A/C only works with truck in movement

[mario_rubio]

2018 Ram 2500 6.7L Cummins Turbo Diesel

The problem is that when the truck is not moving (for example, stopped at a traffic light or idling at home), the air conditioning does not work, and many times the compressor releases refrigerant gas, as if due to high temperature or pressure. (I know it is normal for it to release gas due to temperature or excess refrigerant.)

I have already replaced the fan clutch, checked the high and low fan relays, and they are fine. I also checked the harness from the fuse box to the fan, and it is fine. I confirmed that the relays are receiving 12V. I also checked the fuses, and they are all good.

The A/C only works properly when the truck is in motion.

I’ve noticed that the fan is always on, but it does not seem to increase speed even when I turn on the A/C. It seems like the high-speed function of the fan, which should activate under certain conditions, is not engaging. I initially thought it was the fan clutch and replaced it, but that was not the issue.

Does anyone have any advice on what to check or what to do next?

Thank you in advance

[email protected]

 

[mdc1990zr1]

2018 Ram 2500 6.7L Cummins Turbo Diesel

The problem is that when the truck is not moving (for example, stopped at a traffic light or idling at home), the air conditioning does not work, and many times the compressor releases refrigerant gas, as if due to high temperature or pressure. (I know it is normal for it to release gas due to temperature or excess refrigerant.)

I have already replaced the fan clutch, checked the high and low fan relays, and they are fine. I also checked the harness from the fuse box to the fan, and it is fine. I confirmed that the relays are receiving 12V. I also checked the fuses, and they are all good.

The A/C only works properly when the truck is in motion.

I’ve noticed that the fan is always on, but it does not seem to increase speed even when I turn on the A/C. It seems like the high-speed function of the fan, which should activate under certain conditions, is not engaging. I initially thought it was the fan clutch and replaced it, but that was not the issue.

Does anyone have any advice on what to check or what to do next?

Thank you in advance

[email protected]

It’s a sealed system. I’ve never seen a system vent/release gas unless it’s a leak. When the refrigerant becomes low enough, the compressor will not engage in order to not damage itself

 

[mario_rubio]

There is no leak in the line; I made sure the refrigerant levels were correct (because I refilled it). Compressors have a relief valve to release gas mainly for two reasons: when there is too much refrigerant or due to high temperatures. This is a normal safety behavior.

The problem is that the fan does not activate high speed, and I can not figure out why.

 

[Daw14]

Clutch fan and or electric fan under hood not operating properly or maybe not at all.
It cools when moving because it now has air movement

 

[mario_rubio]

Clutch fan and or electric fan under hood not operating properly or maybe not at all.
It cools when moving because it now has air movement

but I already changed the fan clutch

 

[Jeepwalker]

Yeah, check fan/clutch. Maybe the new one you installed is flaky.

I was going to also suggest ...there could be a bunch of crud or obstructions in the condenser coil. The condenser is your heat-rejection source (moving heat from the inside of the cabin to the outside). If you off-road or drive at night a lot, there could be tons of dead bugs, mud, grass pieces, etc clogging the condenser, or even behind it (impeding airflow). I've personally had condenser coils get so full of bugs and debris ..leaves, etc (behind where you can't see), a guy had to unbolt and separate from the radiator enough to get in there with a hose to better clean.

If you have a grill guard, lights, winch etc in front of the radiator, that can impede airflow too.

An ill-fitting fan shroud that is sucking air around the shroud (not through the radiator) ...the wrong water pump or aftermarket (smaller) fan (not sticking in the radiator the right amt) can cause insufficient airflow.

This all assumes your refrigerant pressures are correct and pressure switches work properly. There ought to be a ton of AC service places in the Miami area... I would think.

 

[04fxdwgi]

but I already changed the fan clutch

Did you change the clutch too?
Did you check electric fan operation?

As soon as you turn on AC, does the electric fan run? If not, you have other problems that need fixin' and it wasn't the clutch fan to begin with.