Air Conditioning only works when driving forward?!?

dodge
engines
ram
1500
blower-motors
airconditioning

#1

2005 Dodge Ram 1500 SLT Big Horn, 5.8L V8 Hemi



my air conditioning only works when I’m driving forward, and does not work at all any more when I’m sitting still at an idle. this is a new problem. the A/C has worked like a champ for the past year (since I started using this vehicle). I even refilled it by myself last summer, with no issues until now.



when it is at idle, I hear a clicking coming from the A/C system, and the RPM’s arch a little bit. then it clicks again, and the RPM’s go back down. it does this 2-3 times a minute. also when at idle, the air is VERY HOT, considerably warmer than the outside air.



also, I have a pressure gauge for the A/C system (came with the refill kit last summer) and it says that the system is holding too much pressure. it suggests a possible mechanical problem.



1 - what are the possible problems?

2 - is this a DIY fix?



thank you, everyone!


#2

It could be that the fan isn’t working. Without air flow the condenser can’t do a heck of a lot. It could be a DIY fix if the DIYer knows anything about the system or if the problem is covered in the Haynes book.


#3
There are several possible problems.  The first thing that needs to be checked is the pressure on the charge.  Are the fan(s) running when they should (radiator fan and cabin fan? Did you draw a vacuum on it before filling it?  

 My recommendation is to fine a LOCAL INDEPENDENT A/C or Radiator shop.  Have them check it out. I believe it will be easier and cheaper in the long run.

#4

I filled it from the low pressure side, there was no need to pull a vacuum on it (per recommendation from two experienced mechanics). that’s likely not related, as it was 10 months ago. if I had messed it up, it should have shown symptoms in the 30K miles/4000+ hours I’ve driven it since.


#5

I am going to have to agree with JEM on this one. It’s better to leave this job to the experts. It will save you a lot of money in the long run. Did you vacuum the system when you refilled it last summer? It’s an important step that most DIYers leave out because they don’t have the proper equipment.


#6

First with the ac on and going click get out and watch the a/c pulley. Does the center part spin? If the center part spins and you have no cooling then go to a shop. You should not have needed to put in coolant so you may already have a damaged system. Or you might possibly have a stuck heater door or heater valve, that you can check out yourself.


#7

If the clicking is coming from under the dashboard, the problem may be the temperature blend door. This door directs incoming air through either the AC evaporator or the heater core (or a blend) depending on the desired temperature.

A malfunctioning vacuum-operated blend door will move in one direction when there’s high vacuum (idling) and in the other direction at low vacuum (driving), which would result in exactly the situation you describe.

Is your HVAC system vacuum operated? If so, a vacuum leak, faulty accumulator, or faulty actuator could be the problem.


#8

Sonds like your fan or fans are not working. Check to see if they are drawing air adequately at idle. If you have a shop rag, there should be enough air flow through the radiator and condenser to keep a rag pulled against the front of the condenser.

Warm the engine up, turn on the a/c until it malfunctions, and then spray a garden hose on the condenser with everything running. If A/C operation returns to normal, you’re not dumping enough heat off of the condenser.


#9

Inspect the condenser fan motor. If it is inoperative try to turn the fan by hand (with the ignition off!), the motor may be seized. Next check the fuse in the engine conpartment fuse box. I have seen the fuse blow on these due to a high amperage draw from the condenser fan motor. Replacing the fuse may work for a short time but the motor will have to be replaced.
DYI? When replacing the condenser fan motor the condenser and fan must be removed as a unit then disasembled so the system must be discharged (refrigerant reclaimed).