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This thread is being created to address the common issues that pop up at this time of year due to people firing up the A/C in their trucks for the summer months. This is an ever changing master list of common A/C problems and their solutions as gathered from this section. If you have a problem that is not addressed in this thread please feel free to either make a new thread about it, or PM either myself (shrpshtr325) or 45Autopete for assistance, and we will make sure that it is added to this thread.
To start, here is some basic information on systems using R134a as the refrigerant (courtesy of 45autopete)
Here are some general guideline for A/C system pressures and temperatures based on ambient outside temperature. Remember that these are a guideline and your actual temperatures and pressures will vary depending on humidity in the air and the condition of your system. When running the car at idle to check the freon level it is a good idea to have a water hose handy and spray water on the a/c condenser. The condenser is located in front of the radiator.
For vehicles currently running with freon R-134a only
Outside-----low side-------High side------Center vent temp
60 F -----28-38 psi----130-190 psi ----44-46 F
70 F ------30-40 psi ---190-220 psi ----44-48 F
80 F ------30-40 psi ---190-220 psi ----43-48 F
90 F ------35-40 psi ---190-225 psi ----44-50 F
100 F -----40-50 psi ---200-250 psi ----52-60 F
110 F -----50-60 psi ---250-300 psi ----68-74 F
120 F -----55-65 psi ---320-350 psi ----70-75 F
You can also use this good rule of thumb with R134a, run fan on High with all windows open and engine at 1500 rpm. High side pressure in PSI should be about 2.2 to 2.5 times outside air temperature in degrees F. Example if it's 90 degrees F, high side should be no higher than 225PSI
Here is a useful trouble shooting chart for systems currently running on freon R-134a
Low Compressor Discharge Pressure
1. Leak in system 2. Defective expansion valve 3. Suction valve closed 4. Freon shortage 5. Plugged receiver drier 6. Compressor suction valve leaking 7. Bad reed valves in compressor
1. Repair leak in system 2. Replace valve 3. Open valve 4. Add freon 5. Replace drier 6. Replace valve 7. Replace reed valves
High Compressor Discharge Pressure
1. Air in system 2. Clogged condenser 3. Discharge valve closed 4. Overcharged system 5. Insufficient condenser air 6. Loose fan belt 7. Condenser not centered on fan or too far from radiator
1. Recharge system 2. Clean condenser 3. Open valve 4. Remove some refrigerant 5. Install large fan 6. Tighten fan belt 7. Center and check distance
Low Suction Pressure
1. Refrigerant shortage 2. Worn compressor piston 3. Compressor head gasket leaking 4. Kinked or flattened hose 5. Compressor suction valve leaking 6. Moisture in system 7. Trash in expansion valve or screen
High Suction Pressure
1. Loose expansion valve 2. Overcharged system 3. Expansion valve stuck open 4. Compressor reed valves 5. Leaking head gasket on compressor
1. Tighten valve 2. Remove some refrigerant 3. Replace expansion valve 4. Replace reed valves 5. Replace head gasket
Compressor Not Working
1. Broken belt 2. Broken clutch wire or no 12v power 3. Broken compressor piston 4. Bad thermostat 5. Bad clutch coil 6. Low Refrigerant - low pressure switch has cut off clutch power
1. Replace belt 2. Repair wire or check for power 3. Replace compressor 4. Replace thermostat 5. Replace clutch coil 6. Add refrigerant
Evaporator Not Cooling
1. Frozen coil, switch set too high 2. Drive belt slipping 3. Hot air leaks into car 4. Plugged receiver drier 5. Capillary tube broken 6. Shortage of refrigerant 7. High head pressure 8. Low suction pressure 9. High suction pressure 10. Defective expansion valve 11. Frozen expansion valve
1. Turn thermostat switch back 2. Tighten belt 3. Check for holes or open vents4. Replace drier 5. Replace expansion valve 6. Add refrigerant 7. See problem #2 8. See problem #3 9. See problem #4 10. Replace expansion valve 11. Evacuate and replace drier
Frozen Evaporator Coil
1. Faulty thermostat 2. Thermostat not set properly 3. Insufficient evaporator air
1. Replace thermostat 2. Set to driving condition 3. Check for excessive duct hose length, kink or bend.
If you can't get your a/c to turn on then use this chart to determine if you are low on freon. Remember that this is a general char and will very for different makes and model cars and refrigeration units
Now for some problems which you our members have come across, and the solutions
Originally Posted by kid289
Due to the weak A/C system in fist gen durangos (i have a 98), can i take the complete A/C system (evap, condensor, compressor, etc.) out of a 2004 or newer durango and put it in my 98? It blows cold, but has always been like this since i bought it in 99. My wife is driving me crazy about the A/C. She wants to sell the truck. Over my dead body!! Thanks
in short, NO the A/C systems from the newer generation (04+) will NOT fit on the older generation, in order to make the early durangos(98-00) A/C blow colder you can add an E-fan(the later run of 1st gens came with an e-fan) to the better cool the A/C condensor and make sure that the system is charged to spec and the compressor is still good. Also make sure that the stock fan clutch is good (spin it by hand with the engine off, if it spins more than 1/2 a turn replace the clutch)
Originally Posted by vox87
My A/C blows cold (very cold), when going down the road, but blows lukewarm when idling at a stop light or just in park idling.
So far, I've done the following:
- Had the freon checked and it was good
- I've swapped the A/C relay with a good relay
- Replaced the two fuses (40 amp HEVAC FAN fuse and 10 amp A/C fuse)
- The electric fan was dead, replaced it
Still not getting cool air when idling.
One thing I've noticed after I turn off the engine, the compressor seems to make a high pitch sound (like pressure being released). Takes about a minute or two before it does and right before it does, the clutch (pulley) moves a bit.
I'm guessing these could be the culprits, but I'm assuming this is not a DIY type fix.
I'm at a lost at this point. I was trying to avoid an AC shop since I don't know a good one and also trying to avoid spending any extra money. I had high hopes the e-fan would have done the trick.
Thanks for any help on this.
If your compressor is making a high pitched sound after turning off the engine, it is the high pressure side bleeding off into the low side. You will need a new compressor, that is why it will not cool at an idle but will cool above idle. Change out the compressor and drier (accumulator).
Originally Posted by jhyneman
Long story short, My A/C hasn't been charged for a while so I bought a used compressor that was "tested" and "good". Installed it, replaced my h-block and vac the system down to 25. I put a little freon in till the switch activated and then put guages on and continued filling the system. I am reading 30 on the low side and 250 on the highside at 95 degrees. The Air is cool but not cold. I think that there is too much of a split but here is the problem. At the current pressures at idle the belt won't quit squeeling going down the road it will stop unless at a stoplight or stop sign. If I try to add any more freon it squeals all the time. I was looking at the compressor pulley and when it starts squealing the compressor slows down and on ocassion will completly stop spinning.
Is my compressor going out? I have a new belt already and it is not a cheap one.
Ok I can't get the proper ammount of freon in without the compressor locking down. As far as the oil. It was serviced and the system has the right ammount of oil, I double checked that when I first started having the problem. I will have to check on the clutch clearance. How do I measure that. I did install a new drier.
Clutches are the number one reason that causes squealing, it is usually just partly engaging. You should have around .025-.030 clutch clearance, between the plate and pulley. It is always better to get a new compressor and air drier to install instead of a used one. Used compressors might show good but a person does not know how many miles were on that particular vehicle that it was taken off of. (DO NOT USE A USED OR RE-MANUFACTURED COMPRESSOR, SPEND THE MONEY AND BUY NEW!!!!!! it will save you headaches, time, effort, and money in the long run)
Also make sure that you put the correct amount of freon in the system(this tag is from a 2002 4.7l with dual a/c, but it lists both system fills, and should be consistent across the model lineup)
Originally Posted by Chuck D
I'm sure it's coming from A/C drain back up but can't find where the drain tube comes out of cab. How do you clean out drain? Thanks Chuck
The drain should come out through the firewall on the passenger side of the truck, you SHOULD be able to clean it out with a piece of wire coat hanger, but alot of people had no clog and the problem was caused by air pushing the water back into the hose as you drive, putting a 90 degree elbow on the end to point it down will solve the problem.
Originally Posted by crazy5269
I just picked up a 98 Durango with the 5.9 and had to replace the A/c compressor but for the life of me i cant find the expansion valves front and rear a/C please help thank you is there a possibility that it has an orifice tube? and not an expansion valve
The answer to the question is that the expansion valve is located on the passenger side by the firewall and you will have to unbolt the lines and then the valve. Make sure you use new gaskets. The rear is located on the evaporator, inside the vehicle, under the trim on the passenger side rear.
More *VERY* detailed information is available in PDF form for
1998-2000 Durangos HERE
These PDFs provide troubleshooting and diagnostic procedures in EXTREME detail and should you attempt to follow the procedures you assume all of the risks associated with the work.
That said, we are working on gathering all the problems into one place at this point so the thread will remain locked until such time as it is completed, and then opened up to the general membership, this is to ease complications in getting all the information presented in a clean, clear, and concise manner.
Thank you for your understanding,
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Last edited by shrpshtr325; 07-03-2010 at 11:34 PM..
I was visiting family in Indiana over the weekend. On the way down(4 hour drive) I had the A/C on low the whole way. Worked flawlessly! As a matter of fact, always has worked flawlessly! I didn't drive it once while there. The Durango sat for 2 1/2 days.
Just realized I posted this in the wrong thread! So sorry!
When I left, I turned the air on hi and noticed that it was not cooling off like it should. The air was cool but not cold. I had to run the front and rear A/C on hi also just to keep almost comfortable. While driving, I periodically reached back to feel the air coming out of the rear vents and it was slightly cooler than the front.
I got home and pulled into the garage and a little while later noticed a huge puddle of water that was coming out of the right rear drain tube. Haven't seen that much before. The front puddle was normal size. Also, on the way home, the A/C was making a noise that I could hear from the inside, but not so much from the outside.
I have a 2003 Durango R/T 5.9. i have joined the fraternity of those that have AC issues, so far I have changed the blower motor the AC resistor under the dash and checked the relay and fuses. After replacing the resistor when i turned on the air it ran for a few seconds and then went completely off, now it seems as there is no pwr getting to either the switch itself or the blower motor but the relays and fuses seem fine what else do i need to do its 90 degrees in michigan and riding with black leather is like being in the preverbal "chariot of fire" and its a red RT too. if anybody has some insight i would appreciate it.. thanks
Last edited by Drew C; 07-14-2010 at 04:17 PM..
Reason: adding information
is the clutch attempting to engage? if so it sounds like you are low on refrigerant, which means you have a leak that you need to find, unfortunately this is a shop only job as the system needs to be vaccumed down to see if it holds a vac (this will tell you if there are leaks, as well as dry the system out) and then recharged to the correct weight for either single or dual air
-Phillip's Law: Four-wheel-drive just means getting stuck in more inaccessible places.
the rear a/c heat has their own heater core/ evap core in the panel on the passenger side behind the plastic panel,
also what year is your truck, it almost sounds like you are on an older model (98-00)with vacuum actuated doors which would make it appear like the air had stopped coming out where you wanted it to, i would check for a bad vacuum line going into the dash.
-Phillip's Law: Four-wheel-drive just means getting stuck in more inaccessible places.
Its a 98, I did find most of what I had asked after more reading. lol. Guess I shouldnt try to read through all these so late at night. Well that and Im so excited about this "new to us" truck. I love this thing. Thank you though. Im sure I'll have questions that havn't been answered at some point.
Edit -- I made my signature right after that last post, Guess this forum doesnt update all of your posts when you add or change sigs.
I have a 2000 Durango with rear AC and 4.7 engine. The AC blows 70 degree air from center dash vent at idle and 60 degree air when driving - outside air 80 degrees. Veh has 100K miles. The following work was done:
Condenser was changed
rear expansion valve was changed (because it was leaking)
system was evacuated down to 28 inches for 1 hour
2 lbs of 134a added to system.
vacuum lines and doors appear to be working ok
fan works on all speeds
heat works ok
controls appear ok.
Front expansion valve was NOT changed.
Filter/dryer/accumulator was NOT changed.
Pressure readings at idle Low side is 47 high side is 170 outside air temp is 80 degrees
Last edited by project_1_man; 08-05-2010 at 11:13 PM..
Reason: additional info
I just create an account to try and diagnose my "Fog Horn" AC. While at highway speed this does not happen. Just after stopping and while stopped, a "Fog Horn" Type noise emits from in dash. I read that the system might be over charged. I just had the AC serviced at a shop in Olympia. I took it to them because it was not making cold air. I also took it to them because they put on a new AC clutch last summer. Any ideas what might create the "Fog Horn" sound??