURANGO???????????????????.All the dash controls are manual. I had it recharged again today just in case. The sticker under the hood says 1.75 for single and 2.0 if it has rear air. Could that be wrong??? I need an expert here. Thanks
Edited: Thu June 05, 2008 at 11:12 PM by patarusky
Here's a new thing. Just had friend come over to look at this thing. He had a great idea. He said I should check the voltage line going to the AC clutch. It's a simple 2 wire connector. Started the thing and checked for voltage when the clutch came on. Here are the test results : air temperature-72 drgrees. we jumped the 12 volt from the battery into the AC clutch connector. It came right on AND STAYED ON. Within 60 seconds we had vent temps of 50 degrees! Within 2 minutes vent temp was 38 DEGREES! To say I was shocked is an understatement. Obviously the compressor is good. Presures were 110 high 25 low at 72 degrees outside. Revved the engine to 1500 rpm and low went to 22 and high went to 120. So SOMETHING is cutting off the voltage to the clutch but I have no idea what. This durango does not have climate control buttons like to set the temp. It has a simple hot cold knob.Simple fan speed switch. So there are no fancy AC controls. There is no overhead computer like in some dodges that shows temperature, mileage etc.. I don't know if there is some other sensor or switch in this system but I have no more ideas. At least I know the compressor will do it's job if it's allowed to stay on long enough. Please help me before I pull my hair out!!! Thanks
This is not as simple as you think it may be. Your vehicle uses a HP Switch, L temp Cut out Switch, LP Switch, Power Control Module, Comp Relay all which can control the cycling of the compressor. Normal operating pressures at 80 degrees ambient are 20-30 Low side and 140-185 High side.
My suggestion is to purchase the AllData Subscription for your vehicle. It will have the wiring diagrams you need to trace down any electrical issue you may have.
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