Said It Here

Why does my car take so long to warm up and blow cold air?

An engine that takes 30 minutes to reach operating temperature and drops back down to the cold line at higher speeds fails to build enough heat for the cabin heater to work properly. This leaves drivers shivering and wondering if their vehicle will function safely in freezing temperatures.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

  1. 1
    Replacing the thermostat
  2. 2
    Checking engine temperature with a laser thermometer gun
  3. 3
    Inspecting whether the thermostat was omitted or left stuck open
  4. 4
    Running the heat in traffic

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.

r/MechanicAdvice2 people · September 2026

“Truck now rides the Cold line on the gauge when going above 60kmh or 35mph ish”source ↗

“Is it a concern? How will it perform in negative temperatures?”source ↗

Mission-Parsley-2505 · r/MechanicAdvice · 4 upvotes

“After some driving, I realized the the car was taking a considerable amount of driving time to get the temperature. The gauge stayed at 1/4-1/3 towards the cold side. After 30 min it would be right under the halfway mark. The heater does not get hot either.”source ↗

Aggressive_Will_7703 · r/MechanicAdvice · 2 upvotes

Where this came up

People with this problem also raised