What Are the Reasons for No Hot Air from the AC After the Water Temperature Reaches 90 Degrees?
3 Answers
After the water temperature reaches 90 degrees, the reasons for no hot air from the AC include thermostat issues, water pump circulation problems, and airlocks in the cooling system. Thermostat Issues: Whether the thermostat is stuck open or closed, it can cause heating malfunctions. A thermostat stuck closed will prevent proper coolant circulation, leading to excessively high water temperature. If stuck open, the water temperature gauge will always read below 90 degrees, resulting in slightly warm air at idle but no heat at high speeds. Pay attention to the thermostat's operation. Water Pump Circulation Problems: Poor water pump circulation directly causes high water temperatures. Replacing the water pump will naturally resolve the heating issue. Airlocks in the Cooling System: An airlock in the engine's cooling system disrupts the normal operation of the car's coolant circulation, leading to no hot air. If the heater core's inlet pipe is hot but the outlet pipe is cold, it indicates a blockage in the heater core, which needs replacement.
When the engine temperature reaches 90°C but there's still no hot air from the AC, I must say this is quite a common issue. It could be due to a clogged heater core, preventing proper hot water circulation from the engine, thus no hot air output. Alternatively, insufficient coolant or air trapped in the system reduces heat transfer efficiency. A thermostat stuck in the closed position can also cause localized high temperature without sufficient warm air. I've personally encountered this in my own car - a simple diagnostic method: feel if the inlet hose is hot; if it's hot but the AC vents blow cold air, it's likely a core blockage. A faulty air blend door actuator might also keep it stuck in cold air mode. For prevention, changing antifreeze annually and flushing the system can prevent sediment buildup. Don't delay repairs once detected, especially during winter driving when it affects visibility safety. I recommend professional inspection at authorized shops rather than DIY attempts.
I've just started driving, and it's really frustrating that the air conditioning still blows cold air when the water temperature is at 90 degrees. Is it because the antifreeze is too low or leaking? Or is there something blocking the water flow in the heater? A friend mentioned that the thermostat might be broken, causing incomplete hot water circulation. The temperature knob setting also needs to be checked to ensure it's not set to the lowest cooling mode. Last time I tried to check: first, I looked at the coolant reservoir level, then felt the pipe temperature. If the pipes aren't hot, the problem must be in the heating part. Driving without heating in the car is freezing and poses a big distraction risk. Don't forget to maintain the cooling system during regular maintenance, but if it's an electrical issue like the fan not working, a professional shop is more reliable. In short, deal with it promptly and don't delay.
