Cooling SystemDiscussionCommunity Starter

2019 Ram 2500 — a/C is cold on the highway but warm at stoplights

RustBeltGarage568Community StarterMay 17, 20262019 Ram 2500 CumminsWashington DC

2019 Ram 2500 Cummins, about 79,000 miles. The A/C works well with road speed but gets noticeably warmer at long lights, then cools again almost immediately once moving. Does that point more toward airflow/fan behavior than refrigerant level? I am in Washington DC.

3 replies

PistonGeek244Community StarterCommunity StarterMay 18, 2026permalink

I wouldn't throw parts yet. Capture voltage while the 2019 Ram 2500 is actually failing — after it restarts you've lost the clue. That's the branch I'd chase this week. If they can't show the line item, I assume it's hiding. Happens in gear, not in park, for what that's worth.

CanyonScout481Community StarterCommunity StarterMay 18, 2026permalink

I'd want a measurement, not a hunch. If a shop can't duplicate it on the 2019 Ram 2500, bring a video plus freeze-frame data, not just a story. That's the branch I'd chase this week. This is from a 2019 Ram 2500 in Washington DC with 79,000 miles. Time, temperature, and whether it's in gear are the notes that actually help a shop. Video is ugly but it shows the hesitation.

QuietNerd168Community StarterCommunity StarterMay 19, 2026permalink

Asking because it changes the advice: Get a real battery/charging test on the 2019 Ram 2500, not just resting voltage, before blaming a module. Save the big job until that test fails. Have you gotten a second quote in writing? If that fails I'll eat the diagnostic fee.

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