Cooling SystemQuestionCommunity Starter

2013 Infiniti G37 xS — a/C is cold while driving, warm at stoplights

V8MechanicishCommunity StarterMay 27, 20262013 Infiniti G37 xSBoston / New England
A/C gets properly cold on the highway but becomes noticeably warmer at long lights. It cools down again almost immediately once the car is moving. Could this still be a refrigerant issue or does that point more toward airflow/fans? I'm in Boston / New England. I'd rather test this logically than start replacing parts.
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18 replies

ColdStartRunner19Community StarterCommunity StarterMay 27, 2026permalink
This is usually cheaper to test than to guess. Capture voltage while the 2013 Infiniti G37 is actually failing — after it restarts you've lost the clue. If the cheap test changes it, stop and reassess. This is from a 2013 Infiniti G37 in Boston / New England. I'd want that in writing, not as a promise. Make the next action something you can finish this week. Wrote this up on my lunch break.
RotorLearner50Community StarterCommunity StarterMay 28, 2026permalink
Same neighborhood, different next step: Swap the cheap/easy piece first on the 2013 Infiniti G37 and see if the fault moves. If the cheap test changes it, stop and reassess. On “a/c is cold while driving, warm at,” that was the fork that mattered for me. Stop there until you know. I already checked the easy fluid levels.
PixelHauler75Community StarterCommunity StarterMay 27, 2026permalink
Start with the test that can prove you wrong. Move a coil or plug on the 2013 Infiniti G37 if it's cylinder-specific and see whether the code follows. You'll know quickly if you're on the wrong tree. Stop there until you know. Parking it somewhere I can hear it better next time.
BoostedEnthusiastCommunity StarterCommunity StarterMay 28, 2026permalink
That's a good start, but I wouldn't stop there. Loaded-suspension checks on the 2013 Infiniti G37 catch play that a wheels-hanging inspection misses. That's the branch I'd chase this week. Time, temperature, and whether it's in gear are the notes that actually help a shop. I'm in no rush to be a hero on it.
ColdStartRunner19Community StarterCommunity StarterMay 29, 2026permalink
I hear you, though I'd still want a second check. Capture voltage while the 2013 Infiniti G37 is actually failing — after it restarts you've lost the clue. That's the branch I'd chase this week. On “a/c is cold while driving, warm at,” that was the fork that mattered for me. Verbal 'we'll take care of it' is not a plan. This is the version I'd tell a friend.
RotorLearner50Community StarterCommunity StarterMay 27, 2026permalink
This is usually cheaper to test than to guess. Get a real battery/charging test on the 2013 Infiniti G37, not just resting voltage, before blaming a module. If the cheap test changes it, stop and reassess. Do that first. Parking it somewhere I can hear it better next time.
BoostedEnthusiastCommunity StarterCommunity StarterMay 27, 2026permalink
Log the conditions before you spend. Write temp, speed, and in-gear vs coast when the 2013 Infiniti G37 does it — then decide on parts. Don't erase codes until someone who can help has seen them. On “a/c is cold while driving, warm at,” that was the fork that mattered for me. Time, temperature, and whether it's in gear are the notes that actually help a shop. If your situation is the opposite, ignore me. This is me being the wet blanket on purpose.
BoostedEnthusiastCommunity StarterCommunity StarterMay 27, 2026permalink
If it were in my driveway, get a real battery/charging test on the 2013 Infiniti G37, not just resting voltage, before blaming a module. If the cheap test changes it, stop and reassess. Write the result down so the next test isn't a repeat of the last one. I'd sleep better after that step, even if it finds nothing. Only after sitting overnight so far.
PixelHauler75Community StarterCommunity StarterMay 28, 2026permalink
Start with the test that can prove you wrong. Write temp, speed, and in-gear vs coast when the 2013 Infiniti G37 does it — then decide on parts. Save the big job until that test fails. Stop there until you know. Next check is the cheap one I can do in a driveway.
BoostedEnthusiastCommunity StarterCommunity StarterMay 28, 2026permalink
Ask what changed right before it started. Swap the cheap/easy piece first on the 2013 Infiniti G37 and see if the fault moves. Don't erase codes until someone who can help has seen them. Time, temperature, and whether it's in gear are the notes that actually help a shop. Heat soak after errands is the other window.
TruckTech84Community StarterCommunity StarterMay 28, 2026permalink
If it were in my driveway, loaded-suspension checks on the 2013 Infiniti G37 catch play that a wheels-hanging inspection misses. You'll know quickly if you're on the wrong tree. Monthly payment math is how wallets disappear. Only after sitting overnight so far.
TruckTech84Community StarterCommunity StarterMay 28, 2026permalink
Intermittent stuff lies if you only catch it once. Write temp, speed, and in-gear vs coast when the 2013 Infiniti G37 does it — then decide on parts. Don't erase codes until someone who can help has seen them. On “a/c is cold while driving, warm at,” that was the fork that mattered for me. This is from a 2013 Infiniti G37 in Boston / New England. Parts cannon is a personality type I try to avoid. I'm keeping receipts and dates in one folder.
OldSchoolHunterCommunity StarterCommunity StarterMay 28, 2026permalink
Ask what changed right before it started. Two 2013 Infiniti G37s can feel identical and have different causes, so measure before you copy someone else's repair. If the cheap test changes it, stop and reassess. If you share a photo of the worksheet, easier to sanity-check. I already checked the easy fluid levels.
ColdStartRunner19Community StarterCommunity StarterMay 28, 2026permalink
I'd want a measurement, not a hunch. Loaded-suspension checks on the 2013 Infiniti G37 catch play that a wheels-hanging inspection misses. You'll know quickly if you're on the wrong tree. I'd want that in writing, not as a promise. This is the version I'd tell a friend.
ColdStartRunner19Community StarterCommunity StarterMay 28, 2026permalink
This is usually cheaper to test than to guess. If a shop can't duplicate it on the 2013 Infiniti G37, bring a video plus freeze-frame data, not just a story. Save the big job until that test fails. If they can't show the line item, I assume it's hiding. A day of patience here is cheaper than a wrong part. If this is nothing, great. I want that in data.
TruckTech84Community StarterCommunity StarterMay 28, 2026permalink
I wouldn't throw parts yet. Loaded-suspension checks on the 2013 Infiniti G37 catch play that a wheels-hanging inspection misses. That's the branch I'd chase this week. This is from a 2013 Infiniti G37 in Boston / New England. Monthly payment math is how wallets disappear. I've seen both outcomes, which is why I'd test instead of assume. I already checked the easy fluid levels.
PixelHauler75Community StarterCommunity StarterMay 28, 2026permalink
I'd want a measurement, not a hunch. A pressure test beats staring at a dry driveway if the 2013 Infiniti G37 is losing coolant with no puddle. That's the branch I'd chase this week. Do that first. Wrote this up on my lunch break.
BoostedEnthusiastCommunity StarterCommunity StarterMay 29, 2026permalink
I'd want a measurement, not a hunch. If a shop can't duplicate it on the 2013 Infiniti G37, bring a video plus freeze-frame data, not just a story. That's the branch I'd chase this week. Keep sale price, fees, and rate as three different conversations. I'd rather be boring and correct. Only after sitting overnight so far.
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