A/C randomly not cooling.

[Kmcghghy]

2015 RAM 3500 SLT reg cab. 6.7
4 x 4. Diesel
Occasionally in 2024 September/October I’d start my truck and the a/c wasn’t cooling. After shutting it off and leaving it a few minutes I’d start the truck and it’d work fine.
My neighbor and RAM said it sounded like the Blend Door.
Feb I used the air for the first time and no air. It would blow and you could hear the compressor.
March 3rd I bought a blend door and replaced the one behind the glove box.
When I checked it, it blew cold for about 10 seconds then went hot and stuck on hot. I removed and checked the white wheel. Looked fine.
The white arm moved up and down depending me selecting the hot or cold button.
I removed the fuse to try to reset. Didn’t work.
3/4 I started it and you could hear it blowing but no air coming out of vents. No cold air either.
Unhooked both batteries and it’s now blowing but the compressor doesn’t sound like it’s kicking in.
Went in the house and went back out to go somewhere and it was back to blowing hot air on floor but set for dash.
I’ve heard blend door then possible cabin filter and now the HVAC control switch/Panel.
UPDATE: I went out this morning and did a hard reset on the uconnect and then did one on the climate control system. It’s fixed all the issues with the vents not working etc. It’s 51 here so I can’t tell if it fixed the a/c. The fan kicked into high gear when I turned it on but I didn’t hear the compressor kick in. I’ll see if it holds the rest of the settings when I leave at 2pm.
I am going to get some Freon as I’ve seen that that could be the issue on the cold air not cooling.
Have patience here as I’m a 66 yo female that’s never done this before. If it wasn’t for my IT background and google I’d be totally clueless.

 

[04fxdwgi]

Blend door creates all kinds of problems when it's bad. Electric engine fan kicking on when AC is on?

 

[Fast69Mopar]

2015 RAM 3500 SLT reg cab. 6.7
4 x 4. Diesel.
Occasionally in 2024 September/October I’d start my truck and the a/c wasn’t cooling. After shutting it off and leaving it a few minutes I’d start the truck and it’d work fine.
My neighbor and RAM said it sounded like the Blend Door.
Feb I used the air for the first time and no air. It would blow and you could hear the compressor.
March 3rd I bought a blend door and replaced the one behind the glove box.
When I checked it, it blew cold for about 10 seconds then went hot and stuck on hot. I removed and checked the white wheel. Looked fine.
The white arm moved up and down depending me selecting the hot or cold button.
I removed the fuse to try to reset. Didn’t work.
Today I started it and you could hear it blowing but no air coming out of vents. No cold air either.
Unhooked both batteries and it’s now blowing but the compressor doesn’t sound like it’s kicking in.
Went in the house and went back out to go somewhere and it was back to blowing hot air on floor but set for dash.
I’ve heard blend door then possible cabin filter and now the HVAC control switch/Panel.

Blend doors control temperature and mode doors control which vents the air comes out of. I would suspect the HVAC control head is the culprit but some easy diagnostics with a scan tool can really help in this situation.

I would perform the actuator calibration with a scan tool to make sure that all of the actuators are still able to move freely in both directions.

With a proper scan tool you can see if their are any HVAC DTC's active or stored as well.

 

[chopperman1]

You mention no condensate. Could be that it's plugged up. A plugged condensate drain can lead to a frozen evap. I'd start with blowing the drain out.

 

[Kmcghghy]

Blend doors control temperature and mode doors control which vents the air comes out of. I would suspect the HVAC control head is the culprit but some easy diagnostics with a scan tool can really help in this situation.

I would perform the actuator calibration with a scan tool to make sure that all of the actuators are still able to move freely in both directions.

With a proper scan tool you can see if their are any HVAC DTC's active or stored as well.

So this morning I did the hard reset on the uconnect system as well as the climate control system and it appears that the screen is now working as the airflow is coming out of the right vents and when I move the controls from hot to cold they are working. It’s 48 degrees here so I can’t tell if the a/c is working now. When I press it, you can hear more air being forced out but the compressor isn’t kicking in. But with the temp here it might not come on, maybe???
Sorry I’m a 66 yo female that’s never done this crap before so I’d be clueless without my IT background and google.

 

[Fast69Mopar]

The compressors will come on in almost every situation even when the outside ambient temperature is low like at 48°. Glad the reset on the UConnect system was able to make the airflow come out of the correct vents.

Whenever I want to test the A/C compressor clutch engagement when it is cold outside I turn the HVAC mode to defrost because that setting will turn the compressor clutch on to remove the humidity from the cab and defrost the windows.

 

[04fxdwgi]

Was just going to suggest trying defrost to see if comp kicks on. If it doesn't, it could be the system is low on charge or a bad low pressure cut out switch. Or a bad clutch.

 

[Fastlane85395]

2015 RAM 3500 SLT reg cab. 6.7
4 x 4. Diesel
Occasionally in 2024 September/October I’d start my truck and the a/c wasn’t cooling. After shutting it off and leaving it a few minutes I’d start the truck and it’d work fine.
My neighbor and RAM said it sounded like the Blend Door.
Feb I used the air for the first time and no air. It would blow and you could hear the compressor.
March 3rd I bought a blend door and replaced the one behind the glove box.
When I checked it, it blew cold for about 10 seconds then went hot and stuck on hot. I removed and checked the white wheel. Looked fine.
The white arm moved up and down depending me selecting the hot or cold button.
I removed the fuse to try to reset. Didn’t work.
3/4 I started it and you could hear it blowing but no air coming out of vents. No cold air either.
Unhooked both batteries and it’s now blowing but the compressor doesn’t sound like it’s kicking in.
Went in the house and went back out to go somewhere and it was back to blowing hot air on floor but set for dash.
I’ve heard blend door then possible cabin filter and now the HVAC control switch/Panel.
UPDATE: I went out this morning and did a hard reset on the uconnect and then did one on the climate control system. It’s fixed all the issues with the vents not working etc. It’s 51 here so I can’t tell if it fixed the a/c. The fan kicked into high gear when I turned it on but I didn’t hear the compressor kick in. I’ll see if it holds the rest of the settings when I leave at 2pm.
I am going to get some Freon as I’ve seen that that could be the issue on the cold air not cooling.
Have patience here as I’m a 66 yo female that’s never done this before. If it wasn’t for my IT background and google I’d be totally clueless.

 

[Fastlane85395]

Ac low on charge not enough pressure for pressure switch to engage compressor.