air conditioner would be cold one day and 75 degrees the next. Took it to my mechanic who is very good. He worked on the airconditioner in my ram truck and it blows 45 degrees. he replaced the condensor, expansion valves and new compressor. it has gotten down to about 55 degrees mainly when Im drivin down the road. when stopped the vent thermometer rises to 68 degrees sometimes. any ideas what can be the problem.

 

I'd imagine its got something to do with the compressor running slower than it would be at 2000 RPM. I don't know much about car HVAC systems though, only commercial and residential.

 

Do you have front and rear AC or just front? You would need to verify the correct amount of refrigerant was added especially if it's the dual front-rear system. The weather has an effect on efficiency and if the refrigerant is just a tad higher than the low amount it will work one day and not the next.

Also, check the digital temp display in the cab. It is fed by the temp sensor between the grill and radiator. when AC is not working verify the temp display value is not some wacky amount.

Only other thing is the pressure sensor switch by the windsield washer resevoir. If you have to much refrigerant or very close to high level of refrigerant, depending on the weather, the pressure sensor may read high and shut the system off.

Idoubt it's the fan behind the condenser but that could cause problems also.

HTH

 

Update and thanks for the responses. It was 91 degrees outside this weekend and the vent temp was around 45-48 degrees while I was moving. If I stopped even at a red light, the vent began to climb. It would go as high as 65-68 degrees. Once I started moving again it immediately started to drop to 45-48 degree vent temp. Any more ideas.

 

The compressor is running slower when you are stopped (idling). 65-68 at idle when it's 91 degrees outside is normal. If the refrigerant level is good and all mechanics are good, then it's good. If it bothers you that much, put it in neutral and raise the RPM's up a bit when you are stopped. Seriously, I do that at long lights.

 

I realize that 68 might seem normal while stopped and idling but I have owned the vehicle for five years and it never did it before until about 2 months ago. I also should have added if you sit in a parking lot it will go up to 75-78. now with a new compressor, condensor and expansion valves, new freon out of a new bottle and the system vaccumed I would think it would not do that. Anyway I talked to my mechanic and he has another idea involving the condenser fan so I taking it back next week to have that checked out. I will update if we figure it out. Thanks for the replies.

 

Bald:
I don't see where you mention the year or model of your vehicle. I assume we are talking about a Durango here.
How many miles on it?

Both our 04 Durango and 05 Grand Caravan needed their A/C recharged recently after we noted a downgrade in performance along with some swishing noises in the system when first turned on. This is the first A/C work for either one in their 10 years of service.

While we are at it, what was the diagnosis that your mechanic used to justify replacing so many parts of the system right off the bat?

Did he find a leak or evidence of compressor destruction that would have contaminated the system?

Don

 

It's an 06 Durango limited. Hemi 5.9. Originally the mechanic thought there was a blockage in the condenser. Also discovered metal shavings in the system so thought the compressor was going bad.

 

I have a 05' Durango, and just over the last days or so I noticed when I initially turned on the vehicle I would hear a clicking sound coming from the heater. The sound goes away after a few seconds,...

 

well just to update this I have been driving it and as long as the temp here in south Alabama is cool (rarely) The a/c works ok. However on these hot days it continues to cool great while driving but the vent temp quickly rises when you stop for a 30 seconds. The mechanic tested everything again and then added a secondary fan to the condenser. It hasn't helped that much. I took it to the dealer and they could not get it to duplicate but that could be because the temp outside has been 70's all week. Dang I am out of ideas here except to wait for very hot days again so I can take it back to the dealer.