Not Another A/C Thread

[User_15115]

Apologies for another A/C thread, and I've seen this question asked a couple times, but haven't seen an answer. However, it's hard to parse through all the long A/C threads. I generally don't have a problem with the A/C performance except for one issue. When the truck starts the A/C blows really cold, regardless of the temp. I have to turn the temp control up really high to try and combat the freezing cold A/C on the mild mornings. About 10 minutes in it seems everything goes back to normal and I have to adjust the temp back down to a normal range. I can almost pin point the exact location on my commute each day where I have to change the temp because heat starts blowing out. It's almost like the inside temp is ignored by the system for the first 10 minutes. Has anyone had and solved this issue?

 

[Jack Whitefield]

You've actually got it backwards. For the first 10 minutes, your AC is working normally. It is cold, as it should be. After 10 minutes, your coolant has reached temperature, and your heater core is bleeding heat into the cab. The reason you have to turn the AC down after 10 minutes, is because your cold AC air is mixing with heated air. This is a known issue with the 2019s. Watch your coolant temperature gauge, and see if it coincides with the AC temperature rise.

 

[c_attle]

I think I understand what he is saying. On cold mornings you want temp to be say 73 or 75 but fan is blowing much colder air at a high rate. My 2010 ram (temp controls set to auto) would lower fan speed until engine temp was warm enough to blow the warmer air. Only then would fan speed ramp up and provide comfortable air temp. It’s like the 2019 doesn’t have that feature.


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[SpeedyV]

I think I understand what he is saying. On cold mornings you want temp to be say 73 or 75 but fan is blowing much colder air at a high rate. My 2010 ram (temp controls set to auto) would lower fan speed until engine temp was warm enough to blow the warmer air. Only then would fan speed ramp up and provide comfortable air temp. It’s like the 2019 doesn’t have that feature.


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This has been discussed in previous threads, of course, but the problem *seems* to be that the temperature sensors don’t read properly for at least a few minutes. The result is that you might get cold air blowing on you in winter or hot air blowing on you in summer - or any combination in between - for several minutes at startup, until the system FINALLY calibrates itself and settles down.

 

[ldoh]

This has been discussed in previous threads, of course, but the problem *seems* to be that the temperature sensors don’t read properly for at least a few minutes. The result is that you might get cold air blowing on you in winter or hot air blowing on you in summer - or any combination in between - for several minutes at startup, until the system FINALLY calibrates itself and settles down.

Interesting. I hadn't heard the cabin temp sensor took time to read correctly. The outside temp sensor isn't accurate but the a/c shouldn't use that to close the cabin temperature feedback loop.

 

[SpeedyV]

Interesting. I hadn't heard the cabin temp sensor took time to read correctly. The outside temp sensor isn't accurate but the a/c shouldn't use that to close the cabin temperature feedback loop.

Yeah, it’s a bigger problem in winter, when the system blows ice-cold air for several minutes.

 

[c_attle]

Yeah, it’s a bigger problem in winter, when the system blows ice-cold air for several minutes.

Interesting and hopefully fixable. Thanks for the clarification.


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